Effects of malic acid on feed intake, milk yield, milk components and metabolites in early lactation Holstein dairy cows

The objective of this study was to evaluate the effects of malic acid (MA) on feed intake, milk yield and composition, blood metabolites and energy balance in early lactation Holstein dairy cows from 1 to 63 day in milk (DIM). Twenty-eight multiparous Holstein dairy cows, blocked by lactation number, previous 305-d mature equivalent milk production, and expected calving date, were arranged into four groups in a randomized block design. Treatments were: control (without MA), LMA, MMA and HMA with 70, 140 and 210 g malic acid per cow per day, respectively. The supplement of food grade MA (99.8% of MA) was hand-mixed into the top one-third of the daily ration. Cows were fed ad libitum a total mixed ration consisting of equal proportion of forage and concentrate. Milk yield increased (P = 0.04), but feed intake and milk components were not affected (P > 0.05) by MA supplementation. The energy balance, expressed as the difference between energy input and output, tended to be higher (P = 0.08) for MA supplemented cows during the 63-DIM period MA and supplemented cows showed a trend (P = 0.07) toward less loss of BW during the 63-day period, especially during the first 21-day of lactation. Concentrations of plasma glucose and serum insulin were higher for cows fed LMA, MMA, and HMA relative to control and linearly (P < 0.01) increased with increasing MA supplementation. Concentrations of non-esterified fatty acids (NEFA), beta-hydroxybutyrate (BHBA) and urine ketones were lower for MA-supplemented cows at 7, 14 and 21 DIM of lactation and linearly (P < 0.01) decreased with increasing MA supplementation. Although feed intake was not affected, milk yield increased, MA-supplemented cows experienced higher concentrations of plasma glucose and serum insulin, lower concentrations of plasma BHBA and NEFA, and lower concentrations of urine ketones, suggesting that nutrient digestibilities and energy availability may have been improved.     

Effect of reduced energy density of close-up diets on dry matter intake,lactation performance and energy balance in multiparous Holstein cows

Energy intake prepartum is critically important to health, milk performance, and profitability of dairy cows. The objective of this study was to determine the effect of reduced energy density of close-up diets on dry matter intake (DMI), lactation performance and energy balance (EB) in multiparous Holstein cows which were housed in a free-stall barn and fed for ad libitum intake. Thirty-nine dry cows were blocked and assigned randomly to three groups fed a high energy density diet [HD, n = 13; 6.8 MJ of net energy for lactation (NE_L)/kg; 14.0% crude protein (CP) ], or a middle energy density diet (MD, n = 13; 6.2 MJ NE_L/kg; 14.0% CP), or a low energy density diet (LD, n = 13; 5.4 MJ NE_L/kg; 14.0% CP) from d 21 before expected day of calving. After parturition, all cows were fed the same lactation diet to d 70 in milk (DIM). The DMI and NE_L intake prepartum were decreased by the reduced energy density diets (P < 0.05). The LD group consumed 1.3 kg/d (DM) more diet compared with HD group in the last 24 h before calving. The milk yield and the postpartum DMI were increased by the reduced energy density diet prepartum (P < 0.05). The changes in BCS and BW prepartum and postpartum were not affected by prepartum diets. HD group had higher milk fat content and lower lactose content compared with LD group during the first 3 wk of lactation (P < 0.05). The energy consumption for HD, MD and LD groups were 149.8%, 126.2% and 101.1% of their calculated energy requirements prepartum (P < 0.05), and 72.7%, 73.1% and 75.2% during the first 4 wk postpartum, respectively. In conclusion, the low energy density prepartum diet was effective in controlling NE_L intake prepartum, and was beneficial in increasing DMI and milk yield, and alleviating negative EB postpartum.     

