Effects of non-genetic and crossbreeding factors on daily milk yield of Ayrshire × (Sahiwal × Ankole) cows in Mahwa station (Burundi)

The study was carried out at the Mahwa station located in Bututsi natural region in South of Burundi at 1850 m of altitude. The objective of the study was to assess the effects of days in milk, cow's calving age, type of crossbreeding, year and month of lactation, parity on daily milk yield of crossbreds Ayrshire (AY) × Sahiwal (S) × Ankole (A) cows. Milk yields were obtained from 9 cows (S) that have been both milked and suckled during the entire lactation, on 8 cows (M) only milked during the entire lactation and on 150 cows (SM) suckled before and milked after weaning. Data were analyzed using the procedure GLM in SAS for S,M, and SM cows separately. All factors affected significantly daily milk yields (P < 0.001). Least-squares means (LSM) for daily milk yields were highest at the 8th (7.16 ± 0.07 l), 8th (7.63 ± 0.35 l), and 7th (7.34 ± 0.39 l) day in milk for SM, S and M lactations, respectively. The Wood model was able to detect 2 main groups of curve shape: standard for SM and S cows and atypical decreasing for M cows. An important decrease in milk production was observed around the 120th day in SM cows corresponding to the weaning period. Crossbreeding improved milk production and highest yields were observed with 50% to 75% of Ayrshire inheritance (LSM = 5 ± 0.05 to 5.51 ± 0.02 l/day). A significant increase was observed from 1977 to 1992 due to the improvement of genetic and management techniques. During this period, LSM raised from 1.26 ± 0.11 l to 4.74 ± 0.03 l per day for SM cows. Unfortunately, the 1993 civilian war destabilized the managerial techniques and consequently, the milk production decreased in Mahwa station. In all cows, milk production was significantly higher from December to May (LSM = 3.96 ± 0.03 l/day) during the rainy season than in September (LSM = 3.12 ± 0.03 l/day) at the end of the dry season.     

Season and physiological status affects the circadian body temperature rhythm of dairy cows

The circadian body (vaginal) temperature rhythm was measured in 36 dairy cows: Holstein–Friesian (HF, n = 12), Jersey (J, n = 12) and their crossbreed, Holstein–Friesian × Jersey (HF × J, n = 12) at six different periods (5-7 days in duration) during the year that could potentially be a seasonal and physiological stressor. These were a) early winter (late pregnancy), (b) early spring (early lactation), (c) late spring (before mating at mid-lactation), (d) early summer (after mating at mid-lactation), (e) late summer (late lactation, early pregnancy) and, (f) early autumn (drying-off at the end of lactation, mid-pregnancy). Live weight and body condition score was recorded on the first day of each measurement period. Live weight differed (P < 0.001) with breed with HF cows heaviest and J cows lightest (HF: 525 ± 51, HF × J: 456 ± 56, J: 401 ± 30 kg). HF cows tended (P = 0.099) to have a higher body condition than either J or HF × J cows although the overall change in body condition during the experiment was similar (P = 0.961) amongst breeds. The circadian body temperature rhythm differed markedly between each measurement period, being flatter and having a less prominent morning nadir and afternoon peak during early winter compared to spring and summer. The timing of peak body temperature was 4-5 h earlier in early autumn in HF and HF × J cows relative to J cows. There was no breed difference (P ≥ 0.162) in daily mean body temperature except for a tendency (P = 0.075) for mean body temperature to be moderately higher in J cows (38.5 °C) during late summer compared to HF and HF × J cows (38.4 °C), primarily due to an increase (P = 0.001) in daily minimum body temperature (38.0 vs. 37.8 °C). The daily range of oscillation (maximum–minimum) in the body temperature rhythm was highest during late summer, particularly in HF and HF × J cows. Minimum body temperature was also higher (P = 0.033) for J cows than HF and HF × J cows during early autumn (37.9 vs. 37.8 °C). In conclusion, season and physiological status of cattle had a profound effect on the circadian body temperature rhythm but there was little difference between the breeds of dairy cows studied.     

