Proporção de volumoso na dieta de vacas Holandesas e sua influência na produção e composição do leite em diferentes períodos de lactação

Abstract

One of the most costly factors in the sector is food, which can correspond to up to 70% of the production costs, and the biggest expense comes from the purchase of grains to supplement the animals' diet. The objective of the present work was to evaluate, through a systematic review of the literature, the voluminous: concentrate ratio and lactation period of dairy cows on the nutrient contents present in the diet and milk composition, also verifying the relation with the production. In the systematic review of the literature, data from 27 publications (scientific articles, dissertations and theses) were used, which were tabulated and organized using Microsoft Excel®. Data were analyzed according to the proportion of dietary bulk (60:40, 50:50 and 45:55) and lactation period (0-150 days, 150-300 days). The experimental design was completely randomized with factorial arrangement 3 x 2 (3 proportion of bulky and 2 stages of lactation). The data were submitted to analysis of variance, and the means were compared by the t test at the 5% probability level. Statistical analyzes were performed through the application of static analysis software of the SAS program (2000). The proportion of bulky in the diet did not influence the variables of milk production (kg) and milk fat, lactose and urea nitrogen (%). Regarding the diet, it was observed that, regardless of the proportion of roughage, the values related to the percentage of crude protein, dry matter, organic matter and ethereal extract were similar. Nevertheless, the variables of mineral matter content, neutral detergent fiber and dietary acid detergent fiber, differed significantly. In the same way, live weight (kg) was influenced by diet and may be associated with dry matter intake, which was also significant. The lactation period had an influence on live weight (kg), dry matter intake (% PV / day) and milk fat content. In relation to the diet there was influence in the neutral detergent fiber and mineral matter contents. There was no difference in the lactation period in the other milk components, which may be a reflection of the selection of high production cows that do not allow the visualization of differences in milk quality in the different stages of lactation.