Assessment of Lactational Performance in Dairy Cows Receiving a Rumen Protected B Vitamin Blend during Lactation: Part 1: A Meta-Analysis of 50 Studies

The objective of this research was to evaluate the impact of a dietary supplemental rumen protected B vitamin blend (RPBV: Folic acid, B12, pyridoxine, pantothenic acid, and biotin;Jefo, St. Hyacinthe, QC Canada) on milk, fat, and protein yield in cows past peak lactation. Results from 50 double reversal design trials (control-test-control) were evaluated using meta-analyses. All herds participated in monthly milk recording services, and all were Holstein herds. Within each of the 50 trials, cows included in the statistical analysis were over 45 days in milk (DIM) at the first milk test, averaged 159 ± 26 DIM on the first test date, and were available for all milk collection periods. A total of 6483 cows from 7 countries were represented in the 50 studies, with an average herd size of 129.7 ± 118.0. Meta-analyses were conducted to determine effect size for milk, fat, and protein yield based on the treatment differences and standard errors (SE) from the individual trials. Results indicated that dairy cows responded positively to the inclusion of the rumen protected B vitamin blend. Forest plots revealed trial-to-trial variation and might be related to age, level of milk production, and stage of lactation of the cows.

Assessment of Lactational Performance in Dairy Cows Receiving a Rumen Protected B Vitamin Blend during Lactation: Part 2: A Regression Analysis of 50 Studies

A previous series of meta-analyses demonstrated that a protected blend of B vitamins (RPBV: folic acid, B12, pyridoxine, pantothenic acid, and biotin;Jefo, St. Hyacinthe, QC, Canada) improved milk fat and protein yield, with variation in the extent of the response. These results represent additional analyses of the same dataset to determine if the degree of response to RPVB on milk, fat and protein yield might be related to the level of production, lactation number, or days in milk (DIM). Results from 50 on-farm switchback trials conducted in 7 countries between 2005 and 2015 were included in the analysis. All herds participated in monthly milk recording services, and all were Holstein herds. A total of 6483 cows, averaging 163 DIM on the first test date, participated in the studies. Data were analyzed using regression models that accounted for the effects of trial, period, days in milk (DIM) and lactation number on milk and component yield. Milk yield and fat yield increased with B vitamin inclusion, and the extent of change was determined to increase with lactation number (P < 0.05). Protein yield increased with the RPBV and was unaffected by lactation number (P < 0.05) Responses to the RPBV occurred throughout lactation but were found to decline with DIM for milk, fat and protein yield. The global equation revealed that milk yield with the rumen-protected B vitamin blend = 4.05 + [0.917 × control milk] - [0.0063 × DIM] + [0.246 × Lactation number] (R2 = 0.798) The use of regression models allows changes in milk, fat and protein yields with the rumen-protected B vitamin blend to be more accurately predicted.

日粮中添加过瘤胃保护B族维生素对奶牛健康、产奶量和繁殖性能的影响

围产期日粮中添加过瘤胃保护B族维生素对奶牛健康、产奶量和繁殖性能都会产生影响。试验结果表明,添加过瘤胃保护B族维生素可以显著降低刚分娩奶牛亚临床酮病的发病率、奶牛平均人工授精成本以及泌乳190天内的淘汰率(P<0.05);显著增加乳脂率和泌乳150天怀孕率(P<0.05);胎衣不下的发病率从18.5%减少到16.0%,但是差异不显著。这说明在围产期日粮中添加过瘤胃保护B族维生素可以提高牛奶乳脂率、奶牛健康状况以及繁殖性能,并能为奶牛场节省成本,提高经济效益。

Methods to Evaluate Rumen Protected Lysine for Dairy Cows

There are many rumen protected amino acid products available for dairy cattle feeding. However, feed formulation programs require values related to rumen solubility, rate of disappearance in the rumen and total tract digestibility and often such values are not available. In vivo testing procedures are complex, time consuming and expensive. This study was conducted to determine if a newrapid, lower cost in vitro method developed for feed ingredients could be applied to a rumen protected lysine product (DairynatLys-30, Jefo Nutrition Inc). In vivo determination of the rapidly solubilized protein fraction, rate of degradation of the slowly solubilized fraction and total tract digestibility studies were compared to the in vitro method in use in many ingredient analysis laboratories for feed ingredients such as forages, protein supplements and grains. Results showed that the rapidly soluble fraction (8.33% and 8.66% of total N for in vivo and in vitro methods) and rates of disappearance in the rumen (2.64%/h and 2.43%/h for in vivo and in vitro procedures) compared favorably between the two methods for the rumen protected product. Total tract digestibility values were slightly higher (84.4%) with the in vivo method used than with the in vitro method (75.9%), and both are in the expected calculated range of digestibility of 80%. In conclusion the in vitro method appears to be an acceptable alternative for evaluating rumen protected amino acids.