Milking frequency affects the circadian body temperature rhythm in dairy cows

The objective of this study was to investigate milking frequency as a potential stressor in Holstein–Friesian dairy cows managed in a pastoral farming system. The circadian body (vaginal) temperature rhythm was measured in cows milked twice-a-day (2x) or once-a-day (1x) in two experiments. The first experiment was conducted at peak lactation (50 ± 11 days in milk, DIM) and the second in response to a transition from 2x to 1x milking at mid-lactation (153 ± 21 DIM). At peak lactation, body temperature was continuously recorded for seven days in 40 dairy cows, milked either 2x (two groups, n = 10 per group) or 1x (two groups, n = 10 per group) from the time of calving. At mid-lactation, 60 dairy cows were milked either 2x (four groups, n = 5 per group), 1x (four groups, n = 5 per group) or switched from 2x to 1x on the afternoon of 156 DIM (2x:1x, four groups, n = 5 per group). Body temperature was measured in three of the five cows per group (36 cows in total) for 10 days from 153 to 162 DIM. Milk yield and total grazing time (Experiment 2 only) were recorded in all cows. At peak lactation cows milked 2x had a higher (P ≤ 0.051) mean body temperature between 1600 and 0000 h than 1x cows (38.6 vs. 38.4 °C; SED = 0.03 °C). At mid-lactation, mean body temperature was also elevated between 1600 and 2000 h in 2x cows compared to 1x cows (2x: 38.6 °C, 1x:38.4 °C, SED = 0.04 °C; P < 0.001) and tended (P = 0.083) to be higher in 2x cows between 2000 and 0000 h. On the day the milking frequency was switched from 2x to 1x (156 DIM), mean body temperature still tended to be higher (P = 0.087) between 1600 and 2000 h in cows continuing on 2x compared with 2x:1x and 1x cows. Body temperature in 2x:1x cows on 157 DIM was lower than 2x cows and similar to that of 1x cows, but there was no consistent effect of milking frequency on body temperature from 158 to 162 DIM. Cows milked 2x had a higher daily milk yield than 1x cows at peak lactation and at mid-lactation (peak lactation 2x: 28.1 ± 5.1, 1x: 24.5 ± 4.7 kg milk per day). Time spent grazing between 1600 and 2000 h was initially at least 22 min higher (P = 0.031) in 1x cows than in 2x:1x and 2x cows on 153 DIM but there were no differences (P ≥ 0.107) in the remaining days of the trial. Milk yield in 2x:1x cows declined rapidly on 156 DIM to be lower (P < 0.001) than both 2x and 1x cows but from 157 DIM began to follow the same pattern as 1x cows. In conclusion, milking frequency had an effect on the circadian body temperature rhythm, particularly in the late afternoon and evening. There was a decline in body temperature from 1600 h if milking frequency was reduced, but this change was not explained by treatment differences in time spent grazing during the same period. The alterations in the circadian body temperature rhythm with milking frequency were likely due to differences in metabolic activity and internal heat production associated with locomotor activity and relative milk production rather than physiological stress per se.     

Milk production responses to pre- and postcalving dry matter intake in grazing dairy cows

Sixty-eight multiparous grazing dairy cows were randomly allocated to two precalving pasture allowances to achieve differential dry matter intakes (DMI) for 29 ± 7.7 d precalving (Low or High DMI; 4.8 or 11.9 kg DM). At calving, cows within each precalving treatment were randomly allocated to one of two levels of feeding (Low or High DMI; 8.6 or 13.5 kg DM) for 35 d postcalving in a completely randomized design and a 2 × 2 factorial arrangement of treatments. Following treatments all cows grazed together and were fed pasture and pasture silage. Daily milk yields were recorded, and fat, protein and lactose concentrations determined weekly for 15 weeks. Blood was sampled weekly pre- and postcalving and analysed for indicators of energy status, growth hormone (GH) and insulin-like growth factor-1 (IGF-1). Body condition score (BCS) at calving was reduced by precalving restriction (P < 0.001; 2.8 and 3.0 for precalving Low and High treatment groups, respectively). Precalving restriction reduced milk fat production by 8.4% during the first 5 weeks postcalving, but differences were not significant subsequently. Postcalving feed restriction reduced yield of fat corrected milk (FCM), fat and protein by 23, 21 and 28%, respectively, during the first 5 weeks postcalving. Decreased (P < 0.05) yields of FCM, fat and protein (11, 10 and 9%, respectively) were also evident for 10 weeks after the feed restriction finished. There was a tendency (P < 0.1) for a precalving × postcalving DMI interaction in milk protein yield during the first 5 weeks of lactation with no effect of precalving level of feeding in cows that were restricted postcalving. The plasma concentrations of non-esterified fatty acids (NEFA), β-hydroxybutyrate (BOH) and GH were elevated in restricted cows precalving, and IGF-1 concentration was reduced. Plasma NEFA and BOH concentrations were elevated postcalving in restricted cows, but no effect of postcalving DMI on GH or IGF-1 concentration was evident. Results suggest that under grazing systems milk production responses to precalving DMI are small, but energy restrictions in early lactations result in significant carryover effects in milk production.     

Nitrogen efficiency of dairy cows as affected by diet and milk yield

The aim of this study, which was part of the EU-financed project Life Ammonia, was to evaluate the effects of dietary components and milk production on nitrogen efficiency of dairy cows. The study included examining the effects of decreased crude protein (CP) concentration in a grass-clover silage based diet and results of mixing whole-crop barley silage (WCBS) with grass-clover silage in the diet, on feed intake, milk production and nitrogen efficiency. Rations were formulated and milk production data were registered individually each month for 42 cows of the Swedish Red Cattle breed during four indoor periods from 1999 to 2003. The range in nitrogen efficiency by the cows, 11 to 398 days in milk, was 18 to 40%, when fed a diet containing 135 to 184 g CP/kg DM, 44 to 56% of NDF as rumen degradable fibre (RDF) and milking 13 to 57 kg of ECM daily. The average CP concentration of the diet, containing mainly grass-clover silage and concentrate, was decreased from 168 g/kg DM (170 g in early lactation) in the control treatment period to 160 g/kg DM (163 g in early lactation) during the following treatment period. The CP concentration was 170 g/kg DM (171 g in early lactation) during the third treatment period, when the grass-clover silage was fed in a mixture with WCBS. Using the whole data set (n = 284 for primiparous, n = 440 for multiparous cows based on measurements each month) resulted in models, in which total DM intake, ECM yield, dietary CP concentration and RDF were the most important factors affecting nitrogen utilisation of primiparous and multiparous cows. Increases in both average DM intake and milk yield by multiparous cows and no changes in average intake and milk yield by primiparous cows fed the low CP diet or the normal CP diet containing WCBS, compared to cows fed the normal CP diet, resulted in similar nitrogen efficiencies among the treatments. Hence, dietary CP concentrations of 160 to 170 g/kg DM can be used for cows in early lactation in commercial herds to improve nitrogen utilisation without causing a simultaneous decrease in milk yield.     

