Energy to protein ratios in supplements for grazing heifers in the rainy season
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Energy to protein ratios in supplements for grazing heifers in the rainy season Alyce Raiana Monteiro dos Santos 1 & Carla Heloísa Avelino Cabral 2 & Carlos Eduardo Avelino Cabral 2 & Lívia Vieira de Barros 1 & Jackelliny Melo de Barros 2 & Welton Batista Cabral 2 & Milene Rodrigues Dias 3 Received: 20 December 2018 / Accepted: 28 May 2019 # Springer Nature B.V. 2019
Abstract This study evaluated the effect of energy and protein supplementation on the nutritional characteristics, ingestive behavior, and productive performance in grazing heifers during the rainy season. Forty crossbred heifers (Nelore breed predominance) were used in the study, with an age of 14 months and an initial mean weight of 182 ± 1.13 kg. The treatments consisted of mineral supplementation ad libitum (control) and three supplements formulated to contain an energy: protein ratio (TDN:CP) of 1.13, 2.62, and 4.06; these were denominated as low (LC, 0.5 kg animal d−1), medium (MC, 1.0 kg animal d−1), and high consumption (HC, 1.5 kg animal d−1), respectively, in order to guarantee an intake of 300 g of crude protein (CP) animal−1 d −1, with variation in energy content. There was a difference (P < 0.05) in crude protein intake, with a 44% reduction for the LC treatment in relation to HC. The lowest grazing time (398 min) was observed with the MC treatment. Urinary urea-N (UreaN) was lower for control animals (P < 0.05). Average daily gain (ADG) was lower for the control animals than for the supplemented animals (P < 0.05); there was no difference in ADG between the animals receiving supplementation. High supplementation levels and TDN:CP ratios are not recommended because they do not justify the increased costs of supplementation. Therefore, when forage presents great nutritional characteristics, it is possible to optimize the performance of the animals with low to medium consumption supplementation. Keywords Ingestive behavior . Nutritional characteristics . Performance . Ruminant nutrition
Introduction In the cattle production system in Brazil, pasture is the main source of food, due to its lower cost (Gaspar et al. 2017; McLennan et al. 2017). Animals raised in this system, only having forage as a source of nutrients, may require more time to reach the finishing weight necessary for slaughter,
compared with supplemented animals. Moreover, the stocking rate of pasture is lower, which leads to the need for larger areas to feed the same number of animals, lowering the productivity and profitability of the area in question (Poppi et al. 2018). Productivity is compromised because there is a strong change in performance due to the quantitative and qualitative variation in forage production during the year, mainly due to
* Alyce Raiana Monteiro dos Santos [email protected]
Welton Batista Cabral [email protected] Milene Rodrigues Dias [email protected]
Carla Heloísa Avelino Cabral [email protected] 1
Faculdade de Agronomia e Zootecnia, Universidade Federal de Mato Grosso, Avenida Fernando Corrêa da Co
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