Levels of Supplementation for Grazing Beef Heifers

Abstract

The objective of this experiment was to evaluate the effect of providing different levels of a supplement on the nutritional characteristics and productive performance of heifers on pasture during the rainy-dry transition and dry season in Brazil or tropical area. Thirty crossbred heifers with predominance of Zebu breed were used in a completely randomized experimental design. Treatments consisted of a mineral supplement and 0.5, 1.0, 1.5, or 2.0 kg/animal/d of a protein supplement containing 300 g crude protein (CP)/kg of dry matter (DM). In the rainy-dry transition season there was quadratic effect of the protein supplementation (p<0.10) on daily weight gain (DWG). A linear relationship (p<0.10) was found between increasing supplement intake and intakes of DM, organic matter (OM), crude protein (CP), ether extract (EE), non fibrous carbohydrates (NFC) and total digestible nutrients (TDN). Coefficients of apparent digestibility of CP, EE, and NFC increased linearly (p<0.10) with increasing supplement levels, but there was no effect on the DM apparent digestibility (p>0.10); the microbial efficiency (g CPmic/kg TDN) and the relationship of microbial nitrogen flow with nitrogen intake (g/g nitrogen intake) were negative linear profiles. In the dry season, the descriptive pattern least squares means showed a trend of stabilization of DWG from the supply of 0.98 kg of protein supplement; the intakes of DM, OM, CP, EE, NFC, and TDN showed increasing linear relationship (p<0.10) with protein supplement levels; the means of apparent digestibility coefficients of the different dietary fractions presented a linear-response-plateau (LRP); the microbial nitrogen flow (g/d) showed positive linear profile (p<0.10) for supplementation levels. It is concluded that supplementation improves the productive performance of grazing heifers and that 1.0 kg/d of supplement per animal gives the maximum increment of weight gain.

Morphological characteristics, nutritive quality, and methane production of tropical grasses in Brazil

“…The genus Urochloa (Syn. Brachiaria) is the most dominant, representing 50% of pastures of the country because of its remarkable adaptability and productivity in tropical climate conditions (Cabral et al, 2014;Demarchi et al, 2016). However, despite being more challenging and demanding for soil fertility, the use of Megathyrsus maximus is increasing as an option to forage grass due to its high-leaf production and nutritional value, factors that may allow the achievement of a superior animal performance (Fernandes et al, 2014).…”

Metabolic responses, performance, mammary gland development and gene expression in liver and muscle of Holstein × Gyr crossbred heifers grazing intensively-managed brachiaria decumbens supplemented with varied crude protein and association of housing and management practices with milk yield, milk composition, and fatty acid profile, predicted using fourier-transform mid-infrared spectroscopy, in farms with automated milking systems

“…However, SUP animals had lower microbial efficiency in g/kg of digestible OM and g/kg of CPI. Thus, we observed an increase in the efficiency of nonsupplemented animals because of a severe deficiency in rumen N or ammonia (Cabral et al, 2014). Thus, non-supplemented animals were highly dependent on recycled N to keep microbial activity in the rumen environment (Detmann et al, 2014), increasing their efficiency per N intake unit.…”