ABSTRACT
A suplementação proteico-energética (SPE) é uma estratégia adequada à bovinocultura de corte no período seco do ano, embora sua adoção equivocada possa comprometer seu benefício/custo. O objetivo deste estudo foi avaliar o desempenho de novilhas Nelore em pastagem diferida de Urochloa decumbens sob dois períodos de SPE, e realizar análise econômica desses sistemas de produção. O experimento foi conduzido sob delineamento inteiramente ao acaso, com 147 e 55 dias de SPE (sistemas 1 e 2, respectivamente), de 21/06 a 15/11/2016, com 16 e 20 novilhas nos sistemas 1 e 2, respectivamente. Os dados de desempenho foram analisados utilizando-se o PROC MIXED do SAS®, e as médias comparadas por PDIFF (P<0,05). Os pesos médios foram semelhantes (P>0,05) entre os sistemas de produção nas pesagens de 21/06, 12/07, 02/08, 23/08 e 15/11/2016. Os valores presentes líquidos foram positivos sob a taxa anual de desconto de 4%, sendo viáveis financeiramente. Por apresentarem taxa interna de retorno superior à taxa mínima de atratividade, os sistemas foram atrativos para investimento. Foi obtido balanço econômico positivo de R$ 25,26/animal para substituição do sistema 1 pelo sistema 2. A redução de 92 dias na SPE proporciona desempenho semelhante entre novilhas e maior eficiência econômica do sistema de produção.(AU)
Protein-energy supplementation (SPE) is an adequate strategy for beef cattle during drought season of the year, although the wrong adoption might compromise its cost/benefit ratio. The aim of this study was to evaluate Nellore heifers' performance under SPE periods and to draw economic analysis of production systems. The experiment was conducted under a completely randomized design, with two systems: 147 and 55 days of SPE (Systems 1 and 2), from 06/21/2016 to 11/15/2016, with 16 and 20 heifers to Systems 1 and 2, respectively. Performance data were analyzed by SAS® PROC MIXED and means compared by PDIFF (P< 0.05). The weight means were similar between the production systems (P> 0.05) at weighing of 06/21, 07/12, 08/02, 08/23 and 11/15/2016. The net present values were positive under annual discount rate of 4%, being financially viable. By presenting internal return rate higher than the minimum attractiveness rate, the systems were attractive for investment. Positive economic balance was obtained of R$ 25.26/animal to replace System 1 by 2. The reduction of 92 days in SPE provides similar performance between Nellore heifers and greater economic efficiency of the production system.(AU)
Subject(s)
Animals , Female , Cattle , Dietary Proteins/administration & dosage , Pasture/analysis , Diet/veterinary , Animal Feed/analysis , Animal Nutritional Physiological PhenomenaABSTRACT
Milk fatty acids profile was evaluated using 12 Holstein cows producing 15 kg/day of milk with 4.0% of fat. The animals were assigned to four treatments in a 2 x 2 factorial arrangement (two tropical grasses - Brachiaria brizantha cv. Xaraés and Panicum maximum cv. Tanzania, supplemented with two concentrate levels - 3 and 6 kg/cow/day) in a completely randomized block design. There was no effect of forage and concentrate level (P>0.05) on concentrations of rumenic, vaccenic, (C18: 1 trans-11) and oleic acids in milk fat (mean values of 1.01, 1.79, and 22.55 g/100 g of total fatty acids, respectively). The concentrations of lauric (C12:0), myristic (C14:0), and palmitic (C16:0) acids were also unaffected by treatments (mean values of 2.63, 9.77, and 27.44g/100g of total fatty acids, respectively). Overall, the results illustrate the potential of tropical grasses in producing milk containing a more desirable fatty acids profile in terms of human health.