RESUMO
An experiment was conducted to test the hypothesis that a coarse limestone diet improves productivity, reproductive performance and the calcium utilization of molted broiler breeders. In total, 640 broiler breeder females, 73-week-old and sixty-four 27-week-old cockerels, Cobb 500, were evaluated during 10 weeks, according to a randomized block design composed of 4 treatments with 8 replicates each. Treatments consisted of diets with the inclusion of 100% fine limestone-fine PS (0.2 mm GMD-geometric mean diameter); PS1: 30% fine limestone+70% limestone with 1.0 mm GMD; PS2: 30% fine limestone+70% limestone with 2.0 mm GMD; and PS3: 30% fine limestone+70% limestone with 3.0 mm GMD. Calcium retention in the gizzard of the breeders, bone characteristics, and breeder performance, egg characteristics, eggshell quality, incubation performance, chick quality and yield, chick pre-starter live performance, and chick bone characteristics were determined. There was no significant difference (P>0.05) in the rate of lay, percentage of non-settable eggs, egg weight, egg shape index, egg specific gravity, eggshell weight, thickness, and percentage hatchability and egg weight loss of broiler breeders fed with diets with different limestone particle sizes. The chick quality and yield, chick pre-starter live performance, and chick bone characteristics were not affected (P>0.05) by any of the limestone particle sizes. It was concluded that live and reproductive performance parameters of broiler breeders post molting is not affected by limestone particle size in the feed.
Assuntos
Carbonato de Cálcio/metabolismo , Cálcio da Dieta/metabolismo , Galinhas/fisiologia , Tamanho da Partícula , Ração Animal/análise , Animais , Osso e Ossos/efeitos dos fármacos , Osso e Ossos/fisiologia , Dieta/veterinária , Casca de Ovo/efeitos dos fármacos , Casca de Ovo/fisiologia , Feminino , Distribuição Aleatória , Reprodução/efeitos dos fármacosRESUMO
This study examined the relationship between birth weight and growth performance when suckling piglets were reared in litters standardized by birth weight. Forty-four gilts (Landrace × Large White) due to farrow during the same week were selected. Piglets born to those gilts were individually weighed at birth and cross-fostered to obtain litters with 11 piglets and standardized birth weight (CV, lower than 5%). Based on average birth weight, 4 litter weight classes were established: class 1 (> 1.10 kg to ≤ 1.33 kg), class 2 (> 1.34 kg to ≤ 1.46 kg), class 3 (> 1.47 kg to ≤ 1.57 kg), and class 4 (> 1.58 kg to ≤ 1.88 kg). At 21 d of age, piglets were weighed to determine BW and calculate ADG and weight gain relative to birth weight. A completely randomized experimental design was used with birth weight classes as treatments. At 21 d of age, the average BW of piglets from the heaviest birth weight class (5.67 kg) was greater (P < 0.05) than the lightest class (5.06 kg); however, all classes had the same ADG (P < 0.05). There was a positive correlation (r = 0.184; P < 0.01) between birth weight and weight at 21 d of age, but birth weight was not correlated (r = -0.040; P = 0.37) with ADG during the suckling phase. Therefore, piglet birth weight did not influence weight gain when piglets were reared by sows in litters with standardized birth weight.