Effect of tannins and saponins in Samanea saman on rumen environment,milk yield and milk composition in lactating dairy cows

The objective of this study was to investigate the effects of tannins and saponins in Samanea saman on rumen fermentation, milk yield and milk composition in lactating dairy cows. Four multiparous early‐lactating dairy cows (Holstein‐Friesian cross‐bred, 75%) with an initial body weight (BW) of 405 ± 40 kg and 36 ± 8 day in milk were randomly assigned to receive dietary treatments according to a 4 × 4 Latin square design. The four dietary treatments were unsupplemented (control), supplemented with rain tree pod (S. saman) meal (RPM) at 60 g/kg, supplemented with palm oil (PO) at 20 g/kg, and supplemented with RPM at 60 g/kg and PO at 20 g/kg (RPO), of total dry matter (DM) intake. Cows were fed with concentrate diets at a ratio of concentrate to milk yield of 1:2, and chopped 30 g/kg of urea‐treated rice straw was fed ad libitum. The RPM contained condensed tannins and crude saponins at 88 and 141 g/kg of DM respectively. It was found that s upplementation with RPM and/or PO to dairy cows diets did not show negative effect on ruminal pH, blood urea nitrogen and milk urea nitrogen concentration (p > 0.05). However, supplementation with RPM resulted in lower ammonia nitrogen (NH₃‐N) concentration (p < 0.05). In addition, propionic acid and milk production increased while acetic acid, acetic to propionic ratio, methane production, methanogens and protozoal population decreased with RPM and/or PO supplementation. Furthermore, addition of PO and RPO in the diets increased milk fat while supplementation of RPM resulted in greater milk protein and Fibrobacter succinogenes numbers (p < 0.05). The population of Ruminococcus flavefaciens and Ruminococcus albus were not affected by any treatments. The findings on the present study showed that supplementation with RPM and RPO to diets of cows improved the rumen environment and increased milk yield, content of milk protein and milk fat.     

Effect of wood kraft pulp feed on digestibility,ruminal characteristics,and milk production performance in lactating dairy cows

The effect of wood kraft pulp (KP) feed on dietary digestibility, ruminal fluid pH, rumen fermentation characteristics, and milk production performance in lactating dairy cows was examined. Four lactating dairy cows were used for the feeding experiment by the cross‐over design. The control group and KP group were set up as treatments. The control group was fed total mixed ration (TMR) (40% roughage and 60% concentrate) and the KP group was fed TMR containing 12% KP that replaced half of the rolled corn in the control diet. The dry matter intake, digestibility of the feed components, and milk yield were not significantly different between control group and KP group. The number of times that the ruminal fluid pH was below 6.1 tended to decrease in the KP group compared to the control group (p < 0.10). The acetic acid ratio in the ruminal fluid of the KP group increased compared to the control group (p < 0.05) and the propionic acid ratio in the ruminal fluid of the KP group decreased compared to the control group (p < 0.05). The acetate:propionate acid ratio was increased in the KP group compared with the control group (p < 0.05). Lipopolysaccharide levels in the ruminal fluid of the KP group tended to decrease compared to the control group (p < 0.10). Based on these results, it was indicated that the use of KP feed for lactating dairy cows induced the same rumen fermentation characteristics as those in cows given a large amount of roughage without depressing milk productivity. Therefore, KP could be a valuable feed resource substitute for grains, which would also reduce the risk for subacute rumen acidosis.     

High levels of whole raw soya beans in dairy cow diets: digestibility and animal performance

