Estratégias de suplementação para fêmeas bovinas de corte em diferentes fases do ciclo produtivo

• Autor(a) principal: Barros, Lívia Vieira de
• Data de Publicação: 2012
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1818
• topic: Fêmeas; Bovinos; Suplementação; Beef; Heifers; Supplementation; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

This thesis was drawn from three experiments with beef heifers under different supplementation strategies at pasture. The first work aimed to evaluate productive and nutritional performance of female calves fed mineral mixture or multiple supplements and milk production, pasture intake and digestibility of beef cows, in Uruchloa decumbens pastures. It was used 48 female calves with average age of 5 months and initial average weight of 125.4±1.34 kg and their respective dams with initial average weight of 435.2 ± 10.3. The experimental design was the complete random design. Supplements contained approximately 25% of crude protein (CP) and progressive replacement of soybean meal (SB) by cotton seed meal 38% (CS) at the levels of 0; 33; 67 and 100% for treatments CS0, CS33, CS67 and CS100, respectively. Animals in the control treatment (CT) were fed only mineral mixture ad libitum; supplements were offered at the amount of 0.5 kg/animal/day in the other treatments. Daily gain (g) was 687.8; 733.2; 820.0; 760.6, respectively for treatments CT, CS0, CS33, CS67 and CS100. Supplemented female calves presented greater weight gain. It was not found effects of the levels of CS (P>0.10) on daily average gain. Intakes in kg/day of dry matter (DM), organic matter (OM), crude protein (CD), non fibrous carbohydrates (NFC), digested dry matter and total digestible nutrients were greater (P<0.10) for supplemented animals than for non supplemented animals. It was found a linear decreasing effect among levels of replacing SM by CS with the increasing level of CS on intake of digested dry matter and digested neutral detergent fiber. Coefficients of total apparent digestibility of DM, OM, CP and NFC were the highest (P<0.10) for supplemented animals. A decreasing linear effect on digestibility of neutral detergent fiber was found among replacing levels of SM by CS. Supplementation of female calves did not influence the performance of the cows, the milk production and dietary components by the cows (P>0.10). It is concluded that supplementation in the pre-weaning period provides a greater weight of female calves. The second work aimed to evaluate the effect of supplementation with multiple supplement or mineral mixture in the dry season (phase 1) and/or dry-rainy transition season (phase 2) on the nutritional variables and productive performance of beef cattle in Uruchloa decumbens pasture. It was used 40 40 x heifers at initial age and average weight of 8 months and 200 ± 3.74 kg, respectively in a complete random design with four treatments and 10 replicates. In the phase 1, two groups of animals were fed multiple supplement and the other two groups were fed only mineral mixture ad libitum. In the second phase of the experiment, the two groups that received multiple supplements, one continued to receive multiple supplements and the other was receiving only mineral. For the two groups fed only mineral mixture in the phase 1, one continued receiving mineral mixture in phase 2 and the other receiving supplement in phase 2. In the phase 1, supplemented animals presented greater average daily gain (ADG), the supplementation increased intake in kg/day of dry matter (DM), organic matter (OM), CP, non fibrous carbohydrates (NFC), digested dry matter (DDM), and total digestible nutrients (TDN) and it improved digestibility of all dietary constituents (P<0.10), except neutral detergent fiber (NDFap) and ether extract (EE) (P<0.10). The supplementation in the dry-rainy transition season (phase 2) increased intake in kg/day of DM, forage dry matter (FDM), OM, forage organic matter (FOM), CP, EE, DDM, digested neutral detergent fiber (DNDF) and indigestible neutral detergent fiber. There was an interaction effect on supplementation in the dry season and in the dry-rainy transition season on the ADG, NFC intake, on the coefficients of DM, OM, CP, NDFap and on the content of TDN. It is recommended the use of multiple supplements for grazing beef heifers in the growth phase in the dry season and in the rainy-dry transition period. Supplementation in the dry season improves performance of supplemented animals in the rainy-dry transition season. The third work aimed to evaluate the effect of multiple supplements with different levels of crude protein on nutritional parameters, efficiency of microbial synthesis and performance of beef heifers grazing Uruchloa decumbens in the rainy season. Thirty-nine heifers at 14 months of age and body weight of 229.3 ± 0.7 kg were used in the experiment. The experimental design was the complete random design. The treatments were increasing levels of crude protein in the supplements and a control treatment (MM) in which animals were offered only mineral mixture. The supplements contained 17; 30; 43 and 56% of crude protein (CP), for treatments CP17; CP30; CP43 and CP56, respectively. Average daily gain (ADG) (g) was 447.7; 554.6; 638.4; 587.9; 590.4, for treatments MM, CP17; CP30; CP43 and CP56, respectively. It was found a quadratic effect of the levels of crude protein (P<0.10) on ADG. A greater intake of dry matter (DM), organic matter (OM), CP, ether extract (EE), non-fibrous carbohydrates (NFC), total digestible nutrients (TDN), and digested dry matter (P<0.10) was found for supplemented animals. A reduction in the forage DM intake with a raise in the level of CP in the supplement was found among levels of crude protein in the supplements. Supplementation increased the apparent digestibility coefficient of DM, CP, EE and NFC. A quadratic effect in the level of crude protein in the supplements was found on the digestibility of DM, EE, OM, neutral detergent fiber, NFC and for the content of TDN. Efficiency of microbial protein synthesis (EFIM) did not differ among supplement and non-supplemented animals. Level of CP in the supplement had a linear positive effect on EFIM. The supply of multiple supplements for heifers grazing medium to high quality pastures in the rainy season improves performance of the animals. The supply of supplements with high levels of CP in the rainy season decreases forage intake.