Effect of colostrum volume at birth on growth, live carcass ultrasound, and feed efficiency in Holstein and Holstein-Angus steers.

Abstract

Dairy-beef calves represent a growing proportion of the beef supply, yet little is known about how early-life nutrition affects long-term performance. This study evaluated the effects of breed and colostrum replacer (CR) volume at birth on growth, feed intake, feed efficiency, and carcass-related traits in Holstein and Holstein-Angus calves from birth to slaughter at 13 mo of age. Male Holstein (n = 20) and Holstein-Angus calves (n = 20) were enrolled at birth and assigned to receive either 2.5 or 5.0 g of IgG/kg of birth BW from CR (n = 10 per breed and CR treatment), divided into equal meals at 0 and 12 h after birth. Thereafter, calves were managed similarly and fed the same diets until slaughter. Individual intake was recorded daily, whereas BW, frame measurements, and live carcass ultrasound traits were collected monthly. Apparent total-tract digestibility was estimated at wk 28 and 55, and ruminal VFA concentrations were measured at wk 28 and 48. Data were analyzed using linear mixed models for repeated measures, and a nonlinear mixed model was used to fit a growth function to cumulative intake. Breed was the primary factor affecting performance across the rearing, growing, and finishing phases. Holstein-Angus steers grew faster, consumed more feed, and had greater feed efficiency at a common BW than Holstein steers. At wk 48, fiber digestibility and acetate-to-propionate ratio were greater in Holstein steers. Holstein-Angus steers also had greater ribeye area and greater rump and rib fat thickness during the growing and finishing phases. Colostrum replacer volume had limited effects on most growth and intake outcomes; however, steers receiving the high CR volume had greater rump and rib fat thickness during the growing and finishing phases, suggesting that early-life nutrition may influence later body composition. Holstein steers receiving the low CR volume had a lower predicted final BW and required greater DMI to reach 650 kg BW, as estimated using the Richards function, whereas Holstein-Angus steers were not affected. These findings emphasize the dominant role of breed in lifetime performance while indicating that colostrum volume fed at birth may have long-term effects on intake and adipose tissue deposition.