The aim of this study was to evaluate the effects of high levels of whole raw soya beans in the diets of lactating cows. Twelve Holstein dairy cows were used, randomized in three 4 ×  4 balanced and contemporary Latin squares and fed the following diets: (i) control (C), without including whole raw soya beans; (ii) 80 g/kg in DM of whole raw soya beans (G80); (iii) 160 g/kg in DM of whole raw soya beans (G160); and (iv) 240 g/kg in DM of whole raw soya beans (G240). There was significant reduction (p < 0.05) in dry matter intake (kg/day) in cows supplemented with G240 compared with C (23.8 vs. 25.3 respectively). G240 diets presented lower crude protein digestibility (g/kg) (p < 0.05) in comparison with C diet (683 vs. 757 respectively). There was significant effect of experimental rations in nitrogen balance (p < 0.05), G240 diet presenting significant reduction in comparison with the other diets, and faecal excretion of nitrogen was higher for G240 diet. The concentration of ruminal ammoniacal nitrogen was significantly higher (p < 0.05) for cows receiving control diet, compared to other diets. G240 diet resulted in significantly lower milk and protein yield (p < 0.05) in comparison with C diet. Significant C18:2 cis fatty acids were observed in milk concentrations (p < 0.05) for G240 diet. The use of high level of whole raw soya beans in dairy cow diets improves the unsaturated fatty acid profile in milk, and the diets (G80 and G160) led to minor alterations in the digestive processes and animal metabolism.     

Effect of monensin and vitamin E on milk production and composition of lactating dairy cows

Feeding unsaturated oils to lactating dairy cows impair ruminal biohydrogenation (BH) of unsaturated fatty acids (USFA) and increase ruminal outflow of BH intermediates such as trans‐10, cis‐12 CLA that are considered to be potent inhibitors of milk fat synthesis. Supplementing lactating dairy cow’s rations containing plant origin oils with monensin and/or vitamin E may minimise the formation of trans‐10 isomers in the rumen, thereby preventing milk fat depression. Therefore, this study was conducted to evaluate the effects of monensin and vitamin E supplementation in the diets of lactating dairy cows containing whole cottonseed, as the main source of FA on feed intake, milk production and composition, milk fatty acid profile, efficiency of nitrogen (N) utilisation, efficiency of net energy (NE) utilisation and nutrients digestibilities. Four multiparous Holstein lactating dairy cows (86 ± 41 days in milk) were assigned to a balanced 4 × 4 Latin square design. Each experimental period lasted 21 days with a 14 days of treatment adaptation and a 7 days of data collection. The control diet was a total mixed ration (TMR) consisted of 430 g/kg forage and 570 g/kg of a concentrate mixture on dry matter (DM) basis. Cows were randomly assigned to one of the four dietary treatments including control diet (C), control diet supplemented with 150 mg of vitamin E/kg of DM (E), control diet supplemented with 24 mg of monensin/kg of DM (M) and control diet supplemented with 150 mg of vitamin E and 24 mg of monensin/kg of DM (EM). Dry matter intake (DMI) ranged from 19.1 to 19.5 kg/d and was similar among the dietary treatments. Dietary supplementation with vitamin E or monensin had no effect on milk production, milk fat, protein and lactose concentrations, efficiency of utilisation of nitrogen and net energy for lactation (NE_L). Digestibility of DM, organic matter (OM), crude protein (CP) and ether extract (EE) was not affected by the dietary treatments. Digestibility of neutral detergent fibre (NDF) was higher in cows fed with the M and EM diets in relation to those fed the C and E diets. The concentrations of C4:0, C6:0, C8:0, C10:0, C12:0, C14:0, C15:0, trans‐10‐16:1, cis‐9‐16:1, 17:0, 18:0, trans‐11‐18:1, cis‐9‐18:1, cis‐9, trans‐11 conjugated linoleic acid (CLA), trans‐10, cis‐12 CLA, and 18:3n‐3 FA in milk fat were not affected by the dietary supplementations. While feeding the M diet tended to decrease milk fat concentration of C16:0, the milk fat concentration of C18:2n‐6 FA tended to be increased. Dietary supplementation with vitamin E or monensin had no effect on milk fat concentrations of saturated, unsaturated, monounsaturated, polyunsaturated, short chain and long chain FA, but feeding the M diet numerically decreased milk fat concentration of medium chain fatty acids (MCFA). The results showed that vitamin E and/or monensin supplementations did not improve milk fat content and did not minimise the formation of trans‐10 FA isomers in the rumen when whole cottonseed was included in the diet as the main source of fatty acids.     

