Feed intake and production parameters of lactating crossbred cows fed maize-based diets of stover,silage or quality protein silage

Thirty-six Boran × Friesian dairy cows (392 ± 12 kg; mean ± SD) in early parity were used in a randomised complete block design. Cows were blocked by parity into three blocks of 12 animals and offered normal maize (NM) stover (T1), NM silage (T2) or quality protein maize (QPM) silage (T3) basal diets supplemented with a similar concentrate mix. Feed intake, body weight and condition changes and milk yield and composition were assessed. The daily intake of DM, OM, NDF and ADF for cows fed the NM stover-based diet was higher (P < 0.05) than for the cows fed the NM silage and QPM silage-based diets. However, the daily intake of DOM (9.3 kg) and ME (140.8 MJ) for cows on QPM silage-based diet was higher (P < 0.05) than for cows on NM stover-based diet (8.4 kg and 124.2 MJ) and NM silage-based diet (7.9 kg and 119.1 MJ). Body weight of cows was affected (P < 0.05) by the diet, but diet had no effect (P > 0.05) on body condition score, milk yield and milk composition. The digestible organic matter in the NM stover-based diet (724 g/kg DM) was lower (P < 0.05) than that in the NM (770 g/kg DM) and QPM silage-based diet (762 g/kg DM). It was concluded that the performances of the cows on the NM silage and QPM silage diets were similar and were not superior to that of the NM stover-based diet.     

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.     

Effect of feeding different levels of foliage from Cratylia argentea to creole dairy cows on intake, digestibility, milk production and milk composition

The effect of feeding different levels of foliage from Cratylia argentea (Desvaux) O. Kuntze to dairy cows on intake, digestibility, milk production and milk composition was studied in the dry tropics in Nicaragua. The treatments were sorghum silage ad libitum, either unsupplemented or supplemented with 2 kg or 3 kg of Cratylia on a dry matter (DM) basis. Six Bos indicus cows of the Creole Reyna breed, with a mean body weight of 386 (SD 19) kg were used in a replicated 3×3 Latin square design. Supplementation with Cratylia increased (p < 0.05) DM intake from 6.6 to 7.8 and 8.7 kg DM/day and milk production from 3.9 to 5.1 and 5.7 kg/day for sorghum silage alone and supplementation with 2 kg and 3 kg DM of Cratylia, respectively. Milk fat, total solids and crude protein and organoleptic characteristics (smell, taste and colour) were not significantly different among diets. The apparent digestibility coefficients of dry matter, organic matter, neutral detergent fibre and acid detergent fibre were not affected significantly by supplementation with Cratylia. However, crude protein (CP) digestibility increased (p < 0.05) in the diets supplemented with Cratylia compared to sorghum silage alone. In conclusion Cratylia given as a protein supplement to a low-quality diet improved DM intake and CP digestibility of the diet and increased milk production, but did not affect milk composition.     

Milk production in Holstein cows supplemented with different levels of ruminally protected methionine

Forty multiparous cows (599 kg ± 18 kg BW) were fed with a basal diet (19.6% CP, 35% RUP, and 1.7 Mcal kg^− 1 NEl) with alfalfa, corn silage and concentrate (49% forage: 52% concentrate). After calving, cows were randomly assigned to the treatments, which consisted in four levels of ruminally protected methionine (RPM): 0, 8, 16 and 24 g d^− 1 of Mepron®M85 (Degussa Co.). Experiment was conducted for 120 days with measurements of milk production, composition, body weight, body condition score and DM intake every 15 days (3 consecutive days) starting on day 5 postpartum. Data were analyzed with the repeated measures model (four treatments in 8 periods through lactation). No treatment effects were detected on DM intake (20.38 ± 2.51 kg d^− 1), body weight (599.78 ± 19.78 kg), body condition score (2.51 ± 0.19 units) and milk fat. However, milk production and protein yield were increased with addition of RPM (P < 0.01). Milk production responded quadratically to methionine level. Holstein cows with a mean production of 35 kg d^− 1 milk require addition of ruminally protected methionine (16 g d⁻¹) to improve milk production.     

