Ração concentrada à base dos farelos de soja ou de algodão em dietas contendo silagem de milho para fêmeas leiteiras em crescimento / Concentrate ration based on soybean or cottonseed meal in diets containing corn silage for dairy females

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The objective of this work was to evaluate concentrate rations based on soybean or cottonseed meal in diets containing corn silage to dairy females, on intake and total apparent digestibility of nutrients, performance, ingestive behavior, diets economic viability, nitrogen balance (NB) and microbial protein production.. There were used 28 crossbred heifers, with approximately 10 months mean age and 180 kg initial mean weight, distributed in a randomized blocks design, with seven repetitions. The four experimental treatments were constituted by the combination of two levels of concentrate ration, one or two kilos, and two protein sources, soybean meal or cottonseed meal, in a 2 x 2 factorial scheme, in isonitrogen diets with corn silage as roughage. There was effect of the interaction between the factors (P<0.05) to dry matter (DM) intake in g/day and live weight %, to neutral detergent fiber (NDF) intake in live weight % and to total digestible nutrients (TDN) intake in kg/day, in which the animals that consumed 1 kg of concentrate ration showed smaller DM and TDN intakes, and the ones that consumed 1 kg of soybean meal showed smaller NDF LW% intake. There was effect of concentrate quantity (P<0.05) on crude protein (CP), NDF, ether extract (EE), non fiber carbohydrates (NFC), organic matter (OM) and g CP/kg TDN intakes, in which the animals that consumed 2 kg of concentrate ration showed greater intakes. There was no significant effect of the factors on DM, NDF and OM digestibilities and on observed TDN, however, there was protein source effect (P<0.05) on CP, EE and NFC digestibilities, in which the diets based on soybean meal showed greater digestibility. There was no significant difference of the estimates of fecal DM excretion and DM, OM, CP, NDF, EE and TDN digestibility coefficients estimated by the internal markers NDFi or ADFi (P>0.05), however, the NFC digestibility coefficient was greater when estimated by ADFi. There was no significant effect of no one of the factors on rumination, feeding and idle time in hours, DM and NDF feeding and rumination efficiency in kg/h, number of ruminating chewing/day, number of ruminating bolus/day, number of ruminating chewing/bolus, total chewing time/day and bolus ruminating time. It was not observed effect of concentrate quantity on the variables weight gain in kg/day and live weight %. For weight gain per cm of withers height gain (WG/cm WH) there was effect of interaction between the factors (P<0.05), in which the treatment that received 2 kg of concentrate ration based on soybean meal provided the smaller weight gain by this ratio. There was effect of concentrate quantity on thoracic perimeter, croup width and weight with measuring tape parameters (P<0.05), in which the heifers that consumed 2 kg of concentrate ration obtained greater growth. However, there was interaction effect on croup height and withers height, in which the animals that consumed 1 kg of concentrate ration showed smaller growth. Body weight prediction equations based in linear measures proposed by Heinrichs et al. (1992) and Reis et al. (2004), did not show to be efficient to predict the weight gain of growing dairy females. The supply of 1 or 2 kg of concentrate ration to growing dairy females, using soybean meal or cottonseed meal as protein sources, can be done without effect on animal performance, with its use conditioned to availability and inputs price. The animals that consumed 2 kg of concentrate ration obtained greater total nitrogen intake (P<0.05), however there was no significant effect of no one of the factors on fecal-N, urine-N, NB in g/day and % of consumed. There was observed effect of interaction between the factors to urine ureic N in g/day and mg/kg LW (P<0.05), in which the animals that received 2 kg of concentrate ration based on soybean meal showed the smallest urine ureic N excretion. However, plasma ureic N in mg/dL did not show any difference between treatments. To urine total purine in mmol/day, urine alantoin in mmol/day, percentage of alantoin relative to total purines, urine uric acid in mmol/day, microbial N in g/day and microbial efficiency in g CP/kg TDN there was also no effect of any of the factors between the treatments. The supply of 1 or 2 kg of concentrate ration to growing dairy heifers, using soybean meal or cottonseed meal as protein sources, can be done without effect on microbial efficiency, although the supply of 2 kg of concentrate ration seems to cause N waste in feces.

ASSUNTO(S)

growth nutricao e alimentacao animal crescimento profitability consumo intake rentabilidade

ACESSO AO ARTIGO

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