丙酸镁对泌乳早期奶牛体况、泌乳性能和代谢参数的影响

选用36头经产奶牛,根据泌乳期、上一泌乳期305 d产奶量和预产期,采用随机区组设计分为4组,对照组饲喂基础日粮,处理1,2和3组分别在基础日粮基础上添加丙酸镁50,100和150 g/d,研究丙酸镁对泌乳早期奶牛采食量、泌乳性能、血液代谢参数和尿酮浓度的影响。结果表明,添加丙酸镁对奶牛的采食量、乳脂率、乳蛋白率、乳糖率和乳干物质率无显著影响,添加丙酸镁100和150 g/d对产乳量、饲料转化效率、体况及代谢参数有改善,该二处理组产奶量、饲料转化效率、体况评分、能量平衡、血浆葡萄糖和胰岛素浓度均显著高于对照组(P<0.05),而血浆游离脂肪酸和β-羟丁酸浓度显著低于对照组(P<0.05),尿酮浓度(除100 g/d组产后7 d测定值与50 g/d组无显著差异外)显著低于对照组和50 g/d组(P<0.05)。根据试验结果,丙酸镁适宜添加量为100 g/d。     

The change of dry matter intake, milk yield and bone turnover in primiparous cows compared to multiparous cows during early lactation

Data from six primiparous and nine multiparous Holstein cows were used to clarify the difference of Ca and P mobilization between primiparous and multiparous cows during early lactation. The dry matter intake (DMI) of primiparous cows was lower (P < 0.01) than those of multiparous cows. Milk yield was lower in primiparous cows at 7, 14, 21 (P < 0.01), and 28 days (P < 0.05) after parturition. There was no significant difference in milk Ca and P concentrations between primiparous and multiparous cows. There were no significant differences in plasma Ca and P concentrations between primiparous and multiparous cows. The plasma P level at 7 days postpartum in primiparous cows was lower (P < 0.05) than 28 days postpartum. The concentration of plasma osteocalcin (OC) measured as bone formation marker of primiparous cows was significantly higher than multiparous cows (P < 0.01) at 21 and 28 days postpartum. The urinary deoxypyridinoline (DPD) as bone resorption marker of primiparous cows tended to be higher (P < 0.10) than multiparous cows at 21 days after parturition and decreased to the same level as that of multiparae toward the peak lactation. These results show that Ca and P mobilization of primiparous cows are more active than multiparous cows.     

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.     

基于CNCPS6.5的泌乳早期奶牛乳真蛋白质产量对可代谢蛋氨酸供应量的Meta分析

[目的]试验旨在研究泌乳早期奶牛乳真蛋白质产量(MTPY)对可代谢蛋氨酸供应量(mMetS)的剂量效应关系。[方法]在对泌乳早期荷斯坦奶牛真蛋白质产量的影响因素进行主成分分析的基础上,运用SAS的非线性混合模型(NLMIXED),分别以代谢蛋白质中Met百分含量(Met%MP)、可代谢蛋氨酸供给量(mMetS)和mMetS与代谢能(ME)进食量的比值(mMetS/ME)作为自变量,与MTPY的剂量效应关系进行了Logistic参数拟合。[结果]结果表明,以mMetS作为自变量拟合的Logistic模型效果最优。MTPY预测值经残差校正后(MTPY_校正),再与mMetS进行混合模型(MIXED)回归分析,得到预测回归方程MTPY_校正=(951.03±38.2)+(3.05±0.67)×mMetS(R²=0.1912,RMSE=143.2)。[结论]补饲瘤胃保护性蛋氨酸(RP-Met)产品的边际效率会随补饲量的增加而降低,并非恒定不变的。试验设计类型为交叉设计时,对试验的固定效应可能会造成干扰,原因可能与交叉设计的试验期过短...     

Effects of grazing adaptation on herbage intake,milk production,and body weight change in lactating dairy cows after turning out to pasture in early spring

The present study investigated the effects of adaptation to grazing in early spring on the herbage intake, milk production, and body weight changes in lactating dairy cows. The experiment included 12 Holstein lactating cows during early spring. Six cows were allowed to gradually adapt to grazing (ADP) over 10 days. They were allowed to graze on a pasture for 4 h during the first week and for 19 h during the remaining 3 days (adaptation period). During the 10-day period, the remaining six cows were housed in a barn (CON). Cows in both groups received adequate silage, hay, and concentrate during the adaptation period. Subsequently, cows in both groups were allowed to graze together for 19 h for 4 weeks (experimental period). No cow received supplements during the experimental period. In the first week of the experimental period, the ADP cows showed a higher herbage intake than the CON cows. During the subsequent weeks, there were no differences in herbage intake between the two groups. At the start of the experimental period, milk production and body weight of the ADP cows were higher than those of the CON cows, and this difference lasted until the end of the experiment.     