Early lactation dairy cows: Development of equations to predict intake and milk performance at grazing

The objectives of this study were to examine the effect of parity and days in milk (DIM) on dry matter intake (DMI) and actual milk yield (MY_Act) of grazing spring calving dairy cows in early lactation (< 100 DIM) and to develop equations to predict DMI and milk yield for grass based systems of milk production. A dataset containing 335 observations from 134 Holstein Friesian dairy cows was assembled from two early lactation grazing studies. Observations were available for primiparous (n = 130) and multiparous (n = 205) cows during periods of DMI measurement using the n-alkane technique. Animal performance was divided into two classes of DIM: less than 50 DIM (< 50 DIM) or between 51 and 100 DIM (> 50 DIM). Parity and DIM had a significant effect on grass DMI (GDMI), total DMI (TDMI), MY_Act and milk composition. TDMI increased with parity and DIM and ranged from 13.4 kg/cow per day (primiparous animals, < 50 DIM) to 20.1 kg/cow per day (multiparous animals, > 50 DIM). Actual MY increased with parity and decreased with DIM (range: 24.1 kg/cow per day (primiparous animals, > 50 DIM) to 33.0 kg/cow per day (multiparous animals, < 50 DIM)). Multiparous cows had greater bodyweight (BW) and lower BCS than primiparous cows. In the early lactation period a number of variables had a significant effect on GDMI, TDMI and milk yield. These predictor variables included BW, BCS, potential milk yield (MY_Pot), DIM, daily herbage allowance (DHA; > 4 cm), concentrate level and parity. The equations accounted for 79%, 83% and 86% of the variation in GDMI, TDMI and milk yield, respectively. Actual milk yield was always below the MY_Pot of the cows, the mean difference was 5.8 kg/cow per day. As DHA and concentrate level increased, the difference between MY_Act and MY_Pot reduced. This study supports the concept that immediately post-calving offering a grass based diet with a medium level of concentrate supplementation is sufficient to support high milk production in grazing dairy cows.     

Effect of milking frequency in early lactation on energy metabolism, milk production and reproductive performance of dairy cows

The objective of this study was to evaluate the effect of imposing different milking frequencies for the first 4 weeks of lactation on energy balance, blood metabolic profiles and reproductive performance. The milking frequencies imposed were once daily for the first 4 weeks of lactation and twice daily subsequently (X1), twice daily for the entire lactation (X2) and three times daily for the first 4 weeks of lactation and twice daily subsequently (X3). Two weeks prior to the first expected calving date, sixty-three multiparous, Holstein-Friesian cows, were allocated to treatments based on expected calving date, parity (lactation number = 2 and lactation number > 2), BCS and BW. Mean DMI was lower (P < 0.05) on X1 than X2 (15.7 and 17.1 kg/day) over the first 4 weeks of lactation, but DMI on X3 was not different to either. Milk yield was lower (P < 0.05) on X1 than on X2 and X3 (24.1, 31.9 and 31.4 kg/day) from weeks 1 to 4 and at week 10 of lactation (30.9, 33.9 and 33.7 kg/day) but was not different at week 20. Yield of milk constituents followed the same pattern as milk yield. Milking frequency had no significant effect on milk fat or protein concentration but milk lactose concentration was higher (P < 0.05) on X1 than on X2. Cows on X1 experienced less (P < 0.05) negative energy balance than those on X2 and X3 from weeks 1 to 4, with no difference between X2 and X3. Cows on X1 lost less BW (P < 0.05) from weeks 1 to 4 and lost less BCS up to day 73 of lactation than cows on X2 and X3. Plasma NEFA and BHB concentrations tended to be lower and plasma glucose tended to be higher on X1 than on X2 and X3 from weeks 1 to 4, while plasma insulin was higher on X1 than on X2 and X3 for the first 2 weeks of lactation. There was no difference between treatments in any reproductive performance variable measured. These results indicate that reduced milking frequency decreases milk yield and improves energy balance and metabolic status in early lactation.     

Colostrum production by primiparous and multiparous Holstein dairy cows and its usefulness as an estimator of full lactation milk yield

This study determined colostrum production of lactating primiparous and multiparous Holstein dairy cows, as well as the predictability of full lactation milk yield based upon this colostrum production. Holstein cows that calved between December 18, 2006 and December 24, 2007 (n = 134) had their first two post-partum milkings weighed and assayed for density. Cows then entered normal production groups and were assessed for milk yield and milk components every 4 or 5 weeks for the duration of their lactation. Primiparous cows produced less colostrum (10.6 versus 13.6 kg; P = 0.02) and density adjusted (DA) colostrum (5.2 versus 8.5 kg; P < 0.01), but there were no differences in estimated 305 day mature equivalent (305ME) milk production (mean = 13,654 kg) or lactation lengths (mean = 301 days) between parities. Colostrum and DA colostrum were poor estimators of subsequent 305ME milk production within primiparous cows (r² = 0.20 and 0.01 respectively) and multiparous cows (r² = 0.18 and 0.12 respectively). Colostrum production of these high producing cows was somewhat lower than expected, highly variable among cows within parity, higher for multiparous versus primiparous cows, and was not a good estimator of subsequent 305ME milk production.     

