Resumen de Efecto de la suplementación de grasas sobre características productivas, tasas de preñez y algunos metabolitos de los lípidos en vacas para carne en pastoreo.
José Luis Espinoza Villavicencio, Ricardo Ortega Pérez, Alejandro Palacios Espinosa, Ariel Guillén Trujillo
In order to evaluate the effect of a supplementation with two sources of fat in beef cows on range, 120 adult females in two herds were used. One herd of 60 Charolais cows (A) and another herd of 60 Chinampo cows (B, local Creole) were fed (2 kglcow/day) isoproteic concentrates (PC = 16.6%) with a similar content ofME (aprox. 3.0 Mcal/kg) during a 90 days period (initiating 30 days precalving), respectively. In each herd, cows were randomly assigned into three groups. The control groups (TE; n = 20) were fed a supplement containing 3.2% of fat. Another group of 20 cows per herd was fed a supp1ement containing additional fat (13.2%) as ca1cium soaps offatty acids (JCAG). The third group (SB) within each herd (n = 20) was fed a supplement containing 13.4% of fat (bovine tallow). Orthogonal contrasts (TE vs SB + JCAG and SB vs JCAG) were used to compare the means of non categorical variables. In herd A, mi1k yield was greater at 35 (P < 0.05) and 90 (P < 0.01) days of lactation in cows fed supp1emental fat (SB + JCAG) Iban TE treatment. In both herds, weight of ca1ves at 35 and 90 days of age, body weight and body condition score of cows at 90 days postca1ving were higher in SB + JCAG than TE (P < 0.01). Serum cho1esterol, high density 1ipoproteins, low density 1ipoproteins and triglycerides were greater in cows supplemented with fat (SB + JCAG) than TE treatment (P < 0.01). Pregnancy rates in both herds were higher in fat supplemented cows (P < 0.05). We concluded that additional fat incorporated in a range supp1ement during pre and postpartum periods increased milk yie1d, growth of calves, body weight and condition score of cows, lipid metabolites and pregnancy rates.