Effect of treating alfalfa silage with pistachio by‐products extract on Saanen dairy goats performance and microbial nitrogen synthesis

A lactation experiment was conducted to determine the influence of addition of pistachio by‐products extract (PBE) to alfalfa silage (AS) on performance, rumen fermentation, milk yield and composition, and microbial nitrogen synthesis. Eight multiparous dairy goats (1.8 ± 0.25 kg of milk yield) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments to compare two types of AS (supplemented with or without PBE) with two levels of dietary crude protein (14% vs. 16% CP). Dietary treatments were (i) AS with 14% CP of DM diet without PBE (14%CP?PBE), (ii) AS with 14% CP of DM diet with PBE (14%CP + PBE), (iii) AS with 16% CP of DM diet without PBE (16%CP?PBE) and (iv) AS with 16% CP of DM diet with PBE (16%CP + PBE). PBE was sprayed on fresh alfalfa at a ratio of 500 ml/kg alfalfa DM to get the final concentration of 1% tannin as tannic acid equivalent on DM basis. Intake of CP was greater (p < 0.01) in goats fed 16% CP diets than those fed 14% CP diets, regardless of PBE supplementation. Supplementation of PBE tended to decrease (p = 0.09) rumen NH₃‐N concentration regardless of the level of CP in the diet. Supplementation of PBE tended (p = 0.09) to decrease total purine derivatives regardless of the level of CP in the diet with no significant change in microbial nitrogen supply. Efficiency of microbial nitrogen synthesis (EMNS) had a tendency (p = 0.07) to decrease in PBE supplemented diets. There was also a tendency (p = 0.10) for more EMNS in 14% CP fed goats than those fed 16% CP diets. Therefore, AS supplemented with PBE may lead to less concentration of ruminal NH₃‐N because of decreased degradation of CP by rumen micro‐organisms in response to pistachio by‐products tannins.     

Effect of concentrate crude protein level on grass silage intake, milk yield and nutrient utilisation by dairy cows in early lactation.

Twenty-one multiparous dairy cows were fed concentrates containing three levels (119, 154 and 191 g/kg DM) of crude protein (CP) during the first ten weeks of lactation. Part of the grain and molassed sugar beat pulp was substituted with 0% (RSM0), 15% (RSM15) or 30% (RSM30) repeseed meal. Wilted grass silage was fed ad libitum after calving. The average response between RSM0 and RSM15 was +1.66 kg milk/d per percentage unit change in concentrate CP content. No further response occurred between RSM15 and RSM30. The positive effect of RSM inclusion was seen throughout the experimental period and was associated with increased plasma non esterified fatty acids (NEFA) and decreased plasma insulin concentration one week after calving, and higher efficiency of metabolisable energy utilisation for milk production. Digestibility of the diet remained unaffected. Milk and plasma urea tended to increase with RSM30 indicating excessive supply of rumen degradable protein. Because of the limited potential of cows to compensate for a deficit in feed protein supply by mobilising tissue protein, a substantial milk yield response can be achieved with a moderate level of protein supplementation during early lactation.     

Oat silage for grazing dairy cows in small-scale dairy systems in the highlands of central Mexico

