Characterization and comparison of growth curves in slick and wild type-haired Puerto Rican Holstein calves and heifers

Abstract

The ideal weight gain for Holstein heifers in the United States is between 0.73 and 0.86 kg/d. However, heat stress may limit growth, whereas a slick-haired coat confers superior thermoregulation. This study compared and evaluated (GLIMMIX and REG Procedures-SAS) body weight, hip height, shoulder to pin bone distance, thoracic perimeter, withers height, and barrel growth curves of nine slick vs. nine wild type-haired Holstein calves, weekly [one to eight weeks of age (1 to 8 WOA)] and monthly [three to 33 months of age (3 to 33 MOA)]. From 1 to 8 WOA, no hair coat type x age interactions (P≥0.1834) or hair coat type effects (P≥0.4778) were observed. During this period all variables evaluated increased linearly (R2≥0.34; P<0.0001). From 3 to 33 MOA, only body weight (P=0.0312) and barrel circumference (P=0.0038) presented a hair coat type x age interaction. No hair coat type effects (P≥0.5398) were observed. During this period, all dimensions demarcated by bones behaved quadratically (R2≥0.87; P<0.0001), while body weight remained linear (R2≥0.94; P<0.0001). From 1 to 8 WOA, gains of 0.48 and 0.48 kg/d were observed in slick and wild type-haired calves. Respective gains of 0.61 and 0.62 kg/d were noted in heifers 3 to 33 MOA. No growth-related differences were observed between hair coat types. Limited gains were observed in both groups.