The effect of cutting time of grass silage in primary growth and regrowth and the interactions between silage quality and concentrate level on milk production of dairy cows

Two silages were prepared from the primary growth (PG) of timothy-meadow fescue sward at early (E) and late (L) stage of growth. The subsequent regrowth (RG) areas were further harvested at early (EE and LE) and late (EL and LL) stages of growth resulting in six silages in total. The silages were fed ad libitum to 24 lactating Finnish Ayrshire cows and supplemented with 8 or 12 kg concentrate per day in a cyclic change-over experiment with four 21-day periods and 6 × 2 factorial arrangement of treatments. The quality of silages varied markedly within and between the harvests although variation was greater within PG than RG. Postponing the harvest in PG decreased silage dry matter (DM) intake by 0.48 kg and energy corrected milk yield (ECM) by 0.61 per 10 g decrease in silage D-value (concentration of digestible organic matter in DM), while responses and the range between the diets were clearly smaller when RG silages were fed. On average, ECM yield was higher when PG rather than RG silages were fed. The mean response to increased concentrate DM intake was 0.62 kg ECM using diets based on PG. The response increased with increasing growth stage of grass being 0.34 and 1.01 kg ECM / kg additional concentrate DM for E and L, respectively. The difference was mainly mediated by the differences in substitution rates (reduction in silage DM intake per increase in concentrate DM intake, kg/kg), which were 0.71 and 0.22 for E and L, respectively. The ECM response to increased concentrate allowance was on average greater when RG rather than PG silages (0.92 vs. 0.62 kg/kg concentrate) were fed. Milk production of dairy cows reflected the intake of metabolizable energy and no differences in the utilization of it were found between diets based on silages harvested from PG and RG. However, intake of RG silages was slightly lower than that of comparable PG silage, but definite reasons for that could not be identified.     

Effects of body condition score at calving and feeding various types of concentrate supplements to grazing dairy cows on early lactation performance

The objective of the experiment reported here was to establish the effect of canola meal supplements of different protein degradability on the performance of grazing dairy cows with different body condition scores (BCS) in early lactation, and to compare this with feeding a cereal grain supplement instead. The experiment included a total of 72 cows in six treatments in a 2 ^* 3 factorial design, incorporating two BCS at calving (4.1 and 5.6 units on an 8-point scale), and three early lactation pelleted supplements. The three pelleted supplements were 100% wheat (wheat supplement), 50% wheat and 50% untreated mechanically extracted canola meal (a rumen degradable protein supplement), and 50% wheat and 50% canola meal that had been subjected to additional heat and pressure (a rumen undegradable protein supplement). It was hypothesised that fat cows would perform best with the treated canola meal supplement, which provided most rumen undegradable protein, whereas the type of protein would not be important for thin cows, and neither would the type of supplemental energy. Cows grazed pasture after calving at a daily pasture allowance of 35–40 kg DM/cow and were offered 6 kg concentrates each day. Cows were fed these diets for 92 days on average, from calving until three weeks into the mating period. Both canola meal-based supplements resulted in higher (P < 0.05) daily milk production than the wheat supplement (33.3 and 34.0 v. 30.5 kg/cow) in both thin and fat cows. Body condition score at calving positively (P < 0.05) affected average milk yield (31.6 v. 33.7 kg/cow), however, there was a time × BCS × supplement interaction whereby the fatter cows benefited from the use of either of the canola meal supplements for a longer period than did the thin cows. Average milk fat concentrations were greater (P < 0.05) where the canola meal supplements were fed (39.3 and 39.6 v. 35.6 g/kg), and in fat cows relative to thin cows (40.0 v. 36.3 g/kg). Serum urea concentrations were significantly (P < 0.05) lower in cows fed wheat than in those fed either of the canola meal supplements (3.1 v. 4.3 and 4.2 mmol/L). Serum β-hydroxybutyrate concentrations were lowest (P < 0.05) where wheat pellets were fed, and highest (P < 0.05) where treated canola meal pellets were fed, and plasma glucose concentrations were highest with wheat and lowest with the treated canola meal pellets. Thus, the hypothesis was not supported by the results of this experiment.     

Effects of inclusion of whole-crop pea silages differing in their tannin content on the performance of dairy cows fed high or low protein concentrates

