Estratégias de suplementação para vacas e para novilhas de corte dos quatro aos dezoito meses de idade

• Autor(a) principal: Couto, Victor Rezende Moreira
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1795
• topic: Bovinos; Fêmeas; Suplementação; Cattle; Females; Supplementation; CNPQ::CIENCIAS AGRARIAS::ZOOTECNIA::NUTRICAO E ALIMENTACAO ANIMAL

Three experiments were conducted to evaluate supplementation strategies for cows and beef heifers from four to eighteen months old. The first experiment was carried out to evaluate the performance, forage intake, total dry matter intake, and digestibility. Forty-one crossbred calves (at least 50% Nellore cross), with initial shrunk BW of 131±5 kg and initial age of 120 day were used. The animals were supplemented with different amounts of multiple supplements, grazing Brachiaria decumbens Stapf, until 18 mo old. The animals were randomly assigned to one of five strategies supplementation: only mineral mixture (control), low level, medium-low level, medium-high level, and high level of supplement intake. The experiment was split into four experimental stages, including transition rainy-dry, dry, transition dry-rainy, and rainy season. Overall, the inclusion of multiple supplements up to medium-high level did not decrease the forage intake compared to the control treatment. However, there was a decrease in forage intake in the group treated with the high inclusion of multiple supplements. This intake was 20.3% lower compared to the mediumhigh treated group (3.194 kg/day versus 3.842 kg/day). The average forage dry matter intake was 16.386, 15.464, 15.220, 16.373, and 12.892 g/kg of BW for control, low, medium-low, medium-high, and high groups, respectively. The total dry matter intake was greater for the medium-high and high levels of supplementation (average during full experimental period of 21.062 and 17.447 g/kg of BW for high and control groups, respectively). At the end of the second experimental stage (dry season), there was a greater final BW in the high group than in the control group, whereas during the full experimental period this difference was observed only in the medium-high group compared to the controls. The final BW was 261.4, 276.5, 290.8, 293.4, and 330.4 kg for the control, low, medium-low, medium-high, and high level of supplementation, respectively. At the end period of dry-rainy transition, the average BW was 286.4 kg for the high group (63.3% of the weight of adult cow of 450 kg). The animals submitted at the medium level reached this condition only at the end rainy season, around 18 mo old. The weight gain of Nellore or crossbred heifers supplemented and grazing Brachiaria decumbens Stapf, increases with the inclusion of multiple supplements at diet. The use of multiples supplements increased the dry matter intake of beef heifers. The digestibility s of organic matter and crude protein increased with supplementation levels. The digestibility of neutral detergent fiber corrected for residual ash and protein were not affected by the concentrate inclusion. In the second experiment the objective was to evaluate the milk production, the change in BW and body condition score (BCS), like the forage intake and digestibility of dietary components ingested by lactating Nellore or crossbred, with zebu blood predominance, handling under creep-feeding system grazing Brachiaria decumbens Stapf, from four to eight months of lactation. Forty-one cows were used and their respectively offspring. Each set (matrix and calf) was randomly one of five supplementation strategies of energy-protein supplement and mineral to be supplied to the calves, as follows: T0 - (no supplementation - receiving only mineral mixture ad libitum); T250 - (0.250 kg/animal ) T500 - (0.500 kg/animal), T750 - (0.750 kg/animal) and T1000 - (1.000 kg/animal). To evaluate the forage intake and digestibility was conducted a test for 10 days, the first of seven days for the adaptation of animals to chromium oxide indicator, which was used to estimate the fecal excretion. The forage DM intake, as well as other dietary components was not affected by treatments. The average forage DM intake by cows was 10.171 kg/day or 22.734 g /kg of BW. No differences were observed on TDN intake by cows with increasing concentrate supply to the offspring. The average TDN in the diet of the cows was 465.20g of TDN /kg of DM. The organic matter digestibility was observed on average 50.29% and was not influenced by treatments, as well as CP and NDF digestibility, which were 36.54% and 59.43% respectively. A quadratic effect was observed under the variation of BW gain with a maximum gain of cows when the calves are supplemented with 0.598 kg of concentrate. However, the quadratic regression equation was tested for the lack of fit, are not provided adequate to explain the weight variation of the cows from the use of multiple supplement add-on of their offspring. There was an increase in BW, on average 13.8 kg for the cows suckling supplemented calf, to the control treatment, this variation was only 1.9 kg throughout the experimental period. The fact of provide concentrate supplement to calves, eventually may reduce the dependence of these animals in relation to their mothers with regard to obtaining food. There was a linear decrease in milk intake as it provided the concentrate to calves (P<0.02). The supplemented calves consumed on average 3.76 kg of milk/day while non-supplemented calves consumed 5.45 kg per day. It was observed by adjusting the regression equation for each kg of supplement provided to offspring, 2.088 kg of milk was no longer consumed by these calves. The DM intake of cows suckling calves on creep-feeding system does not differ from cows suckling calves not supplemented and was on average 10.257 kg/day, or 22.928 g/kg of BW. The inclusion of multiple supplements in the diet of suckling calves results in lower milk production by the matrix. In addition, there is an increase in weight of cow when the calf is suckling on creep-feeding system. The third experiment was carried out to evaluate the body condition score (BCS), forage intake, and digestibility of the nutrients ingested by Zebu cows in the final third of gestation, supplemented with different amounts of multiple supplements, grazing Brachiaria decumbens Stapf, during dry season. Fifty two multiparous pregnant cows with zebu blood predominance were used. Each animal was randomly assigned one of five levels of supplementation. The treatments were: Control (receiving only mineral mixture ad libitum), T400 (0.400 kg/animal), T800 (0.800 kg/animal), T1200 (1.200 kg/animal) and T1600 (1.600 kg/animal). The multiple supplement was formulated to contain 28% CP. The animals were weighted at the beginning and end of the experiment. The change in BCS was determined by the difference between the initial and final BCS, a score scale 1-9 was used. To evaluate the intake and digestibility of diet ingested was held early in the second period, a trial lasting 10 days, seven for the adaptation of animals to external indicators chromium oxide and titanium dioxide. The chromium oxide was used to estimate the fecal excretion and the titanium dioxide was mixed to the supplement immediately prior to delivery, to enable the measurement of the individual intake of the supplement. The addition of the supplement to the level of 1.600 kg/day showed positive linear correlation with most consumer variables studied, increasing the DM intake, organic matter intake, CP intake, NDF intake, nonfibrous carbohydrates intake, and as increasing of the dietary components digestibility, resulting in an increase in TDN intake and also increase of the TDN concentration in the diet of animals. The forage DM intake and NDF intake in relation to BW showed a quadratic behavior in relation to supplement intake, with lower forage intake on the level of supplementation estimated 0.667 kg/animal and NDF for the estimated level of 0.450 kg/ animal. The average forage DM intake was 14.255 g/kg of BW. These results are consistent with the low quality and availability of forage grazed. The change in BW of cows also showed a linear response to the inclusion of multiple supplements. The immediate implication of this observation is the ability of supplementation to increase the matrix body condition score during the final third of gestation. The change in BCS assessed 30 days after supplementation period was linearly increased with the inclusion of concentrate in the diet of animals. The microbial protein synthesis was not affected by the treatments on a regular basis. The BCS increases with the addition of concentrate in the diet, even when measured after supplementation in the postpartum period. By providing multiple supplements, to cows grazing Brachiaria decumbens Stapf, during the dry season, in the final third of gestation the DM intake is increased, as well as the digestibility of the diet components.