Effects of Saccharomyces cerevisiae on ruminal pH and microbial fermentation in dairy cows: Yeast supplementation on rumen fermentation

An experiment was conducted with eight ruminally-cannulated cows using a crossover design with 2 periods to determine the effects of yeast supplementation on rumen fermentation. Holstein dairy cows in late lactation were either supplemented with 0.5 g/hd/d of Saccharomyces cerevisiae, an active dry yeast (CNCM-1077, Levucell SC20 (r) SC, Lallemand Animal Nutrition) or not supplemented (control). A basal diet consisting of 60% forage and 40% concentrate (DM basis) was fed once daily to both groups of cows throughout the entire experiment. Ruminal pH was measured continuously every 22 min using a pH probe that was placed in the ventral rumen sac for 6 consecutive days. Volatile fatty acid and ammonia N concentrations in the rumen were measured on days 5 or 6 of the 12-d period for each cow and DM intake was monitored throughout the experiment. Data were analyzed using a mixed-effects model with repeated measures. There were no differences in dry matter intake between treatments. Mean ruminal pH was greater (P < 0.05) when yeast was supplemented (6.53 ± 0.07) compared with the control (6.32 ± 0.07). Average maximum and minimum ruminal pH were also greater (P < 0.05) when yeast was supplemented (7.01 ± 0.09 and 5.97 ± 0.08, respectively) compared with the control (6.80 ± 0.09 and 5.69 ± 0.09, respectively). Time spent under the subacute acidosis threshold, pH less than 5.6, was lower (P < 0.05) with yeast supplementation compared with control cows. No difference was observed for ruminal ammonia N concentrations (mean = 14.0 ± 1.2 mg/dL) between treatments. Total VFA concentration (mM) in the rumen tended to be lower (P = 0.10) in the yeast-supplemented cows (107.3 ± 6.35) than in the control cows (122.4 ± 6.35), which could be related to the greater pH observed with yeast supplementation. Supplementing dairy cows with active dry yeast in the current experiment increased the mean, minimum and maximum ruminal pH; decreased time spent in subacute rumen acidosis, and tended to decrease total VFA concentration in the rumen compared with control cows.     

Effect of dried Sesbania sesban leaves supplementation on milk yield,feed intake,and digestibility of Holstein Friesian X Zebu (Arado) crossbred dairy cows

This experiment was conducted to investigate effect of dried Sesbania sesban leaves supplementation on milk yield, feed intake and digestibility of Holstein Frisian X Zebu (Arado) crossbred dairy cows. Twelve cows at midlactation (155.83?±?4.49 days of lactation), second parity, and 442.21?±?3.40 kg average live body weight were randomly assigned to one of four dietary treatments according to a randomized complete block design. Cows were blocked according to their daily milk yield into three blocks of four animals each. Cows were fed a basal diet (control) or a basal diet supplemented with 1.25 kg/day dried Sesbania sesban leaves, 2 kg/day dried Sesbania sesban leaves and 2.75 kg/day dried Sesbania sesban leaves on a dry matter basis for 8 weeks. Total dry matter intake, nutrient intake, milk yield, dry matter digestibility, and nutrient digestibility showed significant variation among treatments. Cows supplemented with the highest level of Sesbania sesban (2.75 kg/day) had higher total dry matter and nutrient intake. Similarly, cows supplemented with 2 and 2.75 kg/day had higher milk yield than the nonsupplemented cows (up to 11.3 and 16.2%, respectively). Digestibility was lower for the nonsupplemented cows compared to cows supplemented with 2 and 2.75 kg/day dried Sesbania sesban leaves but statistically similar to the cows supplemented with 1.25 kg/day dried Sesbania sesban leaves. Supplementation with 2.75 kg/day Sesbania sesban resulted in higher organic matter digestibility (OMD) compared to the control. Crude protein digestibility (CPD), neutral detergent fiber digestibility (NDFD), and acid detergent fiber digestibility (ADFD) were significantly affected by Sesbania sesban supplementation. The nonsupplemented cows had lower CPD, NDFD, and ADFD. These results indicate that dried Sesbania sesban leaves supplementation to dairy increases total DM intake, digestibility, and milk yield.

