Early-life Nutritional Programming of Growth, Metabolism, and Carcass Traits in Dairy-Beef Steers

Early-life nutrition may influence long-term growth, metabolism, and tissue development, yet these relationships remain poorly characterized in cattle raised for beef. Studies were conducted to determine how early-life nutritional strategies shape lifetime performance, metabolic development, and carcass outcomes in dairy-beef steers. In the first study, 20 Holstein and 20 Holstein-Angus male calves received either a low or high volume of colostrum replacer at birth and were followed under common management to slaughter at 13 months. Growth, intake, feed efficiency, frame development, live carcass ultrasound, circulating amino acids, metabolites and hormones, carcass traits, and meat composition were evaluated. Breed was the primary determinant of lifetime performance. Holstein-Angus steers grew faster, consumed more feed, were more feed efficient at an equivalent body weight, and developed greater muscle and fat than Holsteins. These differences resulted in heavier carcasses with greater intramuscular fat and a more saturated fatty acid profile, whereas tenderness and most meat colour traits were similar between breeds. Circulating profiles changed predominantly with developmental stage, with major shifts during neonatal adaptation, weaning, and feedlot maturation; breed-related metabolic divergence emerged mainly after weaning. Increasing colostrum replacer volume improved early nutritional status and increased subcutaneous fat deposition during the feedlot phase, but had limited effects on lifetime growth, carcass merit, and meat quality. In the second study, 68 dairy-beef calves were assigned in a 2 × 2 factorial arrangement to high-lactose or high-fat milk replacer and control or palmitic acid-supplemented solid feed. Growth, intake, ultrasound and carcass traits were measured to slaughter, and glucose-insulin dynamics were evaluated longitudinally in 33 steers. High-fat milk replacer increased milk intake shortly after arrival but did not improve long-term growth, whereas high-lactose milk replacer increased finishing-phase fat deposition. Palmitic acid supplementation transiently reduced intake and growth, altered glucose-insulin dynamics, and increased kidney, pelvic, and heart fat without affecting slaughter body weight. With age, insulin responses increased while insulin sensitivity and second-phase pancreatic responsiveness declined. In summary, breed and develop-mental stage were the predominant drivers of dairy-beef growth, metabolism, and carcass development, while early-life nutrition exerted selective, persistent, and depot-specific effects on adipose tissue accretion.