The objective was to evaluate the provision of oat silage (Avena sativa) to supplement grazing dairy cows on pastures of perennial ryegrass (Lolium perenne), festulolium (Lolium multiflorum × Festuca pratense) and white clover (Trifolium repens) during the dry season when pasture growth is limited. The experimental design was a 3 × 3 Latin square replicated three times, with nine milking Holstein cows (mean live weight 496.2 ± 33.6 kg and daily milk yield 14.8 ± 2.8 kg cow^?1) under on-farm participatory rural research. Experimental periods were 14 d. Simulated grazing samples of pasture herbage were analysed for chemical composition, sward height recorded and net herbage accumulation determined from exclusion cages. Treatments were the inclusion of oat silage at T0 = 0 kg DM cow^?1 d^?1 of oat silage, T3 = 3 kg DM cow^?1 d^?1 of oat silage, and T6 = 6 kg DM cow^?1 d^?1 of oat silage, plus 5.0 kg fresh weight commercial concentrate and 9 h of continuous grazing. Animal variables were milk yield and composition, live weight and body condition score. Feeding costs were calculated. Mean milk yield was 18.9 ± 0.27 kg cow^?1 d^?1 with no differences in animal variables (p > 0.05), but feeding costs per kilogram milk increased 25% for T3 and 50% for T6. Oat silage supplementation is only viable under difficult grazing conditions.     

Sorghum silage supplemented with crambe meal improves dry matter intake and milk production in crossbred Holstein cows

We studied the feed intake and milk production of Holstein × Zebu crossbred cows fed sorghum silage diets and concentrates, with and without the addition of crambe meal. Using a change-over design for a total of 120 days, eight cows were fed two diets (concentrates + silages with and without crambe meal) in four 30-day periods, with four replications (animals). The crambe meal diet increased (P < 0.05) the dry matter intake (DMI), crude protein intake (CPI), and non-fibrous carbohydrates intake (NFCI) as well as milk production (4.3%). No difference was noted (P > 0.05) for the milk composition between the treatments. Crambe meal as an additive in sorghum silage (100 g/kg in natural matter) showed a great potential for introduction in dairy farming as it substantially increases CP intake, does not reduce food intake, raises animal productivity, and does not affect milk composition.     

Evaluation of total mixed ration silage with brewers grains for dairy buffalo in Tarai,Nepal

To investigate the effects of total mixed ration (TMR) silage, which contained brewers grain and rice straw as a substitute for conventional concentrate on feed intake and milk production in middle‐to‐late lactation buffaloes, four multiparous Murrah buffaloes were assigned to a 3 × 3 Latin square design experiment. The TMR silage, which had higher neutral and acid detergent fiber contents and digestibility than concentrate (P < 0.05) and similar crude protein (CP) and total digestible nutrient (TDN) contents with concentrate were used for the lactation experiment. The treatments were control (CTL) fed concentrate at 0.6% of body weight (BW), and T1 and T2 fed the TMR silage at 0.6 and 1.2% of BW on a dry matter (DM) basis, respectively, with rice straw ad libitum. Daily intakes of DM, CP and TDN, and BW change were higher in T2 than in CTL and T1 (P < 0.05). Although milk composition did not differ among the treatments, milk yield (MY) was higher in T2 (P < 0.05). There were no significant differences in MY/DM intake and MY/TDN intake among the treatments. The increase of BW and MY in middle‐to‐late lactation buffaloes might have been due to high TDN intake from supplementary TMR silage.     

Effect of feeding dried distillers' grains with solubles on milk yield and milk composition of cows in mid‐lactation and digestibility in sheep

