Abstract
ObjectiveObjectives were to estimate energy and protein requirements of dairy crossbred steers, as well as to evaluate equations previously described in the literature (HH46 and CS16) to predict the carcass and empty body chemical composition of crossbred dairy cattle.MethodsThirty-three Holstein×Zebu steers, aged 19±1 months old, with an initial shrunk body weight (BW) of 324±7.7 kg, were randomly divided into three groups: reference group (n = 5), maintenance level (1.17% BW; n = 4), and the remaining 24 steers were randomly allocated to 1 of 4 treatments. Treatments were: intake restricted to 85% of ad libitum feed intake for either 0, 28, 42, or 84 d of an 84-d finishing period.ResultsThe net energy and the metabolizable protein requirements for maintenance were 0.083 Mcal/EBW0.75/d and 4.40 g/EBW0.75, respectively. The net energy (NEG) and protein (NPG) requirements for growth can be estimated with the following equations: NEG (Mcal/kg EBG) = 0.2973(±0.1212) ×EBW0.4336(±0.1002) and NPG (g/d) = 183.6(±22.5333)×EBG−2.0693(±4.7254)×RE, where EBW, empty BW; EBG, empty body gain; and RE, retained energy. Crude protein (CP) and ether extract (EE) chemical contents in carcass, and all the chemical components in the empty body were precisely and accurately estimated by CS16 equations. However, water content in carcass was better predicted by HH46 equation.ConclusionThe equations proposed in this study can be used for estimating the energy and protein requirements of crossbred dairy steers. The CS16 equations were the best estimator for CP and EE chemical contents in carcass, and all chemical components in the empty body of crossbred dairy steers, whereas water in carcass was better estimated using the HH46 equations.
Highlights
Among the indirect methods available, the method that predicts body composition from equations based on the 9th to 11th rib section composition, which was first proposed by Hankins and Howe (HH46) [7], is wide spread due the ease of use, reduced cost involved, and speed of the process
The values calculated by the equations proposed in this study, the net energy requirement for maintenance (NEM) and net energy requirement for gain (NEG) estimated by NASEM [1] were approxi
The metabolizable protein requirement for maintenance (MPM) and NPG estimated by NASEM [1] were approximately 17 and 59 g/d below the value calculated by equations developed in the current study
Summary
24 242 TitTleitolef tohfethmeamnuasncursipcrt:ipNt:uNtriuetnriternetqrueiqreumiremntesnatnsdanedvaelvualtuioantioonf eoqfueaqtui tmiltteihpoeoonsfmoittfihaodnenaumiosrfycaAVhprdntIconiSaturplipioS.msrtssy:c3Ns:r4N/Bbci/2rp,riudoeoN7ttods:rs6osiicNse.b5.otnire-u4ert0etg:drr1r5/iesse851.qtn98eu0te-i.e5rrr5eesI67Sm.q61uSe3iNAnr/etpsam2rja7iaelnn6s2dt5.s01e-290avn1.2a0dl3u85ea2vt9iaolnuaotfioenquoafteioqnusattioonpsretdoicptrecdhiecmt cichael22mb56ioc22da56yl body comcopmospitoisointionf doafidryaicryrocsrsobsrsebdrsetdeesrtes.ers. Silva et al (2021) Anim Biosci 34:558-566 lengthy, laborious, and expensive Due to these challenges, indirect methods have been developed for estimating body composition [7,8,9]. Prediction equations to estimate the growth pattern and composition of gain of Holstein×Zebu crossbreds have not been reported In this respect, Costa e Silva et al (CS16) [2] developed equations for estimating body composition of crossbred dairy cattle. Costa e Silva et al (CS16) [2] developed equations for estimating body composition of crossbred dairy cattle They still need to be evaluated with an independent database in order to be widely and reliably adopted. The objectives were to estimate energy and protein requirements of dairy crossbred steers, as well as to evaluate the goodness of fit of prediction equations developed by HH46 [7] and CS16 [12] to predict the carcass and empty body chemical composition of crossbred dairy cattle
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