Growth, puberty, and carcass characteristics of Brahman-, Senepol-, and Tuli-sired F-1 Angus bulls

Postweaning growth, sexual development, libido, and carcass data were colle cted from two consecutive calf crops using 31 Brahman x Angus (B x A), 41 S enepol x Angus (S x A), and 38 Tuli x Angus (T x A) F-1 bulls. Following we aning (by mid-September) and preconditioning, at the start of the study (la te September) bulls were fed concentrate (three times each week at a rate e quivalent to 4.5 kg/d) on bahiagrass pasture for approximately 250 d. At th e start of the study and at 28-d intervals, BW, hip height, and scrotal cir cumference (SC) were measured. Concurrently at 28-d intervals, when the SC of a bull was greater than or equal to 23 cm, semen collection was attempte d using electroejaculation. Ejaculates were evaluated for presence of first spermatozoa (FS), 50 x 10(6) sperm with at least 10% motility (PU), and 50 0 x 10(6) sperm with at least 50% motility (PP). After all bulls reached PP they were subjected to two libido tests. Carcass data were collected on al l bulls (n = 110) and Warner-Bratzler shear (WBS) force values were assesse d on a subset (n = 80). For both years, B x A bulls were heavier (P < 0.05) and taller (P < 0.05) than S x A and T x A bulls at the start and end of t he study. However, breed type did not influence (P > 0.10) gain in BW or hi p height during the study. Scrotal circumference of T x A bulls was larger (P < 0.05) than that of B x A or S x A bulls at the start of the study, but there was no effect (P > 0.10) of breed type by the end of the study. At P U and PP, B x A bulls were older (P < 0.05), heavier (P < 0.05), and taller (P < 0.05) and had larger (P < 0.05) SC than S x A and T x A bulls. Tuli x Angus bulls were younger (P < 0.05) than S x A bulls at PU and PP but had similar SC. Libido scores tended (P < 0.10) to be lower for B x A than for S x A and T x A bulls. Breed type affected (P < 0.05) carcass traits; B x A bulls had the heaviest (P < 0.05) hot carcass weight, greatest (P < 0.05) dressing percentage, larger (P < 0.05) longissimus muscle area than S x A b ulls, and higher (P < 0.05) USDA yield grade than T x A bulls but greatest (P < 0.05) WBS force values. Breed type did not affect (P > 0.10) USDA qual ity grade. In conclusion, tropically adapted F-1 bulls produced from Senepo l (Bos taurus) and Tuli (Sanga) sires bred to Angus cows in Florida had lig hter BW, shorter hip heights, and smaller carcasses than those from Brahman sires but reached puberty earlier and had higher libido scores and lower W BS force values.