Adsa Logo White Adsa Title White

The effects of nutritional management in early lactation and dairy cow genotype on milk production and metabolic status.

E. L. Brady

Events

06-24-2020

Abstract:

313
The effects of nutritional management in early lactation and dairy cow genotype on milk production and metabolic status.
E. L. Brady*1, M. B. Lynch2, K. M. Pierce2, A. G. Fahey2, F. J. Mulligan1. 1School of Veterinary Medicine, University College Dublin Belfield, Dublin, Ireland, 2School of Agriculture and Food Science, University College Dublin Belfield, Dublin, Ireland.

High levels of milk production coupled with low feed intake causes negative energy balance in early lactation, especially in the first month post calving. Therefore, specific nutritional management at this time may improve nutritional and metabolic status with the possibility of genotypes responding differently. Thus, the objective of this study was to compare the effects of contrasting nutritional management strategies and dairy cow genotypes on milk production and metabolic status during early lactation for grazing cows. Sixty Holstein-Friesian cows were blocked on calving date, previous 305 d milk yield, BCS and genotype. Cows of high fertility low milk (HFLM) and low fertility high milk (LFHM) genotype (based on the 2019 Economic Breeding Index evaluation, ICBF Ireland) were randomly assigned to 1 of 2 treatments in a 2 � 2 factorial, randomized complete block design. The dietary treatments were: 1) allocation of 21kg of DM of a tailored TMR (TMR, n = 30); 2) ad libitum access to fresh pasture plus an allowance of 3 kgs of concentrates (G, n = 30). These diets were offered for the first 30 DIM. Post 30 DIM, TMR cows joined the G treatment and were managed similarly until 100 DIM. Blood samples were taken weekly in the first month after calving and BCS recorded every 2 weeks. BCS and BCS loss were analyzed using PROC MIXED of SAS (9.4 2012) and blood metabolites using repeated measure MIXED procedure of SAS (9.4 2012). Feeding TMR for the first 30 DIM significantly improved the metabolic status as NEFA (−0.12 mmol/L, P < 0.001) and BHB (−0.10 mmol/L, P < 0.001) were lower compared with the G treatment. Overall, BCS was higher for TMR (2.91) compared with G (2.86, P = 0.03) cows. Cows of LFHM had an increased BCS when fed TMR (P = 0.04), presenting a NM X genotype interaction. Additionally, TMR cows had a lower BCS loss (−0.23) from calving until 60 DIM compared with G cows (−0.41, P < 0.01). Genotype did not have an influence on metabolic status. In conclusion, specific NM in the first month after calving improves metabolic status and significantly reduces BCS loss up to 60 DIM regardless of genotype.

Keywords: early lactation, nutritional management, genotype.