     

Feed degradability,rumen fermentation and blood metabolites in response to essential oil addition to fistulated non‐lactating dairy cow diets

The effects of essential oils (EOs) on ruminal nutrient disappearance, rumen fermentation and blood metabolites in fistulated non‐lactating dairy cows were studied. Four fistulated non‐lactaing dairy cows were used in a 4 × 4 Latin square design; the experiment consisted of four periods of 21 days in each period, with the first 14 days for adaptation followed by 7 days of measurement period. Animals were fed 3 kg/day of 21% crude protein (CP) concentrate and ad libitum corn silage. Treatments were: (i) control; (ii) 2 mL Allicin/cow/day; (iii) 2 mL zingiberene/cow/day; and (iv) 2 mL citral/cow/day. The results demonstrated that EOs increased dry matter and neutral detergent fiber degradabilities at 48 and 72 h, but had no effect on acid detergent fiber and CP degradabilities. EOs did not change ruminal pH, ammonia nitrogen, protozoa, volatile fatty acid concentrations and blood glucose but reduced blood urea nitrogen at 4 h.     

日粮添加益生菌对干乳期奶牛生长性能、瘤胃发酵及氮平衡的影响

本研究旨在评估全混合日粮添加益生菌对干乳期奶牛生长性能、瘤胃发酵及氮平衡的影响.试验将体重为(440.92±3.33)kg、平均干乳期为42?d的60头荷斯坦奶牛随机分为2组,每组5个重复,每个重复6头.对照组饲喂玉米-豆粕型全混合日粮,处理组饲喂基础全混合日粮+200?mg/kg益生菌(枯草芽孢杆菌含量:1×106?...     

Effect of the type of silage on milk yield,intake and rumen metabolism of dairy cows grazing swards with low herbage mass

The aim of this study was to evaluate the effect of herbage allowance (HA) and type of silage supplemented (TS) on milk yield, dry matter intake (DMI) and metabolism of dairy cows in early lactation. Thirty‐six Holstein‐Friesian dairy cows were allocated to four treatments derived from an arrangement of two HA (LHA = 17 or HHA = 25 kg of DM/cow/day) and two TS (grass (GS) or maize (MS)). Herbage allowance had no effect on DMI or milk yield. Rumen pH and NH₃‐N concentration were not affected by HA. The efficiency of microbial protein synthesis in the rumen (microbial protein (MP)) was affected by HA with 21.5 and 23.9 g microbial nitrogen per kg ruminal digestible organic matter for LHA and HHA, respectively (P < 0.05). Supplementation with MS showed higher values of milk yield by 2.4 kg/cow/day (P < 0.001), milk protein content by 0.10 % (P < 0.023) and herbage DMI by 2.2 kg/cow/day, and showed lower values for milk urea compared to GS (P < 0.001). The former results suggest that TS had a greater effect on milk yield, total feed intake and energy intake than increase in herbage allowance; however, increase in HA had greater effects on MP than TS.     

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.     

Sainfoin (Onobrychis viciifolia) silage in dairy cow rations reduces ruminal biohydrogenation and increases transfer efficiencies of unsaturated fatty acids from feed to milk