We evaluated the effect of three sources of dried distillers' grains with solubles (DDGS) in diets of mid‐lactating dairy cows on milk production and milk composition and on digestibility in sheep. DDGS from wheat, corn and barley (DDGS₁), wheat and corn (DDGS₂) and wheat (DDGS₃) were studied and compared with a rapeseed meal (RSM). RSM and DDGS were characterized through in situ crude protein (CP) degradability. Nutrient digestibility was determined in sheep. Twenty‐four multiparous cows were used in a 4 × 4 Latin square design with 28‐day periods. Treatments included total mixed rations containing as primary protein sources RSM (control), DDGS₁ (D1), DDGS₂ (D2) or DDGS₃ (D3). RSM contained less rapidly degradable CP (fraction a), more potentially degradable CP (fraction b) and more rumen undegradable CP (UDP) than the three DDGS. In vivo digestibility of RSM organic matter was similar to DDGS. Calculated net energy for lactation (NE_L) was lower for RSM (7.4 MJ/kg DM) than for DDGS, which averaged 7.7 MJ/kg DM. Cows' dry matter intake did not differ between diets (21.7 kg/day). Cows fed D1 yielded more milk than those fed D3 (31.7 vs. 30.4 kg/day); no differences were found between control and DDGS diets (31.3 vs. 31.1 kg/day). Energy‐corrected milk was similar among diets (31.2 kg/day). Diets affected neither milk fat concentration (4.0%) nor milk fat yield (1.24 kg/day). Milk protein yield of control (1.12 kg/day) was significantly higher than D3 (1.06 kg/day) but not different form D1 and D2 (1.08 kg/day each). Feeding DDGS significantly increased milk lactose concentration (4.91%) in relation to control (4.81%). DDGS can be a suitable feed in relation to RSM and can be fed up to 4 kg dry matter per day in rations of dairy cows in mid‐lactation. However, high variation of protein and energy values of DDGS should be considered when included in diets of dairy cows.     

Effect of pasture allowance and supplementation with maize silage and concentrates differing in crude protein concentration on milk production and nitrogen excretion by dairy cows

Sixty cows (40 multiparous and 20 primiparous) averaging 140 days in milk (DIM) were assigned to five treatments to evaluate the effect of pasture allowance and supplements of a) maize silage b) high crude protein concentrate and, c) low crude protein concentrate on milk production and nitrogen (N) excretion. Two of the treatments (HG and LG) were offered herbage only (allowances of 20 and 15 kg dry matter (DM) per cow/day, respectively) while the remaining three treatments were offered a herbage allowance of 15 kg DM per cow/day plus 4 kg DM per cow/day of maize silage (M), a high CP concentrate (CP concentration of 194 g/kg DM) (HC), or citrus pulp (CP concentration of 69 g/kg DM) (LC). Total DM intake (DMI) was similar for HG, M, HC, and LC but was lower for LG (15.2 kg DM per cow/day) than HC (17.4 kg DM per cow/day). The reduction in pasture DMI per kg of supplement DM ingested was 0.44, 0.45, and 0.54 kg for cows offered maize silage, high CP concentrate, and low CP concentrate, respectively. Milk yield was greater for the supplemented treatments (23.7–24.7 kg/day) than for LG (20.7 kg/day) but not for HG (23.2 kg/day). Milk fat concentration was greater for HC (35.3 g/kg) than for HG, M, and LC but not greater than LG, while milk protein concentration was greater for HG (34.8 g/kg) than for LG and HC but not greater than M and LC. The greatest levels of N and PDIN intake were recorded for HG (662 and 2502 g/day) and HC (654 and 2506 g/day) which were greater than LC but not greater than LG and M. Treatment HC recorded the highest PDIE intake (1743 g/day) which was greater than LG, M and LC but not greater than HG. Output of N in milk was greater on HC (134 g/day) than on LG but was not greater than on HG, M, and LC. Faecal N excretion was greater on HG (171 g/day) than on all other treatments while estimated urinary N excretion was greater on HG and HC than LC (320 g/day). Treatment LC had a higher proportion of N output in milk (0.23) than treatment LG but not higher than HG, M and HC treatments. Urinary N expressed as a proportion of total N excretion was lower for HG (0.68) than all other treatments. The results of this study show that there is a large response in milk production to supplementing cows on a restricted grass allowance and that cows offered low CP supplements had similar levels of production to those offered high CP supplements. Nitrogen utilisation was improved by offering supplements of lower CP content.     

Apparent metabolisable energy and amino acid digestibility of microalgae Spirulina platensis as an ingredient in broiler chicken diets

ABSTRACT

1. This work investigates the apparent metabolisable energy (AME), its nitrogen-corrected form (AMEn) and amino acid (AA) digestibility coefficients of the microalgae Spirulina platensis as an ingredient in broiler chicken diets.

