EVALUACIÓN DE LA VITAMINA D3 SOBRE EL COMPORTAMIENTO ANIMAL, CARACTERÍSCTICAS DE LA CANAL Y TERNEZA DE LA CARNE DEL GANADO BRAHMAN Y SUS CRUCES. GUALACA, PANAMÁ. 2003.

The purpose was to evaluate the effect of vitamin D3, on the animal performance (AP), carcass traits (CT) and beef tenderness (TRN) of Brahman and its crosses. Two fattening (A) were done: (110 days) and A2 (133 days) with two racial groups (GR): Brahman (Br) y Crossbred (Cx). Levels of vitamin D3 (T) were: 0 (T1), 2.5 (T2), 5.0 (T3) y 7.5 (T4) x 106 UI/animal/d, supplied 10 days before finished fattening period. Samples of the Longissimus dorsi were taken from the 11th and 12th rib from both carcass sides. Performance traits were: initial weight (PI), final weight (PF), daily weigth gain  (GDP), last month weight (PUM) y daily weight gain at last month (GDPUM); from the carcass: slaughter weight (PM), hot carcass weight (PCC), dressing percentage (RC), carcass length (LC), proportion of pelvic fat (PGP) and USDA yield grade (YG); from the beef (Longissimus dorsi): rib eye area (AL), fat thickness (GD), bone proportion (HP), beef proportion (MP), fat proportion (GP) and tenderness (TRN), measure at four aging time (TM): 7, 14, 21 and 28 days postmortem. Dependent variables were analyzed by a generalized linear model using PI as covariable. PI was effective (P<0.10 a P<0.01) for PF, PM, PUM, PCC, AL, MP and GP. As blocking criteria (A) was significant (P<0.05 a P<0.01) for PF, GDP, PM, PUM, GDPUM, PCC, LC, PGP, AL and TRN. Besides, T only affected negatively to PUM y GDPUM (P<0.01), but while level of vitamin D3 increased, TRN value decreased to 18.8% (T4 vs T1). Cx overcame (P<0.01) in 29.0% and 14.7% to Br in YG and AL, respectively. T*GR was significant (P<0.10 a P<0.01) in PF, GDP, PUM, LC, YG, GD, AL and TRN. TM improved (P<0.05) TRN as days increased (21.2% between day 7th and day 28th). T*TM resulted significant (P<0.05). lt was concluded that vitamin D3  and aging  time have great effects on TRN, but little on AP and CT.