The effects of replacing grass silage by sainfoin silage in a total mixed ration (TMR) based diet on fatty acid (FA) reticular inflow and milk FA profile of dairy cows was investigated. The experiment followed a crossover design with 2 dietary treatments. The control diet consisted of grass silage, corn silage, concentrate and linseed. In the sainfoin diet, half of the grass silage was replaced by a sainfoin silage. Six rumen cannulated lactating multiparous dairy cows with a metabolic body weight of 132.5 ± 3.6 kg BW^0.75, 214 ± 72 d in milk and an average milk production of 23.1 ± 2.8 kg/d were used in the experiment. Cows were paired based on parity and milk production. Within pairs, cows were randomly assigned to either the control diet or the sainfoin diet for 2 experimental periods (29 d per period). In each period, the first 21 d, cows were housed individually in tie-stalls for adaptation, then next 4 d cows were housed individually in climate-controlled respiration chambers to measure CH₄. During the last 4 d, cows were housed individually in tie stalls to measure milk FA profile and determine FA reticular inflow using the reticular sampling technique with Cr-ethylenediaminetetraacetic acid disodium salt dihydrate (EDTA) and Yb-acetate used as digesta flow markers. Although the dietary C18:3n-3 intake was lower (P = 0.025) in the sainfoin diet group, the mono-unsaturated FA reticular inflow was greater (P = 0.042) in cows fed the sainfoin diet. The reticular inflow of trans-9, trans-12-C18:2 and cis-12, trans-10 C18:2 was greater (P ≤ 0.024) in the sainfoin diet group. The cows fed sainfoin diet had a lower (P ≤ 0.038) apparent ruminal biohydrogenation of cis-9-C18:1 and C18:3n-3, compared to the cows fed the control diet. The sainfoin diet group had greater (P ≤ 0.018) C18:3n-3 and cis-9, cis-12-C18:2 proportions in the milk FA profile compared to the control diet group. Transfer efficiencies from feed to milk of C18:2, C18:3n-3 and unsaturated FA were greater (P ≤ 0.0179) for the sainfoin diet. Based on the results, it could be concluded that replacing grass silage by sainfoin silage in dairy cow rations reduces ruminal C18:3n-3 biohydrogenation and improves milk FA profile.     

Effects of partial replacement of barley grain with beet pulp on performance,ruminal fermentation and plasma concentration of metabolites in transition dairy cows

The objective of this study was to determine the effect of partial replacement of barley grain with beet pulp (BP) on dry matter intake (DMI), ruminal fermentation, plasma concentration of metabolites and milk yield of transition dairy cows. Twenty‐four multiparous Holstein cows [735 ± 26 kg of body weights and 3.5 ± 0.05 of body condition score (BCS)] were used in a randomized complete block design. Cows were assigned randomly on day 28 relative to expected parturition date to one of three treatments containing (i) 0% BP, (ii) 25% BP or (iii) 50% BP substituted for barley grain on a DM basis. During the pre‐partum period, DMI and energy intake were greater (P < 0.01) in cows fed the BP diet compared with cows fed the barley grain diet. During the post‐partum period, substituting BP for barley grain caused a response in DMI and energy intake, with the highest amount for the 25% BP diet and lowest for the 50% BP diet (P < 0.01). Milk yield was lowest (P < 0.01) for 50% BP diet than the other treatments. During the post‐partum period, cows fed the 50% BP diets had greater rumen pH, molar proportion of butyrate and acetate: propionate ratio (P < 0.01) in the rumen compared with cows fed the 0% BP diets. In addition, cows fed the BP diets had greater (P < 0.01) plasma β‐hydroxybutyrate and lower plasma glucose (P < 0.05) and blood urinary nitrogen (BUN) (P < 0.01) concentrations than cows fed the barley grain diets. Results showed that substituting BP for barley grain was effective in increasing DMI, but it did not have a significant effect on net energy balance during the post‐partum period. However, replacing BP for barley grain at 50% had adverse effects on DMI, milk yield and metabolic status, as indicated by key blood metabolite concentrations.     

Effect of feeding Acacia nilotica pods to sheep on nutrient digestibility,nitrogen balance,ruminal protozoa and rumen enzymes activity

