Comparison of mathematical and comparative slaughter methodologies for determination of heat production and energy retention in broilers

Abstract

Understanding factors affecting ME availability for productive processes is an important step in optimal feed formulation. This study compared a modelling methodology with the comparative slaughter technique ( CST ) to estimate energy partitioning to heat production and energy retention ( RE ) and to investigate differences in heat dissipation. At hatch, 50 broilers were randomly allocated in one of 4 pens equipped with a precision feeding station. From day 14 to day 45, they were either fed with a low-ME (3,111 kcal/kg ME) or a high-ME (3,383 kcal/kg ME) diet. At day 19, birds were assigned to pair-feeding in groups of 6 with lead birds eating ad libitum (100%) and follow birds eating at either 50, 60, 70, 80, or 90% of the paired lead's cumulative feed intake. Heat production and RE were estimated by CST and with a nonlinear mixed model explaining daily ME intake ( MEI ) as a function of metabolic BW and average daily gain ( ADG ). The energy partitioning model predicted MEI = (145.10 + u ) BW 0.83 + 1.09 × BW −0.18 × ADG 1.19 + ε. The model underestimated heat production by 13.4% and overestimated RE by 22.8% compared with the CST. The model was not able to distinguish between net energy for gain values of the diets (1,448 ± 18.5 kcal/kg vs. 1,493 ± 18.0 kcal/kg for the low-ME and high-ME diet, respectively), whereas the CST found a 148 kcal/kg difference between the low-ME and high-ME diets (1,101 ± 22.5 kcal/kg vs. 1,249 ± 22.0 kcal/kg, respectively). The estimates of the net energy for gain values of the 2 diets decreased with increasing feed restriction. The heat increment of feeding did not differ between birds fed with the low- or high-ME diet (26% of MEI). Additional measurements on heat dissipation, physical activity, and immune status indicated that the energetic content of the diet and feed restriction affect some parameters (shank temperature, feeding station visits) but not others (leukocyte counts, heterophil to lymphocyte ratio, and immune cell function).

Modeling life-time energy partitioning in broiler breeders with differing body weight and rearing photoperiods

“…The results could have been confounded by dietary factors, as the diet was switched at week 23 (from a grower to peak layer diet). However, it was previously concluded that diet composition did not affect the heat increment feeding in broilers ( van der Klein et al., 2020 ). In immature feed restricted birds, it is possible that part of the increase in ME intake will directly partition to gain, predominantly toward lean tissues.…”

Modelo para predizer as exigências em proteína bruta para codornas japonesa em postura

“…As diferenças de resultados podem estar associadas a espécies e linhagens diferentes (Silva et al, 2012), consequentemente suas exigências também serão devidas suas características metabólicas particulares. Além disso, diversos fatores ambientais podem afetar nessa divergência de estimativas de exigência de bruta para mantença (PBm), como: temperatura (Aksit et al, 2013), empenamento (KIM et al, 2016, nível de consumo (Mauricio et al, 2018), genética (Wang et al, 2022), técnica do abate comparativo (Klein et al, 2020) e balanço de nitrogênio (Jordão Filho et al, 2011;Silva et al, 2004a).…”

Redes neurais artificiais para o gerenciamento da indústria avícola: uma simulação baseada na cadeia de produção de frangos de corte

“…Além disso, a RNA tem sido utilizada para avaliar a depleção de linfócitos na bolsa de Fabricius e no timo (3,11,12) . Outros modelos matemáticos e sistemas de inteligência também têm sido desenvolvidos para possibilitar o gerenciamento de dados em diversas áreas da cadeia produtiva avícola (13)(14)(15)(16) .…”