Nutritional Performance of Cattle Grazing during Rainy Season with Nitrogen and Starch Supplementation

Abstract

The objective of this work was to evaluate the effects of supplementation with nitrogen and starch on the nutritional performance of grazing cattle during the rainy season. Five rumen cannulated Nellore steers, averaging 211 kg of body weight (BW), were used. Animals grazed on five signal grass paddocks. Five treatments were evaluated: control (forage only), ruminal supplementation with nitrogen at 1 g of crude protein (CP)/kg BW, ruminal supplementation with starch at 2.5 g/kg BW, supplementation with nitrogen (1 g CP/kg BW) and starch (2.5 g/kg BW), and supplementation with nitrogen (1 g CP/kg BW) and a mixture of corn starch and nitrogenous compounds (2.5 g/kg BW), thereby resulting in an energy part of the supplement with 150 g CP/kg of dry matter (DM). This last treatment was considered an additional treatment. The experiment was carried out according to a 5 ×5 Latin square design following a 2×2+1 factorial arrangement (with or without nitrogen, with or without starch, and the additional treatment). Nitrogen supplementation did not affect (p>0.10) forage intake. Starch supplementation increased (p<0.10) total intake but did not affect (p<0.10) forage intake. There was an interaction between nitrogen and starch (p<0.10) for organic matter digestibility. Organic matter digestibility was increased only by supplying starch and nitrogen together. Nitrogen balance (NB) was increased (p<0.10) by the nitrogen supplementation as well as by starch supplementation. Despite this, even though a significant interaction was not observed (p>0.10), NB obtained with nitrogen plus starch supplementation was greater than NB obtained with either nitrogen or starch exclusive supplementation. Supplementation with starch and nitrogen to beef cattle grazing during the rainy season can possibly improve digestion and nitrogen retention in the animal..

Effects of Supplements with Different Protein Contents on Nutritional Performance of Grazing Cattle During the Rainy Season

“…However, the CP content of forage in this study (122.5 g CP/kg DM) was above the typical average values observed in tropical grasses during the rainy season (94.2 g CP/kg DM; Detmann et al, 2014a). Thus, in such a situation, energy supplementation would cause less interference on the dietary protein-to-energy ratio (Figure 1), leading to the absence of deleterious effects on forage intake, which was also observed by Lazzarini et al (2016). At least part of the positive effects of the energy supplement on intake may be associated with stimulation of NMIC (Table 5), which provides an increased level of MP through the additional energy provided via supplementation.…”

“…In ruminant animals, deposition of body tissue corresponds to interactive process in which the efficiency of utilization of metabolizable energy and protein are interrelated (Schroeder and Titgemeyer, 2008; Lazzarini et al, 2016). Upon analysing the increases in energy intake (i.e.…”

“…This dietary adequacy would allow for the utilization of this relative excess of energy from forage and convert it into body weight (BW) gain (Costa et al, 2011c). For this reason, supplementation during the rainy season should focus primarily on protein supplementation (Detmann et al, 2014a; Lazzarini et al, 2016). …”

“…This pattern has characterized changes in the focus of supplementation utilization and type, since energy supplements were widely utilized in the rainy season without showing optimal improvements in nutritional performance and animal production (Detmann et al, 2014a; Lazzarini et al, 2016). However, comparative evaluations regarding protein and energy supplementation on nutritional and metabolic effects on animals under grazing in the tropics remain scarce.…”

Intake, digestibility, and rumen and metabolic characteristics of cattle fed low-quality tropical forage and supplemented with nitrogen and different levels of starch

“…Whereas the nitrogen intake was similar for all supplements (Table 4), the decrease of those variables (i.e., RAN and SUN) could only be obtained through a better efficiency of microbial nitrogen utilization in the rumen. The increase in nitrogen assimilation by providing additional starch was reported under tropical grass feeding [4,7]. Greater microbial nitrogen assimilation implies an increase in metabolisable protein (MP) supply.…”