甜菜碱对奶牛采食量、泌乳性能和血液指标的影响

选用20头体重(597±11.8)kg、泌乳天数(88±4.5)d、日产奶(26.3±0.5)kg的经产奶牛,随机分为4组,采用4×4拉丁方设计,研究甜菜碱(0、50、100和150g/d)对泌乳早期奶牛采食量、泌乳性能和血液指标的影响。结果表明:日粮添加甜菜碱对奶牛的采食量、乳蛋白率、乳糖率和血糖浓度无显著影响,100g/d组和150g/d组鲜奶产量显著高于对照组和50g/d组(P<0.05);100g/d组和150g/d组4%乳脂校正乳、能量校正乳和乳脂产量显著高于对照组(P<0.05);100g/d组乳脂率显著高于对照组(P<0.05);100g/d组和150g/d组血浆游离脂肪酸和β-羟丁酸浓度显著低于对照组(P<0.05)。根据以上结果推断,甜菜碱的适宜添加水平为100g/d。     

Effect of lactation stage, season and parity on milk cortisol concentration in Holstein cows

This experiment was designed (1) to study the effects of lactation stage, season, and parity on milk cortisol concentrations in Holstein cows, and (2) to elucidate the relationships between milk yield, quality, and milk cortisol concentration. Subjects of this study were 24 dairy cows kept in a free stall barn. Milk samples were taken on test day in May, August, November, and February. Data of milk yield, quality, and cortisol concentration were collected. Random effects of animals and fixed effects of lactation stage, test day, and parity on milk yield, quality, and cortisol concentration were analyzed using mixed models. We estimated the best linear unbiased prediction of each trait (BLUP) which was an animal-specific value. Correlation among milk yield, quality, and cortisol concentration was calculated using raw data and BLUP. The effect of the lactation stage on milk cortisol concentration was significant: the value observed in early lactation was higher than in other stages. However, the correlation between milk yield and cortisol concentration was low. The beginning of lactation might be a strong stressor for every cow. Calculated with raw data, milk cortisol concentration had respectively significant negative correlation with milk protein contents and solid not-fat contents. Calculated with BLUP, milk cortisol concentration showed a significant and negative correlation with milk protein contents. The lactation stage and milk protein contents should be considered for measurement of milk cortisol concentrations.     

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.     

Levels of milk urea, plasma constituents and rumen liquid ammonia in relation to the feeding of dairy cows during early lactation

The study was undertaken to establish the relationships between milk and plasma urea levels and protein supply, using traditional and new measures of feed protein value. Samples of milk and plasma were taken before morning feeding twice weekly for the first 3 months post partum from 21 multiparous cows and 7 heifers. Samples of rumen fluid were collected every second week. The cows were distributed into 4 different feeding groups. Feeding regimens were factorial with respect to protein content of the concentrates (i.e. Low protein (Lp): 12.5% digestible crude protein (DCP) vs. High protein (Hp): 17.5% DCP) and concentrate allowances (i.e. Low energy (Le): substandard vs. High energy (He): standard). Silage was offered ad libitum. The within-animal coefficients of correlation between milk and plasma urea levels, and between milk urea levels and the levels of ammonia in the rumen fluid wer r = 0.88 (p less than 0.001) and r = 0.75 (p less than 0.001), respectively. Analysis of variance showed the following sources of urea variation to be significant: Protein balance in the rumen (PBV), intake of DCP, intake of amino acids absorbed in the intestine (AAT), intake of fattening feed units, and the individual animal factor. A similar tendency was found for the variation of ammonia in rumen fluid. The coefficients of determination (R2 model) were not increased by introducing protein balance (BADCP), the amount of PBV and AAT in the dry matter ingested, or the protein/energy ratio as alternative parameters of protein intake in the models. The levels of protein or energy intake did not significantly influence the levels of plasma albumin. The correlations between urea levels and other plasma indicators of metabolic status and liver function were generally low.     