The effect of including high or low tannin forage peas as an alternative to soyabean meal on performance and N efficiency was investigated using 18 dairy cows in two Latin square design studies. Two varieties of forage pea; Racer (coloured flowers; high tannin) and Croma (white flowers; low tannin), were ensiled 12 weeks post sowing. The in situ degradability characteristics of the pea silages were determined using 4 cannulated sheep. The low tannin forage had a higher soluble N (a) fraction and a greater extent of degradation (a + b), resulting in a greater amount of N being predicted to be released in the rumen than the high tannin forage. In experiment 1, cows were fed one of three treatments in each of 3 periods of 28 d duration in a Latin square design; grass silage/whole-crop wheat (0.50:0.50, DM basis) and 8 kg/d of a high protein concentrate (GWH); grass silage/whole-crop wheat/high tannin forage pea silage (0.25:0.25:0.50 respectively, DM basis) and 8 kg/d of a high protein concentrate (HTH) or 8 kg/d of a low protein supplement (HTL). The inclusion of forage peas increased (P < 0.05) DM intake by 1.2 kg DM/d, but there was no effect of dietary treatment on milk yield (average of 23.0 kg/d), composition or live weight change. The efficiency of use of dietary N (N output in milk/N intake) was highest (P < 0.001) in cows when fed GWH (0.289) and lowest in HTH (0.234). In experiment 2, cows were fed one of three treatments in each of 3 periods of 28 d duration in a Latin square design; grass silage/whole-crop wheat (0.50:0.50, DM basis) and 8 kg/d of a high protein concentrate (GWH); grass silage/whole-crop wheat/low tannin forage pea silage (0.25:0.25:0.5 respectively, DM basis) and 8 kg/d of a high protein concentrate (LTH) or 8 kg/d of a low protein concentrate (LTL). Compared with GWH, the inclusion of forage peas increased (P < 0.05) DM intake by 2.0 kg/d, but there was no effect of dietary treatment on milk yield (average of 24.5 kg/d). Milk fat content was highest (P < 0.05) in cows when fed LTL (45.7 g/kg) and lowest in LTH (41.9 g/kg), but there was no effect (P > 0.05) of treatment on daily fat yield or any other milk component. The efficiency of dietary N use was highest (P < 0.001) in cows when fed GWH (0.300) and lowest in LTH (0.234). It is concluded that either high or low tannin forage pea silages can replace approximately 1.1 kg/d of soyabean meal in the diet of mid-late lactation dairy cows without affecting animal performance, but N efficiency for milk production is decreased.     

Effect of herbage allowance and concentrate supplementation on dry matter intake, milk production and energy balance of early lactating dairy cows

The objective of this study was to investigate the effect of daily herbage allowance and concentrate supplementation level offered at approximately 40 and 80 days in milk (DIM) and the carryover effects at 120 DIM on the production performance of spring calving dairy cows. Sixty-six (30 primiparous and 36 multiparous) Holstein–Friesian dairy cows (mean calving date — 7 Feb ± 9.9 days) were randomly assigned to a 6 treatment (n = 11) grazing study. The experiment was a randomised block design with a 3 × 2 factorial arrangement of treatments (3 daily herbage allowances (DHA's; approximately 13, 16 and 19 kg DM/cow/day; > 4 cm) and 2 concentrate allowances (0 and 4 kg DM/day). Treatments were imposed from 21 February to 8 May. Following this period (subsequent 4-weeks) animals were offered a daily herbage allowance of 20 kg DM/cow/day and no concentrate. Milk production, total dry matter intake (TDMI), energy balance (EB) and blood metabolites were measured on three occasions — at approximately 40, 80 and 120 days in milk, R1, R2 and the carryover period, respectively. Cows offered a low DHA had a lower post-grazing sward height but increased sward utilisation (> 4 cm) during R1 and R2, there was no difference during the carryover period. Concentrate supplementation increased post-grazing sward height by 11% during R2 but had no effect during R1 and the carryover period. Daily herbage allowance had no effect on milk yield or composition during R1 however a low DHA tended to reduce milk yield in R2. Concentrate supplementation increased milk and solids corrected milk (SCM) yield by 4.1 and 2.8 kg/cow/day, respectively during R1 and also increased R2 milk production performance, this effect extended into the carryover period. Offering a low DHA restricted grass dry matter intake (DMI) during R1 and R2 yet concentrate supplementation significantly increased total DMI (2.3 (R1) and 3.0 (R2) kg DM/cow). Animals offered a low DHA had a significantly lower bodyweight (BW) than those offered a medium or high DHA during P1 and P2. Concentrate supplementation increased BW during P1 and P2 (+ 9 and + 14 kg/cow, respectively). There was no effect of treatment on BW during P3. There was no effect of DHA on EB in R1; during R2 animals offered a low DHA had the lowest EB. Concentrate significantly increased EB in R1 and R2 and increased plasma glucose concentration while it decreased plasma NEFA and BHB concentrations. The results of this study indicate that animals should be offered a low DHA up to 80 DIM after which DHA should be increased however animals should also be supplemented with concentrate during the early post-partum period.     

Effect of virginiamycin and monensin supplementation on performance of multiparous Holstein cows

This study was conducted to determine the effects of monensin or virginiamycin, or both on the performance of and some energy balance parameters in Holstein cows. Forty multiparous Holstein cows were used in a randomized complete block design experiment. The basal diet was a total mixed ration based on lucerne hay (38% of DM) and ground maize (34% of DM). The experimental treatments were (1) control diet (C); (2) control diet plus 15 ppm of monensin (M); (3) control diet plus 20 ppm of virginiamycin (V), and control plus M (15 ppm) plus V (20 ppm). Cows received 8 kg/d (as fed) of the experimental diets plus ad libitum Eragrostis curvula hay from 3 weeks prepartum and only the experimental diets from calving until 60 days postpartum. Cows were milked twice daily. Dry matter intake did not differ between treatments, but energy corrected milk production was increased (P < 0.10) by supplementing V + M (43.3 kg/d) when compared to treatments M (36.9 kg/d) and V (37.9 kg/d). Change in body weight tended (P = 0.11) to be lower for cows supplemented with V + M (− 8.1 kg/60 d) when compared to cows receiving the control diet (− 34.2 kg/60 d). Both treatments M and V respectively, decreased blood BHBA and treatment M increased blood glucose when compared to the control diet (P < 0.10). Results suggest a complimentary effect between the two additives monensin and virginiamycin when supplemented to early lactation cows.     