2. One group of birds was fed with a basal control diet (BD), and another was fed with a test diet composed of the BD with the addition of the microalgae at a proportion of 200 g/kg. AME and AMEn were assessed by total excreta collection and indigestibility analysis using acid-insoluble ash (AIA) as a marker.

3. The microalgae comprised 888.0 g/kg dry matter (DM), 18.42 MJ/kg gross energy, 514.7 g/kg crude protein, 9.9 g/kg ether extract, 10.6 g/kg crude fibre, 94.4 g/kg ash, 3.1 g/kg Ca and 11.0 g/kg P.

4. The values obtained for AME (13.48 MJ/kg DM) and AMEn (11.72 MJ/kg DM) were higher (p < 0.01) than those obtained using the AIA method (9.39–8.29 MJ/kg DM). The microalgae ileal digestibility coefficients were 0.80 ± 0.04 and 0.78 ± 0.04 for essential and non-essential AA, respectively.

5. Overall, the metabolisable energy content and digestibility of AA for S. platensis indicated that the microalgae are potentially an alternative nutrient source for broilers. The AIA method underestimated AME and AMEn in comparison to the total excreta collection method.     

Effects of a Brown‐midrib corn hybrid on nutrient digestibility in wethers and on dry matter intake,performance, rumen and blood variables in dairy cows

The aim of the present trials was to determine the effect of an experimental Brown‐midrib (Bm) corn hybrid in relation to a commercial corn hybrid (Con) on digestibility in wethers and on dry matter intake (DMI), milk yield and milk composition in dairy cows. Digestibility of crude fibre (CF), neutral detergent fibre (NDFom) and acid detergent fibre (ADFom) were higher for Bm (CF Con: 57.8%; Bm: 67.2%; NDFom Con: 56.8%; Bm: 64.8%; ADFom Con: 52.0%; Bm: 63.9%), but concentration of net energy for lactation did not differ (Con: 6.4 MJ/kg DM; Bm: 6.3 MJ/kg DM). A total of 64 lactating German Holstein cows were assigned to one of the two dietary treatments Con or Bm according to milk yield, lactation number, days in milk and live weight. In Trial 1, cows were fed a total mixed ration consisting of 50% corn silage (Con or Bm) and 50% concentrate on dry matter (DM) basis. In Trial 2, the same animals were fed the respective silage for ad libitum intake and 5.3 kg of concentrate DM per animal per day. In Trial 1, DMI and milk‐fat content were decreased significantly for the Bm‐treatment (DMI Con: 22.5 kg/day; Bm: 21.5 kg/day; milk fat Con: 3.8%; Bm: 3.3%). In Trial 2, milk yield and fat‐corrected milk (FCM) were increased significantly, whereas milk‐fat% was decreased significantly (milk yield Con: 25.8 kg/day; Bm: 29.4 kg/day; FCM Con: 27.2 kg/day; Bm: 29.6 kg/day; fat Con: 4.4%; Bm: 4.0%). Diets did not influence ruminal pH or temperature. Diets, furthermore, did not influence rumination in either trial. Additional research on digestibility and rumen fermentation should, however, be carried out using dairy cows at respective intake levels as trials with wethers cannot be transferred to high‐yielding ad libitum fed cows.     

Relationship between milk fatty acid composition and dietary roughage source in dairy cows

According to a 2 × 2 crossover design, 14 Holstein dairy cows were fed two isoenergetic diets based on either grass hay (GH) or maize silage (MS). Milk samples were collected during the third week of each period, and fatty acid (FA) profiles were analyzed using gas chromatography. The data obtained were subjected to ANOVA. Dietary treatment had no effect on either dry matter intake or milk yield. Milk from animals fed the GH-diet contained lower concentrations of saturated FAs (61.9 vs. 63.4% of total FAs; P < 0.05) and higher levels of polyunsaturated FAs (PUFAs) (6.1 vs. 5.8; P < 0.01). Feeding additional hay also increased conjugated linoleic acid and n-3 FA levels and decreased C16:0 levels. Increases in both PUFAs and n-3 FAs resulted in lower (P < 0.01) atherogenic and thrombogenic indices in milk from animals fed the GH diet compared with those fed the MS diet. A complete substitution of GH for MS appeared to improve milk FA profiles, even using different types of concentrates to provide a balanced diet.

