Nutritional requirements of energy, protein and macrominerals for maintenance and weight gain of young crossbred Nellore × Holstein bulls on pasture

Marlos Oliveira Porto,Sebastião De Campos Valadares Filho,Victor Rezende Moreira Couto,Maykel Franklin Lima Sales,Jucilene Cavali,Mário Fonseca Paulino,Edenio Detmann,Ériton Egidio Lisboa Valente

doi:10.1590/s1516-35982012000300037

Marlos Oliveira Porto, Sebastião De Campos Valadares Filho + Show 6 more

Open Access

https://doi.org/10.1590/s1516-35982012000300037

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Abstract

The objective of this study was to estimate requirements of energy, protein and macrominerals of young Nellore/Holstein crossbreds bulls supplemented on pastures of Brachiaria decumbens Stapf. Thirty-five young bulls, at 8.53±0.18 months of age and with initial body weight of 230.6±6.1 kg were used. Ten animals were slaughtered as reference, in different weight range, and the other animals were slaughtered at the end of the experimental period. For estimate of net energy requirements for weight, a regression equation between log of retained energy (RE) and log of empty body weight gain (EBWG) was constructed. Net requirements of Ca, P, Mg, Na and K were determined by the equation Y' = a.b.Xb-1, in which a and b represent the intercept and the coefficient of equation of prediction of macrominerals in body content, respectively. Requirements of metabolizable energy for maintenance (MEm) were obtained from retained energy in function of metabolizable energy intake (MEI). The requirements of MEm of Nellore/Holstein crossbreds young bulls on pasture was 125 kcal/EBW0.75/day. The efficiency of ME utilization for maintenance (k) of grazing Nellore/Holstein crossbred young mbulls was 0.58 and 0.24 for gain. The total metabolizable protein requirements for an animal with 400 kg and with average daily gain of 1.0 kg, were 638.36 g/day. The dietetic requirements of Ca and P for an animal with 400 kg BW were 0.49 and 0.21% of DM, respectively. Daily metabolizable energy requirement for maintenance of grazing Nellore/Holstein crossbred young bulls was 11.6% greater than the values found for cattle in feedlot in Brazil (112 kcal/kg EBW0.75).

Highlights

IntroductionThe success of any cattle rearing system, either in feedlot or pasture, depends on the adequacy of the diet to the nutritional needs of animals
The Brazilian livestock is predominantly developed in production systems which use pasture as the main ingredient of the diet because it is a low cost way of producing milk and beef in the tropics.The success of any cattle rearing system, either in feedlot or pasture, depends on the adequacy of the diet to the nutritional needs of animals
Metabolizable energy requirement for maintenance of grazing Nellore/Holstein crossbred young bulls was 11.6% greater than the values found for cattle in feedlot in Brazil (112 kcal/kg EBW0.75)

Summary

Introduction

The success of any cattle rearing system, either in feedlot or pasture, depends on the adequacy of the diet to the nutritional needs of animals. Some studies on nutritional requirements for cattle raised on pasture (Zervoudakis et al, 2002; Fregadolli, 2005; Moraes et al 2009; Paixão, 2008; Sales et al 2010; Sales et al, 2011) have been developed in Brazil, but the amount of information available is still considered small for the development of equations that are considered as reliable for use in diet formulation programs, especially regarding the supplementation of these animals

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