Relationship between feeding behaviour and feed intake of dairy cows depending on their parity and milk yield

To investigate the relationship between the parameters of feeding behaviour and feed intake, 70 lactating dairy cows (23 primiparous and 47 multiparous) were monitored from the 2nd to 15th week of lactation. Data were collected by using an automatic feeder and electronic identification of individual cows from 10 July 2005 to 16 January 2006. The resulting data of the cows in primiparous and multiparous condition were categorised into groups based on the mean of their milk yield over the first 15 weeks of lactation: primiparous cows with below-average milk yield (LP) and above-average milk yield (HP) with an average of 28.44 and 34.31 kg energy-corrected milk (ECM) per day, respectively, and multiparous cows with below-average milk yield (LM) and above-average milk yield (HM) with an average of 38.70 and 44.49 kg ECM per day, respectively. The parameters of feeding behaviour were calculated based on the estimated meal criterion from pooled data. Parity, level of milk yield, and day had significant effects on some of characteristics of feeding behaviour and feed intake parameters. There was no significant difference in meal duration either between primiparous and multiparous cows or between LP and HP. However, a significant difference between LM and HM was observed. Cows in HM had shorter feeding times but a larger meal size, higher DMI, and feeding rate. Moreover, these cows displayed a stronger correlation between meal duration, daily mealtime and daily feed intake (r = 0.37 and 0.50, P < 0.001, respectively) than any other cow or group of cows of the study. Meal duration, daily mealtime, meal size and daily DMI increased on average about 32%, 20%, 35%, and 22% respectively, considering all milk yield groups from the 2nd to 15th week of lactation.     

Post-grazing sward height imposed during the first 10 weeks of lactation: Influence on early and total lactation dairy cow production,and spring and annual sward characteristics

Increasing the proportion of grazed grass in the diet of the dairy cow is the main target of grass-based milk production systems. Imposing a severe post-grazing sward height (PGSH) in early lactation is one strategy to increase grass utilisation. A grazing experiment was undertaken to investigate the direct and carryover effects of PGSH imposed in early lactation on sward and dairy cow lactation performance. Ninety Holstein–Friesian dairy cows (mean calving date: February 13) were randomly assigned to one of three target PGSH treatments: 2.7 cm (severe; S), 3.5 cm (low; L) and 4.2 cm (moderate; M) from February 14 to April 24, 2011 (period 1; P1). This was followed by a carryover period (period 2; P2) during which cows were randomly re-assigned within their P1 treatment across two PGSH treatments: 3.5 or 4.5 cm until November 13. Sward utilisation (>2.7 cm) during P1 was significantly improved by decreasing PGSH from M (0.74) to L (0.82) and further to S (0.94). At the end of the entire grazing season, the M treatment swards had produced +1.4 t dry matter (DM)/ha than the S and L treatment swards which had similar total DM yields (14.1 t DM/ha). Treatment had no immediate or carryover effect on the proportions of leaf, stem and senescent material in the sward or the quality of herbage selected by the animals. During P1 the cows in S had greater bodyweight loss (−18 kg), reduced milk (−2.1 kg/day) and milk solids yields (−0.21 kg/day) as well as lower grass DM intake (−1.7 kg DM/day) compared with the cows in L and M, which performed similarly (−5 kg, 24.1 kg/day, 1.94 kg/day, and 13.0 kg DM/day, respectively). There was no carryover effect of early lactation PGSH on milk and milk solids yields, fat and protein concentrations during P2. This indicates that cows restricted in P1 were able to adjust production in accordance with the higher PGSH imposed during the remainder of the lactation. The S treatment had numerically lower, though not significantly lower, total lactation milk and milk solids yields, reflecting their significantly reduced yields in early lactation. It was concluded that grazing to 2.7 cm in early lactation is too restrictive for dairy cows. Cows in L and M had very similar total cumulative production performance. As a result, grazing to 3.5 cm during the first 10 weeks of lactation contributes to achieving both high milk output from pasture and high grass utilisation.     

Fit of Wood's function to daily milk records and estimation of environmental and additive and non-additive genetic effects on lactation curve and lactation parameters of crossbred dual purpose cattle