甘油代替大麦对泌乳中后期奶牛采食量、产奶量和乳质量的影响

文章旨在确定在不影响牛奶产量、牛奶成分、乳脂肪酸组成和牛奶感官质量的情况下,用不同水平甘油代替大麦对泌乳中后期奶牛的影响。试验选择了40头荷斯坦奶牛,采用4×4拉丁方试验设计。在部分混合日粮中,粗甘油替代大麦的含量分别为日粮干物质的0、6%、12%和18%。每天记录个体产奶量、采食量和挤奶频率,每周分析牛奶成分。对新鲜牛奶和贮藏7 d的牛奶样品进行感官分析。部分混合日粮的摄入量随甘油添加水平由0升高至12%,增加近1 kg,甘油由12%升高至18%,减少约1 kg。甘油水平由0升高至6%时,精料摄入量下降0.5 kg。随着日粮中甘油比例的增加,牛奶产量呈线性下降(P<0.05),而牛奶中的脂肪和蛋白质含量呈上升趋势(P=0.08),导致能量校正乳水平随甘油水平的升高表现为二次曲线效应,其中6%甘油组产量最高,18%甘油组产量最低。蛋白质和乳糖产量随日粮中甘油比例的增加线性下降(P<0.05)。随着日粮甘油比例的增加,牛奶中棕榈酸、油酸、亚油酸、亚麻酸和共轭亚油酸的比例线性下降(P<0.05),而短链和中链脂肪酸的比例大部分呈上升趋势。综上所述,甘油作为一种能量饲料可以在不影响牛奶品质的前提下,在泌乳中后期奶牛日粮中替代大麦的水平高达18%。但日粮甘油水平超过12%时可能会降低能量校正乳的产量。     

Relationship between fat accumulation in the liver and energy intake, milk fat yield and blood metabolites in dairy cows

In the present study, 42 multiparous Holstein cows were used to investigate the relationship between fat accumulation in the liver and dry matter intake, milk yield and blood metabolites. Based on the percentage of fat in the liver cell at 2 weeks post‐parturition, the cows were classified into three groups. These groups were: (i) less than 10% of fat (normal group, n = 29); (ii) 10–20% of fat (mild group, n = 6); and (iii) more than 20% of fat (moderate group, n = 7). The bodyweight of the moderate group was high (771 kg) before calving. The sufficiency rates of total digestible nutrients (TDN) were remarkably decreased (approximately 65%) in early lactation. The milk fat yield and milk fat composition of the moderate group were higher (P < 0.05) than the other groups at 1 and 2 weeks post‐parturition. It was suggested that non‐esterified fatty acids (NEFA) mobilized from adipose tissues was directly used by the mammary gland for synthesis of milk fat. The percentage of bromsulfalein (BSP) retention of the moderate group was high (21.1%) at 30 min, and it showed that the BSP clearance function was significantly decreased. The concentrations of NEFA, β‐hydroxybutyric acid and glucose were appropriate indicators of energy status; however, aspartate aminotransferase, γ‐glutamyl transpeptidase and total bilirubin were not sensitive indicators of a moderate fatty liver. Thus, high‐yielding cows that calve in an overweight condition are more likely to develop excessive fat accumulation in the liver because of great mobilization from adipose tissues post‐parturition. In cows with a moderately fatty liver, a decrease in TDN sufficiency rates, an increase of milk fat yield and a reduction of liver function were observed in early lactation. The increase of serum NEFA and milk fat composition resulting from mobilization of adipose tissues helped to diagnose moderate fatty liver.     

