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Effect of body weight trajectories on broiler breeder efficiency and fat deposition during rearing

2022 CPRF,Environment and Management
A study was designed to analyze the effect of broiler breeder pullet BW on efficiency and fat deposition. We hypothesized that early BW growth would increase BW, abdominal fat pad, and FCR, and that BW uniformity would be higher in a precision feeding (PF) system compared to a conventional (CON) system. Two concurrent PF studies plus a standard CON system were implemented to 21 wk of age. A total of 678 day-old Ross 308 broiler breeder females were randomly assigned to various BW trajectories. In both PF studies the BW trajectories were designed using a 3-phase Gompertz model, where gi was the amount of gain occurring in phase i; bi was the rate of maturing of phase i; I was the inflection point of phase i; and t was age (wk). Both PF experiments had a 2 x 6 factorial treatment arrangement. Experiment 1 (Exp1) trajectories had 2 levels of g1 (prepubertal growth): standard, where g1 was equivalent to the phase 1 growth estimated from the breeder-recommended (BR) target, or a 20% shift from g2 (pubertal growth) to g1; and six I2 ranging from 15 to 23 wk. Experiment 2 (Exp2) trajectories had two rates b2: standard or 50% greater; and six shifts of growth from g2 to g1, ranging from -10 to 40% of BR g2. CON birds were grown to the BR target BW. Body weight and feed intake (FI) of CON birds were recorded once per week. Feed intake and BW were recorded daily, and abdominal fat pad weight was recorded at 21 wk of age in the PF system. FCR and coefficient of variation (CV) for BW were calculated weekly. PF experiments were submitted to 3-way ANOVA, with g1 and I2 (Exp1) or b2 and g2 to g1 shift (Exp2), and age as sources of variation. ANCOVA was used to analyze abdominal fat pad data. Comparisons among CON and PF systems were made using a 2-way ANOVA with feeding system and age as sources of variation. BW differed according to the respective BW trajectories in both PF system experiments (P < 0.05). In Exp1, I2 did not affect FCR, but standard g1 pullets had a lower FCR (3.77) compared to the 20% shift from g2 to g1 (3.85; P < 0.05). In Exp2, b2 did not affect FCR, but FCR increased as gain was shifted from the pubertal to prepubertal phase (P < 0.05). At 21 wk of age, fat pad increased 0.22% per wk that I2 was advanced in Exp1 (P < 0.05), but fat pad did not differ in Exp2. BW CV was 0.9% in the PF system compared to 18.4% in the CON system (P < 0.05). In summary, early BW gain increased FCR, and the PF system yielded substantial uniformity improvement.
Tags :
body weight,broiler breeder,fat deposition,rearing
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PhD Student

University of Alberta

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