The objectives of this study were to estimate the environmental and additive and non-additive genetic effects on lactation curve and lactation parameters of crosses of Holstein (H), Brahman (B) and Brown Swiss (BS) in Olancho region in Honduras. The data consisted of 54,517 milk yield records from 192 dual-purpose crossbred cows lactating from 2000 to 2005 at the Universidad Nacional de Agricultura de Honduras (UNA). The lactation curve and lactation parameters of interest were the scaling factor to represent yield at the beginning of lactation (a), the factor associated with the inclining (b) and declining (c) slopes of the lactation curves, and the milk yield at initial day of lactation (MY₂₀), peak milk yield (MY_max), day at peak milk yield (t_max), and the total milk yield (TM) per lactation, respectively. The incomplete gamma function (Wood function) was used to estimate lactation curve and lactation parameters from daily milk records of H × B, H × BS and BS × B crossbred cows. The environmental, additive and non-additive genetic effects on lactation curve and lactation parameters were estimated using Dickerson and Kinghorn models. The coefficients of determination of fitness of Wood's function (R²) ranged from 80% to 97% with an average of 93%. The lactation curve of the crossbred cows was similar to those reported for dairy cows grazing in the tropics. Lactation parameters such as MY_max, t_max and TM were significantly (P < 0.05) influenced by environmental sources of variation suggesting the necessity of differential management strategies. The moderate to large positive phenotypic correlation of MY_max and TM indicate that one of the milk yield parameters could be used as a selection criterion to improve either one or both traits. Despite the fact that both genetic models showed similar patterns, the absolute value of the parameters varied. For both models, individual additive genetic breed effect for H breed were significant (P < 0.05) and contributed more to TM than the BS breed. In the Dickerson model, highly positive significant (P < 0.01) effect on TM for H×BS and BS×B crosses was found. The Kinghorn model did not show significant effects of dominance on this parameter. The estimate of recombination effect for all crosses involving B breed were negative and significant (P < 0.05) for positive correlated lactation curve parameters. Although the inclusion of non-additive effects on crossbreeding genetic effects were not all significant for lactation curve and lactation parameters, non-additive effects should be taken into account to improve the Honduran dairy cattle production management.     

Allocation of feed based on individual dairy cow live weight changes: II: Effect on milk production

Based on individual cow live weight gain, feeding strategies were designed for individual feeding of dairy cows in loose-housing systems, and examined in a four-year production trial including 115 Danish Red (DR), 91 Danish Holstein (DH), and 93 Danish Jersey (DJ). The objective of the present paper was to examine the milk yield obtained in response to three feeding strategies. The interrelationship between feed intake and live weight changes is presented in a companion paper.Cows were stalled in a loose-housing system based on automatic milking, automatic recording of feed intake and automatic weighing of the cows. All cows had 3 kg of individually separately offered concentrate (ISC) in addition to a mixed ration (MR). Cows were either allowed a medium energy MR during whole lactation (strategy MR1) or a high energy MR during early lactation, which was reduced to a low energy MR either early or late (strategy MR2-E and MR2-L). The early and late changes were defined as a live weight gain after live weight minimum at 15 and 35 kg, respectively, for DR/DH and 11 and 25 kg, respectively, for DJ. When MR energy concentration was changed, cows on the MR2 strategies were offered 3 kg per day of extra concentrate. The total allowance of 6 kg ISC was stepwise reduced to 3 kg per day as live weight continued to increase until 50 and 35 kg for DR/DH and DJ, respectively.Compared to feeding the MR1 strategy, the analysis showed that feeding the MR2 strategies did not significantly affect milk yield within primiparous DR and DH or within any DJ, as total lactation feed energy intake within these groups of cows was not significantly affected by the feeding strategy. Results obtained for multiparous DH showed that it is possible to increase milk yield without reducing the milk:feed ratio, when MR2 strategies were applied compared to the MR1 strategy. Feeding high energy rations during early lactation caused a higher peak feed energy intake within multiparous cows of DH and DR, but only multiparous DH obtained higher peak ECM yield in response to higher feed energy intake in early lactation. Across breed the results suggested that cows offered the MR2-E strategy might obtain higher lactation ECM yield compared to cows offered the MR2-L strategy due to a higher ECM yield persistency obtained by cows offered the MR2-E strategy. Results on feed intake and live weight changes presented in a companion paper indicated, that cows offered the MR2 strategies obtained a lower extent of mobilization compared to cows offered the MR1 strategy, and feeding the MR2-E strategy significantly increased duration of the mobilization period, which might have increased MR2-E cows' ability to maintain a high milk production during mid lactation.     

Effects of treating rice straw with urea or urea and calcium hydroxide upon intake, digestibility, rumen fermentation and milk yield of dairy cows

Three, multiparous Holstein crossbred dairy cows with initial body weight of 385 ± 19 kg were randomly allocated to 3 treatments of rice straw (T1 = untreated rice straw; T2 = 5.5% urea-treated rice straw (5 g urea in 100 ml water to 100 g air-dry (91% DM) straw); T3 = 2.2% urea + 2.2% calcium hydroxide treated rice straw (2.0 g urea and 2.0 g Ca(OH)₂ in 100 ml to 100 g air-dry (91% DM) straw) according to a 3 × 3 Latin square design. Each period lasted for 21 days in which feed, feces and rumen fluid were collected during the last 7 days for chemical analyses. The findings revealed significant improvements in dry matter intake and digestibility by using 5.5% urea-treated rice straw and 2.2% urea + 2.2% calcium hydroxide treated rice straw. Ruminal pH and NH₃-N were found higher (P < 0.05) as compared with urea-treated rice straw fed group, while blood urea nitrogen and milk urea nitrogen were in normal ranges. Volatile fatty acid concentrations especially those of acetic acid were decreased (P < 0.05) and those of propionic acid were increased (P < 0.05), thus acetic acid:propionic acid was subsequently lowered (P < 0.05) in cows fed with 5.5% urea-treated rice straw and 2.2% urea + 2.2% calcium hydroxide treated rice straw, respectively. Moreover, ruminal viable and cellulolytic bacterial counts were enhanced by urea and calcium hydroxide treatments. Milk protein and fat concentrations were additionally increased by respective treatments while 3.5% fat-corrected milk was highest; ranking from 2.2% urea + 2.2% calcium hydroxide treated rice straw, 5.5% urea-treated rice straw and urea-treated rice straw fed groups. Based on this study, implications could be made that using 2.2% urea + 2.2% calcium hydroxide treated rice straw for straw treatment could be an alternative treatment to 5.5% urea treatment with regards to its effectiveness and treatment cost for lactating dairy cows.     