     

Dairy cows fed on tropical legume forages: effects on milk yield,nutrients use efficiency and profitability

Two trials with multiparous dairy cows were conducted. Experiment 1 tested the effects of increasing forage proportion in the diet (500, 600, and 700 g/kg DM) when a mixed sorghum (Sorghum bicolor) and jackbean (Cannavalia ensiformis) silage was used as forage. Experiment 2 studied the substitution of sorghum silage and soybean meal by jackbean silage or fresh cowpea (Vigna unguiculata) forage in the diet. All diets were iso-energetic and iso-proteic. In each experiment, 30 cows were used and separated into three groups. In experiment 1, there were no differences in dry matter intake (DMI), milk yield (MY), or apparent total tract digestibility (aTTd) among the three diets, but milk fat content increased with increasing forage proportion, even though the similar neutral detergent fiber of all diets. Nitrogen use efficiency was highest in the diet containing 600 g forage/kg DM, and some evidence was observed for a better profitability with this forage proportion. In experiment 2, feeding legumes increased DMI despite no effects on aTTd. Milk yield increased in line with DMI, with a larger increase for the fresh cowpea. Nitrogen use efficiency and milk composition were not affected by the diets. The increased MY and lower feed costs increased the economic benefits when feeding legumes, particularly when feeding fresh cowpea. Feeding fresh cowpea or jackbean silage to dairy cows appears to be an alternative to soybean as protein source, ideally at a forage proportions of 600 g/kg DM, without altering milk yield and quality and increasing the farm profitability.     

Effect of total mixed ration silage containing agricultural by-products with the fermented juice of epiphytic lactic acid bacteria on rumen fermentation and nitrogen balance in ewes

The goal of this study was to determine the effects of the fermented juice of epiphytic lactic acid bacteria (FJLB) on the quality of total mixed ration (TMR) silage containing agricultural by-products, its digestibility, rumen fermentation, and nitrogen balance in ewes. TMR was prepared from rice straw, corn stover silage, brewer grain, tofu waste, steam-flaked corn, and a mineral mixture. The treatments consisted of silage additives added to TMR: CON (no silage additive), FJLB, COM (commercial additive), and MIX (FJLB + COM). Four cannulated ewes were assigned to the 4 × 4 Latin square design. The MIX treatment produced a lower (P < 0.01) pH than did the CON and FJLB treatments and a higher (P < 0.01) lactic acid concentration than did the other treatments. The fiber content in the COM treatment was lower (P < 0.05) than that in the other treatments. The FJLB treatment had similar fermentation quality and chemical composition to those of the CON and COM treatments in all parameters observed. Although the silage quality index (Fleig point) was higher in the MIX and COM treatments than in the CON treatment, all silages had good quality. No silage additives affected intake, digestibility, rumen fermentation, or nitrogen balance. In conclusion, the TMR silage prepared from agricultural by-products mixed with wet-type food by-products with or without FJLB added resulted in well-preserved fermentation, and this product might be used as a ruminant feed.