Differences between primiparous and multiparous dairy cows in the inter-relationships between metabolic traits, milk yield and body condition score in the periparturient period

During the early postpartum period dairy cows mobilize fat and muscle to support lactation. This is associated with alterations in blood metabolite and hormone profiles which in turn influence milk yield and fertility. This study developed models to determine how metabolic traits, milk yield and body condition score were inter-related at different times in the periparturient period and to compare these relationships in primiparous (PP, n=188) and multiparous (MP, n=312) cows. Data from four previous studies which included information on blood metabolic parameters, parity, milk yield, body condition score and diet were collated into a single dataset. Coefficients of polynomial equations were calculated for each trait between -1 week pre-calving and week +7 postpartum using residual maximum likelihood modelling. The completed dataset was used in a multiple correlation model to determine how the best fit curves were related to each other over time. PP cows had higher concentrations of insulin-like growth factor-I and lower beta-hydroxybutyrate concentrations throughout, higher leptin concentrations pre-partum and both the peak in non-esterified fatty acids and the nadir in urea concentration occurred earlier after calving. These differences were associated with significantly lower milk production. Leptin concentrations fell at calving and were related to body condition score. Insulin was negatively correlated with yield in MP cows only. In MP cows the relationship between insulin-like growth factor-I and yield switched from negative to positive between weeks +4 and +7. Both beta-hydroxybutyrate and urea were positively related to yield in PP cows. In contrast, in MP cows beta-hydroxybutyrate was negatively correlated with yield and urea was strongly related to body condition score but not yield. These results suggest that there are differences in the control of tissue mobilization between PP and MP cows which may promote nutrient partitioning into growth as well as milk during the first lactation.     

Theoretical turnover rate of the rumen liquid fraction in dairy cows and its relationship to feed intake,rumen fermentation,and milk production

Ruminant animals are able to convert plant materials (grain and the human‐indigestible portion of carbohydrates) to milk and meat. In this conversion, most of the plant materials are digested by rumen fermentation and are changed to short‐chain fatty acids, microbial cells, and methane, which is released into the atmosphere. The relationships among feed, rumen fermentation, and milk production are poorly understood. Here we report a novel indicator of characteristics of rumen fermentation, theoretical turnover rate (TTOR) of the rumen liquid fraction. The TTOR was calculated from the presumed rumen volume (PRV) which is estimated by dividing the methane yield by the methane concentration of rumen fluid. The formula for the TTOR is: TTOR = PRV/body weight^0.75. Our present analyses confirm that the TTOR as an indicator is capable of connecting feed, rumen fermentation, and milk production, because dry matter intake/TTOR showed a strong correlation with milk yield/TTOR. In addition, the TTOR may be related to ruminal pH, as we observed that the ruminal pH decreased as the TTOR increased. We propose that the TTOR is a factor characterizing rumen fermentation and a good indicator of the productivity of ruminants and dysbiosis of the rumen microbiome.     

Effect of restricted suckling on milk yield,composition and flow,udder health,and postpartum anoestrus in grazing Holstein cows

The effect of restricted suckling on milk yield and composition, udder health, and postpartum anoestrus in dairy cows in pasture-based systems, was studied in 32 Holstein multiparous cows and their calves. At calving, each cow–calf pair was randomly assigned to one of two treatments: restricted suckling (RS) of the cows by her own or another calf, twice daily for 30 min or artificial rearing (AR) of the calves with milk obtained from the bulk tank, offered twice a day in buckets. Treatments were applied until week 8 after calving. The diet of the cows consisted of direct grazing in improved pastures, corn silage and a commercial concentrate which was offered at milking. Milk production and composition, udder health, body condition score of the cows, body weight and milk intake of the calves were measured weekly, and the first postpartum ovulation was determined three times a week by ovarian ultrasonography. Cows with RS management had a lower machine-milked milk yield (17.9 vs. 24.8 kg/d), a lower fat percentage (3.21 vs. 4.11%) and 4% fat-corrected milk yield (16.2 vs. 25.7 kg/d), and also a lower average milk flow (1.35 vs. 1.76 kg/min) than cows in the AR treatment. There was no effect of treatment on milk protein percentage or udder health as measured by milk electrical conductivity. The interval from calving to first postpartum ovulation was shorter in the AR cows than in the RS cows (18.5 vs. 21.8 days). The RS calves consumed more milk (7.2 vs. 5.4 kg/d), gained more body weight (0.813 vs. 0.656 kg/d), and had a higher body weight at weaning (84.3 vs. 73.3 kg) than AR calves. Restricted suckling of grazing dairy cows had a negative effect on machine-milked milk yield, fat percentage and 4% fat-corrected milk yield, but had no effect on udder health or on improved weight gain and body weight at weaning of the calves.     