Rumen degradation characteristics of sweet potato foliage and performance by local and crossbred calves fed milk and foliage from three cultivars

The study investigated rumen dry matter (DM) degradability characteristics in a completely randomized design and the effects of milk, sweet potato foliage (SPF) from three cultivars (A = TIS-87/0087; B = TIS-8164; C = TIS-2532.OP.1.13), dried brewers' grains (DBG) and cottonseed meal (CSM) as supplements to Panicum maximum (Panicum) for pre-weaned calves in randomized complete block designs. Diet 1 = milk + SPF-A foliage + Panicum, Diet 2 = milk + SPF-B foliage + Panicum, Diet 3 = milk + SPF-C foliage + Panicum, and Diet 4 = milk + DBG & CSM + Panicum (as control). Dry matter (130 ± 0.4 to 864 ± 3.9 g kg^− 1), ash (54 ± 4.2 to 173 ± 2.8 g kg^− 1 DM), OM (827 ± 4.2 to 946 ± 5.7 g kg^− 1 DM), N (7.4 ± 0.6 to 38.6 ± 1.4 g kg^− 1 DM), and NDF (439 ± 1.4 to 774 ± 8.5 g kg^− 1 DM) contents were highly significant (P < 0.01). In Trial I, 16 pre-weaned calves were used over 70 d with milk intake (34.8 ± 4.4 ml kg W^− 0.75 d^− 1), Panicum DMI (22.3 ± 2.77 g kg W^− 0.75 d^− 1), total DMI (35.7 ± 2.83 g kg W^− 0.75 d^− 1), and LWG (198 ± 44.6 g d^− 1) not significantly different (P > 0.05). Supplement DMI varied (P < 0.05) from 11.6 g kg W^− 0.75 d^− 1 in Diet 3 to 16.6 g kg W^− 0.75 d^− 1 in Diet 4. In Trial II, 16 pre-weaned local and crossbred calves were involved over 77 d with initial age of calves, Panicum intake, metabolic DMI, and LWG similar (P > 0.05) among crosses. Birthweight varied (P < 0.05) from 17.3 kg for N'Dama × Jersey crosses to 21.2 kg for White Fulani × Brown Swiss crosses. Supplement and total DMI ranged (P < 0.05) from 172 to 483 g d^− 1 for N'Dama × Jersey crosses to 233 and 674 g d^− 1 for non-inseminate or purebred calves, respectively. The LWG in the White Fulani × Brown Swiss and the N'Dama × Jersey calves were respectively 30% and 24% better, though not significantly, than purebred calves. In Trial III, rumen DM degradability characteristics of feeds in three N'Dama steers showed no significant differences (P > 0.05) in slowly degradable fraction (b) and rate of degradation of b (c). Soluble fraction (a), 48-h degradation, potential degradability (PD) and effective degradability (ED) varied significantly (P < 0.05) and were lowest in Panicum, but similar for foliage among the three sweet potato cultivars. Panicum fodder showed improvements in degradation characteristics with supplementation.     

Genetic trends in a Holstein × other breeds multibreed dairy population in Central Thailand

Genetic variability and genetic trends for 305-day milk yield (MY), 305-day fat yield (FY), and average 305-day fat percent (FP) were evaluated using monthly test-day records from first-lactation cows collected from 1991 to 2005 in 92 farms located in Central Thailand. Estimates of variance and covariance components and breeding values (EBV) were obtained using a multiple-trait animal model. Fixed effects were contemporary group (herd–year–season), calving age, additive genetic group as a function of Holstein fraction, and non-additive genetic group as function of heterosis effect. Random effects were animal and residual. Program ASREML was used to perform computations. Estimates of heritabilities were 0.38 ± 0.10 for MY, 0.25 ± 0.11 for FY, and 0.22 ± 0.11 for FP. Although the difference between the mean MY for cows in 1991 and 2005 was 324.1 kg, the regression of mean cow EBV for MY on year was 6.5 kg/year. Differences between mean cow EBV for FY and FP in 1991 and 2005 and their corresponding regressions of mean FY and FP on year were all near zero. Similarly, mean EBV for sires and dams of cows also showed near zero trends during these years. A factor contributing to the near complete absence of genetic trends was likely the variety of criteria used by producers to choose sires and to keep dams in addition to EBV (e.g., availability of semen, reproductive ability, adaptation to hot and humid conditions). It also appears that high percent Holstein cows failed to reach their production potential under the management, nutrition, and hot and humid climatic conditions in this tropical region. Changes in nutrition and management would be needed for high percent Holstein cows to show an upward trend in Central Thailand.