     

Effects of maturity stage and feeding strategy of whole crop barley silage on intake, digestibility and milk production in dairy cows

Five diets containing concentrate, grass silage and whole crop barley silage (WCBS) harvested at different maturity stages were fed to 15 multiparous dairy cows in an incomplete change-over design over three periods. Three diets contained 10.7 kg dry matter (DM) concentrate, 4 kg DM grass silage, and ad libitum access to WCBS harvested at either the heading stage (B1), the early milk stage (B2) or the early dough stage (B3) of maturity. The other two diets contained 10.7 kg DM concentrate, whereas grass silage and WCBS at heading were mixed at two different ratios with a DM content of WCBS of either 0.30 (M1) or 0.70 (M2), and the mixtures were fed ad libitum. Intakes of DM (kg day^− 1: B1 = 21.0, B2 = 20.6 and B3 = 20.0) and neutral detergent fibre (NDF; kg day^− 1: B1 = 7.0, B2 = 6.4 and B3 = 6.3) decreased, whereas starch intake increased (kg day^− 1: B1 = 3.1, B2 = 3.5 and B3 = 4.0) with increasing maturity at harvest. The apparent organic matter (OM) digestibility (g kg^− 1: B1 = 800, B2 = 774 and B3 = 729) decreased with increasing maturity stage, and consequently so did the digestible OM intake. Milk (kg day^− 1: B1 = 27.2, B2 = 26.1 and B3 = 25.9) and energy corrected milk (ECM; kg day^− 1: B1 = 31.0, B2 = 29.4 and B3 = 28.2) yields, and protein concentration (g kg^− 1: B1 = 37.1, B2 = 36.4 and B3 = 36.0) decreased with increasing maturity stage of the WCBS. When cows were fed diet B3 the milk fat concentration decreased (46.4 g kg^− 1) compared to diets B1 (49.3 g kg^− 1) and B2 (49.4 g kg^− 1). The difference in ECM yield between diets B1 and B3 was due to a combined effect of lower milk yield, and lower protein and fat concentrations. This was caused by the higher starch and lower NDF intakes with diet B3, which decreased the milk fat concentration. Moreover, a lower energy intake of diet B3 due to lower OM digestibility decreased milk protein concentration and milk yield. Mixing WCBS at the heading stage with grass silage (M2) decreased digestibility, compared to feeding the forages separately (B1). However, the differences were small and may be a result of soil contamination at harvest of some of the silages, which made the method with using incomplete faecal collection and internal marker acid insoluble ash less reliable. Including WCBS at the heading stage at 0.30 or 0.70 of forage DM did not affect DM intake or diet digestibility, probably because the grass silage in the study was very similar in energy content to the WCBS harvested at heading.     

Brown midrib-3 corn silage improves digestion but not performance of growing beef steers

The brown midrib-3 (bm3) gene mutation has been incorporated into corn plants to potentially improve fiber digestibility. The objectives of this study were to determine the effect of bm3 corn silage on digestion and performance of growing beef steers and to determine whether limiting intake would further enhance fiber digestibility of bm3 corn silage. A bm3 hybrid and its isogeneic normal counterpart were harvested at three-quarters kernel milk line. Neutral detergent fiber, ADF, and ADL were 4.5, 6.9, and 1.9 units lower, respectively, and DM was 5.4 units higher for bm3 than for normal silage. In Trial 1, eight ruminally fistulated Angus crossbred steers (224 +/- 24 kg) were randomly assigned to a 2 x 2 factorial arrangement of treatments in a replicated 4 x 4 Latin square design. Steers had ad libitum feed access or were restricted to 80% of ad libitum intake of diets containing 86% normal corn silage (Control) or bm3 corn silage (BMCS). The remainder of the diets consisted of soybean meal, urea, monensin, vitamins, and minerals. Dry matter intake was greater (P < 0.01) for steers offered ad libitum access to BMCS than for those with ad libitum access to the Control diet. The BMCS treatment resulted in improved (P < 0.05) apparent total-tract digestibility of DM, OM, NDF, and ADF. Mean concentration of total VFA and molar proportions of acetate were increased (P < 0.05) by feeding BMCS. There tended to be a DMI x hybrid interaction (P = 0.16) for apparent total-tract digestibility of NDF. When diets were offered ad libitum, BMCS increased NDF digestibility by 10.5 percentage units compared with Control, but, when DMI was limited, BMCS increased NDF digestibility by 15.8 percentage units. In Trial 2, 128 steer contemporaries of those used in Trial 1 (245 +/- 13 kg) were offered ad libitum access to BMCS or Control diets as used in Trial 1. After a 112-d treatment period, concentrate in the diet was increased, and all steers were fed a common finishing diet. During the 112-d treatment period, steers receiving BMCS consumed 0.45 kg more DM/d (P < 0.05) and had similar ADG (P > 0.10), compared with those steers receiving the Control silage. This resulted in poorer (P < 0.01) feed efficiency for steers receiving BMCS. Finishing phase and overall performance of the steers was not different (P > 0.10) due to treatment. Although feeding BMCS in growth-phase diets resulted in increased daily DMI and improved digestibility of DM and fiber, it did not result in improved steer feedlot ADG compared with Control silage.     

