Impacto de las vitaminas B protegidas en el rendimiento de novillas durante el destete y hasta la primera lactancia.

INTRODUCTION

The objective of
this study is to evaluate the effects of supplementation with protected B
vitamins (vitamins B1, B5, B6, B9 and B8) on the growth of calves during the
weaning period and the ability of heifers to reach their first calving and
their milk production (up to 97 days of lactation). The trial was conducted on a dairy farm with 950 Holstein cows with an average milk production of 11,800 kg/cow/year. All female calves (n=80) born during the test period (December and January) were involved in the trial. The calves were allocated according to their date of birth in order to divide the animals into 4 consecutive batches of 20 calves each (15d old between each batch). Two batches were fed a diet supplemented with B vitamins (the 1st and 3rd chronologically) and the other two batches remained on the basal feed (control). The calves followed a milk feeding plan with 2×3 L per day from D5 to D67 and then 2×1.5 L from D68 to D75 (170 g/L of milk replacer). They were gradually weaned and given solid feed ad libitum as per Table 1. The calves were weaned on the 75th day of their lives. The B vitamin mixture was incorporated into the mash feed for 3 weeks before weaning and in the total mixed diet for 3 weeks after weaning (the supplementation lasted 6 weeks). The B vitamin mixture was included in the diet to provide 3 g/calf/day at weaning. Body weight (BW) was recorded at the beginning (53d) and at the end of the test (96d). The calves in each group were born at 2 weeks of age from each other and their mean age at trial start was 53 days (SD = 4.9). Initial BW (3 weeks before weaning) varied in the same way as the calves’ age (75 kg, SD = 8.6).

Table
1: Composition of the solid diet

The overall body
gain was calculated by subtracting the initial BW from the final BW. Average
daily gain (ADG) was calculated by dividing overall body gain by the total
number of days (41 to 42 days). Data were analyzed using the Proc Mixed
procedure (SAS v. 9.4) using batch (1, 2, 3, 4) as a fixed effect. Orthogonal
contrasts (batch 1+3 vs. 2+4) were used to assess the effect of B vitamins. Initial
BW was used as a covariate in the analysis of final BW and ADG to account for
differences in initial BW (average adjustment).

The weaned calves remained on the same farm and were managed as a single group of replacement heifers according to farm standards (with a TMR without B vitamins). Our second objective was to assess the residual effect of the previous treatment on heifers’ ability to reach their first calving and milk production (up to 97 days of lactation). Culling data were analyzed using the Chi 2 assay and milk data were analyzed using ANOVA with repeated measurements using SAS Studio.

Results

Calves receiving B vitamins gained 8.5 ± 1.4 kg more than the control calves during the trial period (final body weight respectively, 116kg vs 107,5kg, p < 0,001). Calves receiving B vitamins gained 178 ± 0.3 g/day more than the control calves during the same period (p < 0,001). The final body weights of the calves receiving B vitamins were higher than those of the control group.

90% of heifers
receiving B vitamins during weaning reached first lactation and 75% of heifers
from the control group (p = 0.078). During 3 first milk control, heifers
receiving B vitamins produced 36,9kg/d and control heifers produced 35,1kg/d, without
significant difference (p = 0.12).

DISCUSSION

Recent work has
shown that the quantities of B vitamins synthesized in the rumen are not
sufficient to cover the needs of high-production animals (Girard et al.,
2005, Santschi et al., 2005). As a high proportion of the B vitamins
provided by feed are degraded by the rumen microflora, providing them in a
protected form allows a low rumen degradation and intestinal release of these
vitamins. During weaning period, we can speculate that B vitamins supply from
rumen fermentation are not sufficient to cover the high needs of the
metabolism.

The trial was
conducted during winter, with the four groups allocated within 2 months. The
environmental effect is expected to have limited impact on the results.

conclusion

In this trial
conditions with its limits, calves that received the rumen-protected B vitamin
mix during the weaning period gained 8.5 kg more than control calves. In
addition, the follow-up study showed that these weaned heifers seem to have a
better chance of reaching their first lactation.

This innovative
nutritional solution has the potential to improve calf performance during the
stressful weaning period and support the heifer’s future career. This
observation needs to be confirmed with a large number of animals.

 Girard C.L., Lapierre H., Matte J.J.,
Lobley G.E., 2005. J. Dairy Sci. 88 : 660-670

Santschi D.E., Berthiaume R., Matte J.J., Mustafa A.F.,
Girard C.L., 2005. J. Dairy Sci. 88 : 2043