This study was conducted to evaluate the effect of supplying two levels of Acacia nilotica (A. nilotica) pods to rations of sheep on nutrient digestibility, nitrogen balance and rumen liquor parameters (pH, total protozoa count, protein concentration and enzymes activity). Twelve mature rams (50 ± 1.25 kg B.W.) were distributed into three groups, each with four rams. Animals in group one were considered as a control which fed a basal diet, consisting of concentrate mixture and Egyptian clover. The second group and the third one received the same basal diet with supplying the concentrate mixture by 1.5% and 3.0% of A. nilotica pods meal respectively. The experiment lasted for 3 weeks. It was found that supplementation of A. nilotica pods to the concentrate mixture at a rate of 1.5% and 3.0% significantly improved the total feed intake compared to the control. The digestibility of dry matter and crude fibre was significantly reduced with A. nilotica supplements, whereas the digestibility of crude protein was significantly improved. All of nitrogen intake and N‐retained were significantly increased in rams fed on concentrates with 1.5% and 3.0% A.  nilotica pods when compared to the control. The pH of ruminal fluid was not affected by the dietary treatments. Nevertheless, the total rumen protozoa count was significantly decreased in A. nilotica pods supplemented groups. Also, the rumen protein concentration and the ruminal enzymes activity, especially α‐amylase, cellulase and protease, were lower in A. nilotica pods supplemented treatments. In conclusions, inclusion of low levels of A. nilotica pods (1.5% and 3.0%) in the concentrates can be used as a natural protein protectant in ruminants by forming tannin protein complexes in the rumen to maximize the amino acids available in the lower digestive tract. Also, these levels can increase the protein digestibility as well as the N‐retained in the body .     

Performance of lactating dairy cows fed a diet based on treated rice straw and supplemented with pelleted sweet potato vines

The purpose of this study was to evaluate the effects of sweet potato vine pellet (SWEPP) in concentrate diets on nutrient digestibility and rumen ecology in lactating dairy cows fed on urea-treated rice straw. Three multiparous Holstein crossbred cows in mid-lactation were randomly assigned according to a 3?×?3 Latin square design, and the treatments were as follows: T1 = control (no supplementation), T2 = supplementation of sweet potato vine pellet with 50 g/kg urea (SWEPP I) at 300 g/head/day, and T3 = supplementation of sweet potato pellet with 100 g/kg urea (SWEPP II) at 300 g/head/day, in concentrate diets, respectively. The result revealed that supplementation of SWEPP did not affect feed intake, ruminal pH, and blood urea nitrogen (P?>?0.05). However, apparent digestibilities of organic matter, crude protein, and neutral detergent fiber were higher in SWEPP II than those in others. Furthermore, ruminal ammonia nitrogen (NH₃-N) and milk yield were significantly higher (P?<?0.05) in animals fed with SWEPP II than those fed with SWEPP I and control, respectively. In addition, there were no differences in purine derivatives and microbial nitrogen supply among all the treatments. Based on this study, it could be concluded that SWEPP is a good source of supplement which resulted in significant improvement in apparent digestibility, rumen fermentation, and milk yield in lactating dairy cows fed on urea-treated rice straw.     

Effects of Antidesma thwaitesianum Muell. Arg. pomace as a source of plant secondary compounds on digestibility,rumen environment,hematology, and milk production in dairy cows

Mao pomace meal (MPM) contains condensed tannins and saponins at 92 and 98 g/kg, respectively, and these substances can be used to manipulate ruminal fermentation in ruminant. Four multiparous lactating Holstein cows with 45 ± 5 days in milk were randomly assigned according to a 4 × 4 Latin square design to receive four different levels of MPM supplementation at 0, 100, 200, and 300 g/head/day, respectively. Cows were fed with concentrate diets at 1:1.5 of concentrate to milk yield ratio and urea‐treated (3%) rice straw was fed ad libitum. The results revealed that feed intake, nutrient digestibility, blood urea nitrogen, and hematological parameters were not affected by MPM supplementation (p > 0.05). However, ruminal pH and propionate were increased quadratically (p < 0.05) in cows receiving MPM whereas acetate, acetate to propionate ratio and estimate methane production were decreased (p < 0.05). Supplementation of MPM linearly decreased ruminal ammonia nitrogen and protozoal population at 4 hr postfeeding (p < 0.05). Milk production and milk composition were similar among treatments (p > 0.05). In conclusion, supplementation of MPM at 200 g/head/day could modify ruminal fermentation and reduce methane production without adverse effect on feed intake, digestibility, hematological parameters, and milk production in dairy cows.     