Effects of three different concentrate proportions and rapeseed meal supplement to grass silage on animal performance of dairy-breed bulls with TMR feeding

A 3 × 2 factorial design with growing dairy-breed bulls was used to study the effects on animal performance of (1) proportion of concentrate (rolled barley) in the diet, and (2) inclusion of rapeseed meal (RSM) in the barley-based concentrate in a total mixed ration (TMR). The interactions between concentrate proportion and RSM supplement were also examined.Three feeding experiments comprised in total of 84 Finnish Ayrshire bulls and 6 Friesian bulls. The bulls were fed TMR ad libitum. The three concentrate proportions were 300 (L), 500 (M) and 700 (H) g/kg dry matter (DM), fed without RSM (RSM−) or with RSM (RSM+). Rapeseed meal was given so that the crude protein (CP) content of the concentrate was raised to 160 g/kg DM in the RSM+ diets. In the RSM− diets the CP content of the concentrate was 128 g/kg DM, so the CP content increased 25% with RSM supplementation. Increasing the proportion of concentrate led to a linear improvement in daily live weight gain (LWG) (P < 0.05), but there were no significant treatment differences in the DM intake (kg/d). Increasing the proportion of concentrate also led to significantly higher CP (P < 0.001) and phosphorus (P) (P < 0.001) supply and significantly improved DM and organic matter (OM) digestibility (P < 0.001). However, the digestibility of neutral detergent fibre (NDF) decreased (P < 0.001) as the proportion of concentrate increased. The feed conversion rate (kg DM/kg LWG) decreased significantly with increasing concentrate proportion (P < 0.001). Rapeseed meal supplement had no effect on animal performance, but the supply of CP (P < 0.01) and P (P < 0.001) was higher when RSM was included in the diet. The CP (P < 0.001) and NDF (P < 0.05) digestibilities were also higher for the RSM+ diets than for the RSM− diets. Because RSM at the concentration used did not affect animal performance, there is no reason to use RSM supplementation for finishing dairy bulls when there is good quality grass silage and barley-based concentrate in the TMR ration. This study also shows that there is a need to update the Finnish feeding recommendations for dairy-breed growing bulls, and extra calculations are needed for the energy and protein supply of growing dairy bulls.     

奶牛产奶前期营养调控研究

通过对奶牛日粮代谢能、粗蛋白质和粗饲料类型3个营养因素对产奶前期奶牛100d产奶量影响的测定,确定日粮代谢能是起主导作用的因素。本试验ME:11.0MJ/kg,CP:12.0,粗饲料为全株玉米青贮饲料加玉米秸,奶牛100d产奶量可达到2907kg,平均日产奶29.07kg/d,全日粮料奶比为0.69:1,相当于精饲料产奶比0.31:1。根据上述试验结果和吉林西部的气候与饲料资源特点,笔者推荐在奶牛产奶前期生产中使用ME:10.0MJ/kg,CP:10.5的日粮,尽量不使用稻草作为奶牛产奶前期的主要粗饲料。