Feeding rumen-protected choline (RPC) to late gestation dairy cows has potential to affect growth in offspring. The objective of this study was to evaluate the effects of in utero choline exposure on the growth, feed efficiency (FE), metabolism, and carcass quality of Angus × Holstein cattle. Multiparous Holstein cows pregnant with male (N = 17) or female (N = 30) Angus-sired calves were enrolled 21 d prepartum and randomly assigned to one of four dietary treatments varying in quantity and formulation of RPC. The treatments included a control with 0 g/d supplemental RPC (CTL), supplemental RPC fed at the recommended dose (RD) of 15 g/d from either an established RPC product (RPC1RD; ReaShure; Balchem Corp.) or choline ion from a concentrated RPC prototype (RPC2RD; Balchem Corp.), or a high dose (HD) of RPC2 fed at 22 g/d (RPC2HD). From 2 to 6 mo of age, calves were group housed and offered 2.3 kg grain/hd/d (42% CP) with ad libitum grass hay, and stepped up to a complete finishing diet by 7 mo (12.0% CP; 1.34 Mcal/kg NEg). Weight and height were measured monthly. Animal FE was measured in individual pens for 35 d at 8 mo. Feed intake was measured daily, and blood was obtained on day 18 during the FE period. Afterwards, cattle were group housed and offered a free-choice finishing diet until slaughter, where carcass yield and quality characteristics were measured. Mixed models were used in PROC MIXED (SAS, 9.4) with the fixed effects of treatment, sex, time, their interactions, and the random effect of calf. Month was the repeated measure, and preplanned contrasts were used. Blood and FE data were analyzed with the fixed effect of dam choline treatment, calf sex, and the interaction. Increasing dose of RPC tended to increase weight over the entire study period. Feeding any RPC increased hip and wither height compared with CTL, and increasing RPC dose linearly increased hip and wither height. Treatment and sex interacted on DMI whereby increasing RPC intake linearly increased DMI for males but not females. Compared with control, feeding any RPC decreased plasma insulin, glucose, and an insulin sensitivity index (RQUICKI). In utero choline exposure increased kidney-pelvic-heart fat and marbling score. Mechanisms of action for intrauterine choline exposure on offspring growth, metabolism, and carcass characteristics should be explored as they have direct implications for profitability for cattle growers and feeders.
Keywords: beef; carcass characteristics; developmental programming; feed conversion.
Common nutritional and management programs implemented during gestation in dairy cattle also have positive outcomes for offspring growth, health, and well-being. Recent work has demonstrated that supplementing rumen-protected choline (RPC) to dairy cows for several weeks before calving increases growth and feed efficiency (FE) of their calves. Considering the recent industry trends of breeding dairy cows with beef semen, any potential growth and FE advantages imparted by prenatal RPC supplementation of the dams could help increase value of the resulting beef × dairy calves. The objective of this study was to evaluate growth, FE, and carcass characteristics of beef × dairy calves from dairy cows supplemented with RPC before calving. Feeding RPC to dairy cows before calving increased offspring weight and height through 9 mo of age. In utero exposure to choline also improved markers of insulin sensitivity of the offspring while being fed with a high-energy diet. Dam dietary RPC supplementation increased offspring kidney, pelvic, and heart fat at slaughter, and also increased marbling score. Considering the importance of marbling in carcass quality, the potential of RPC to positively influence offspring performance could be beneficial for further enhancing value of beef × dairy cattle at slaughter.
© The Author(s) 2023. Published by Oxford University Press on behalf of the American Society of Animal Science.