Effects of urea treatment of straw and dietary level of vegetable oil on lactating dairy cows

Four crossbreds (75% Holstein Friesian) lactating dairy cows were used to evaluate the effects of sunflower oil (SFO) levels and roughage source on feed intake, nutrient digestibility, ruminal fermentation, milk yield, and milk composition. Four milking cows with average liveweight of 410 ± 25 kg and 18 ± 11 days in milk were randomly assigned according to a 4 × 4 Latin square design, in a 2 × 2 factorial arrangement, with SFO levels (3% or 6%) in the concentrate and the roughage source [rice straw (RS) or urea-treated RS (UTRS)] being the main factors. Four dietary treatments as (1) 3% SFO + RS, (2) 6% SFO + RS, (3) 3% SFO + UTRS, and (4) 6% SFO + UTRS were offered ad libitum total mixed ration, with a concentrate/roughage ratio of 60:40. The results were found that UTRS as a roughage source significantly increased feed intake, digestibility, concentration of acetic acid in rumen fluid, rumen ammonia–nitrogen, blood–urea nitrogen, milk urea–nitrogen, and milk yield (3.5% fat-corrected milk) compared with cows fed on untreated RS. Supplementation of SFO at 3% in the concentrate-supplemented group having increased dry matter intake, milk fat percentage, and milk yield (3.5% fat-corrected milk) compared with 6% SFO supplementation. However, there were no interaction effects between level of SFO in the concentrate and roughage source in any of the factors studied.     

Effects of substituting kraft pulp with corn silage on dry matter intake,ruminal mat formation,rumen fermentation,and rumination activity in non‐lactating cows

The present study examined the effects of substituting kraft pulp (KP) with corn silage (CS) on dry matter intake (DMI), ruminal mat and rumen fermentation characteristics, and rumination. Four non‐lactating, rumen‐cannulated Holstein cows were fed a CS diet comprising 36% grass silage (GS) and 64% CS or a KP diet comprising 36% GS, 57% KP, and 7% soybean meal. DMI was significantly lower in cows fed the KP diet than in those fed the CS diet (p < 0.05), whereas rumination time did not significantly differ between the treatments. Dry matter content in the rumen immediately before and 3 h after feeding was significantly higher in cows fed the KP diet than in those fed the CS diet (p < 0.05). The consistency and thickness of the ruminal mat did not significantly differ between the treatments. The ruminal mean retention time of feed particles tended to be longer in cows fed the KP diet than in those fed the CS diet (p < 0.10). The ruminal digestion rate of KP was comparable to that of GS and CS. Because ruminal mat was formed and rumination was stimulated, KP was considered to have the equivalent physical effectiveness as CS.     

饲粮添加海南霉素和莫能菌素对奶牛瘤胃发酵特性和氮平衡的影响

本研究旨在探究饲粮添加海南霉素和莫能菌素对奶牛瘤胃发酵特性和氮平衡的影响.选用3头体重为(460.0±20.6)kg、装有永久性瘤胃瘘管的成年荷斯坦奶牛,采用3×3拉丁方试验设计,对照组饲喂基础饲粮,试验组分别饲喂在基础饲粮添加20 mg/d海南霉素和350 mg/d莫能菌素的试验饲粮.结果表明:饲粮添加海南霉素和莫能菌素没有显著影响瘤胃液pH和丁酸含量(P＞0.05),但显著降低了瘤胃液总挥发性脂肪酸浓度、乙酸含量、乙酸/丙酸和氨态氮浓度(P＜0.05).与对照组相比,海南霉素组和莫能菌素组丙酸含量分别提高了16.26％和15.79％(P ＜0.01).饲粮添加海南霉素和莫能菌素显著降低了尿囊素排出量、尿嘌呤衍生物排出量和微生物氮产量(P＜0.05).饲粮添加海南霉素和莫能菌素也降低了粪氮量和尿氮量(P＜0.05),提高了沉积氮量(P＜0.01).与对照组相比,海南霉素组和莫能菌素组的表观氮消化率分别提高了5.61％和7.05％(P =0.03).总之,与莫能菌素相似,饲粮添加海南霉素可以改变瘤胃发酵模式,使其更趋向于丙酸型发酵,并且能够提高氮利用效率.     