Effect of rumen-protected nutrients on feed intake,body weights,milk yield,and composition in Murrah buffaloes during early lactation

The effect of rumen-protected nutrients (bypass fat, BPF; bypass protein, BPP; or their combination, BPPF) was investigated in Murrah buffaloes during the early stage of lactation. Forty Murrah buffaloes (BW 531.92?±?10.85 kg) just after parturition were randomly distributed into four groups according to parity and milk production. Buffaloes individually fed ration from day 0 to 90 postpartum according to feeding group and nutrient requirement. Control and BPF fed groups received a concentrate mixture, CM1 with 25% rumen-protected protein (using barley, wheat bran, and mustard oil cake), BPP and BPPF groups received a second concentrate mixture, CM2 with 40% rumen-protected protein (using barley, de-oiled rice bran, and cottonseed cake). Bypass fat fed groups (BPF and BPPF) additionally were supplemented with 15 g BPF (Ca salt of long-chain fatty acids) per kg milk yield in their respective concentrate mixtures. Dry matter intake, body weights, body condition score, and total milk yield were similar between groups (P?>?0.05). Fat-corrected milk (FCM) production was improved (14.5%, P?>?0.05) in groups fed BPP and BPPF, while significant (19.45%, P?<?0.05) improvement was observed in BPF-fed group. Overall mean values of milk fat, solid not fat, protein, lactose, and total solids were found to be high (P?<?0.05) in treatment groups as compared with control values. It may be concluded that supplementation with BPP or BPF either alone or in combination positively influences the quality of milk produced in Murrah buffaloes during early lactation and BPF additionally had improvement on the quantitative trait of milk as well.

     

ORIGINAL ARTICLE: Effects of calcium propionate supplementation on lactation performance,energy balance and blood metabolites in early lactation dairy cows

To evaluate the effects of calcium propionate (CaP) supplementation on feed intake, milk yield and milk composition, energy balance, blood metabolites and urine ketones in early lactation Holstein dairy cows from 1 to 63 days in milk (DIM), 32 multiparous Holstein dairy cows, blocked by lactation number, previous 305‐day milk production, and expected calving date, were arranged into four groups in a randomized block design. Treatments were control, LCaP, MCaP and HCaP with 0, 100, 200 and 300 g calcium propionate per cow per day respectively. The supplement of food grade CaP (99.8% of CaP) was hand‐mixed into the top one‐third of the daily ration. Cows were fed ad libitum a total mixed ration consisting of equal proportion of forage and concentrate. Feed intake, milk yield and components were not affected by CaP supplementation. The energy balance, expressed as the difference between energy input and output, tended to be higher (p = 0.08) for CaP‐supplemented cows during the 63‐DIM period, especially during the first 21‐DIM lactation. Calcium propionate‐supplemented cows showed a trend (p = 0.09) towards less loss of body weight (BW) during the 63‐DIM period. Concentrations of glucose in plasma and insulin in serum were higher for cows fed CaP relative to control and linearly (p < 0.01) increased with increasing CaP supplementation. Concentrations of non‐esterified fatty acids (NEFA), beta‐hydroxybutyrate (BHBA) and urine ketones were lower for CaP‐supplemented cows at 7, 14 and 21 DIM of lactation and linearly (p < 0.01) decreased with increasing CaP supplementation. These results indicated that nutrient digestibilities and energy status may have been improved.     