Proportions of potatoes and fodder beets selected by dairy cows and the effects of feed choice on nitrogen metabolism

Twenty-three lactating dairy cows were switched from a standard diet to a ration of alfalfa/grass silage and 1 kg rapeseed cake supplemented with raw potatoes and fodder beets allowed on a semi-restricted basis. The effects of feed choice on urinary markers for nitrogen metabolism were evaluated by the Stepwise regression technique. Each kilogram dry matter of potatoes and fodder beets lowered milk urea concentration and also the urinary ratio urea/creatinine to a similar extent, but allantoin and fecal results suggested larger hindgut fermentation and hence lower ruminal microbial protein production with potatoes than with fodder beets. The variation for concentration of urinary constituents associated with animal, sampling day and sampling time suggests multiple sampling within a day as preferable for spot sampling. It is concluded that the reluctance to potatoes by some cows may cause initial difficulties when fed to high yielding cows naïve to the feed.     

Effects of Supplemental Carbohydrate Sources on Lactation Performance, Nitrogen Balance, and Ruminal Fermentation in Dairy Cows Fed Energy-Deficient Total Mixed Rations

The effects of supplemental carbohydrate (CHO) sources on milk yield and composition,nitrogen (N) balance,and ruminal fermentation were evaluated in lactating dairy cows fed energy-deficient total mixed rations (TMR).Fifty-six lactating Holstein cows (36.8 ±3.4 kg/d of milk yield; 152 ±26days in milk [ DIM ] ) were randomly assigned to one of four diets:( 1 ) basal TMR ( control ) ; ( 2 ) basal TMR + 1.25 kg/d sucrose (SUC) ; ( 3 ) basal TMR + 2.12 kg/d steam-flaked corn ( SFC ) ; ( 4 ) basal TMR + 2.23 kg/d wheat (WHE).The trial lasted 70 days,including the first 10 days of adaptation.Simultaneously,a 4 × 4 Latin square trial was conducted with four ruminally cannulated cows of similar DMI (Dry Matter Intake) fed on the above four diets.Each testing period lasted 18 days:15 days for adaptation and 3 days for sampling.Cows fed SUC-,SFC-,and WHE-supplemented diets produced 1.6,2.9,and 0.8 kg/d,respectively,more milk than those on the basal TMR control diet,but the difference was not significant (P =0.160).However,the production of energy-corrected milk of cows fed CHO-supplemented diets improved significantly (P =0.020),and the yield of 4％ fat-corrected milk tended to be higher (P =0.063 ) than in control animals.Percentages of milk protein,lactose and solidsnot-fat (SNF) increased significantly in cows fed CHO-supplemented diets ( P ＜ 0.05 ),and yields of milk protein and SNF were significantly higher (P＜0.05); yields of milk fat and lactose were somewhat higher ( P ＜ 0.10 ).Cows receiving supplementary CHO diets consumed more DM (Dry Matter) ( P =0.023 ) ; however,there was no significant difference in N retention,digestibility,or utilization efficiency among the treatments (P ＞ 0.10 ).The average ruminal pH was lowest in cows supplemented with SUC,while that in cows supplemented with SFC and WHE was only slightly reduced (P =0.025 ).Ruminal NH3-N concentration was highest with no supplementary CHO ( P =0.017 ),and changes in postfeeding time were similar across the diets.Total volatile fatty acid concentration was significantly lower in control animals than in those on SUC- and WHE-supplemented diets ( P =0.001 ) ; significant dietary responses were observed in the concentrations of acetate,butyrate,and branched-chain fatty acids and in the acetate-to-propionate ratio ( P ＜ 0.001 ).These results indicate that supplementation with different CHO sources in energy-deficient diets substantially improved the balance of energy and N in the rumen,altered ruminal fermentation,and improved lactation performance in dairy cows.