全株玉米青贮、谷草和羊草组合全混合日粮饲喂干奶前期奶牛对其围产期生产性能和血液生化及免疫指标的影响

在研究不同比例全株玉米青贮、谷草和羊草组合日粮饲喂干奶前期奶牛对其围产期生产性能和血液生化及免疫指标的影响。选择健康、体况一致的干奶前期荷斯坦奶牛45头,根据体重、胎次及预产期接近(P>0.05)的原则将奶牛随机分为试验A、B和C组,每组15头。分别以精料、全株玉米青贮、谷草和羊草16∶24∶30∶30(A组)、16∶24∶45∶15(B组)和16∶24∶60∶0(C组)比例配合日粮饲喂。产前2周将3组试验牛转入围产牛群,3个试验组开始饲喂场内同一围产前期和新产牛日粮。试验期88 d。结果表明:1)与C组相比,B组在产后1、2和3周的干物质采食量分别提高10.46%(P<0.05)、7.79%(P<0.05)和5.65%(P<0.05)。除产后1周外,产后2、3周B组的奶牛体况评分分别比C组高6.60%(P<0.05)和9.06%(P<0.05)。2)各试验组的犊牛初生重差异不显著(P>0.05)。试验A、B组初乳免疫球蛋白G(IgG)含量分别比C组提高10.82%(P<0.01)和18.07%(P<0.01)。3)与C组相比,B组产后21 d产奶量提高9.00%(P<0.05),乳非脂固形物率提高2.83%(P<0.05),乳蛋白率提高10.59%(P<0.05),乳糖率提高5.64%(P<0.05)。各试验组间乳脂率和尿素氮无显著差异(P>0.05)。4)分娩当天和产后21 d,B组的血清甘油三酯含量显著低于A和C组(P<0.05),B组的血糖含量显著高于A和C组(P<0.05), B组的血清尿素氮和胰岛素显著低于C组(P<0.05),B组的胰岛素样生长因子I(IGF-I)和总蛋白显著高于C组(P<0.05);在产前7 d和分娩当天,B组的血清免疫球蛋白A(IgA)、免疫球蛋白B(IgM)和IgG显著高于C组(P<0.05);在产后21 d,B组的血清IgM和IgG含量显著高于C组(P<0.05);产前7 d和分娩当天,B组瘦素显著高于C组,而B组的血清非酯化脂肪酸(NEFA)含量显著低于C组(P<0.05);在产前7 d、分娩当天和产后21 d,B组的胆固醇均显著低于C组(P<0.05),B组的血清白蛋白含量显著高于C组,B组谷草转氨酶(AST)和谷丙转氨酶(ALT)也显著低于C组(P<0.05)。各试验组间β-羟丁酸无显著差异(P>0.05)。综合分析,干奶前期饲粮组成和养分水平可影响围产期奶牛的机体代谢和生产性能。在本试验条件下,干奶前期奶牛日粮中精料、全株玉米青贮、谷草和羊草的适宜比例为16∶24∶45∶15。     

Effects of an immunomodulatory feed additive on body weight,production parameters,blood metabolites,and health in multiparous transition Holstein cows

The study investigated the impact of feeding OmniGen‐AF^® (OG; Phibro Animal Health, Quincy, IL) from dry‐off to week 4 of lactation at two doses on production performance and metabolic adaptation of multiparous Holstein cows. Forty‐eight cows were blocked and assigned randomly to three treatments: OG was fed at 0 g/head/day (CON), 60 g/head/day (OG60), or 90 g/head/day (OG90). No difference was observed in dry matter intake (DMI) throughout the experiment, whereas feeding OG tended to decrease the percentage body weight change (PWC) on week 2. Although colostrum yield was not affected by treatment, colostrum IgG production of OG90 tended to be higher than that of CON. OG supplementation did not affect overall milking performance but decreased milk SCC during the first 4 weeks of lactation. In prepartum, OG supplementation decreased the concentrations of serum albumin and calcium, and increased serum globulin. OG supplementation tended to increase serum total protein, globulin, and calcium contents postpartum. Furthermore, reduced incidence of mastitis and udder edema were observed. In conclusion, supplementing cows with OG from dry‐off period reduces or modulates the inflammation responses associated with parturition, potentially resulting in improved postpartum health, while feeding OG more than 60 g/head/day did not warrant further benefits.