Paulo Sérgio Rosa

Influência da temperatura de incubação em ovos de matrizes de corte com diferentes idades e classificados por peso sobre os resultados de incubação

A total of 61,920 eggs from a single commercial line of broiler breeders was incubated. The effect of different incubation temperatures (T), measured by the wet bulb thermometer in degrees Celsius (oC), was evaluated with eggs classified by weight (P) from broiler breeders with different ages (I). Evaluation of the percentages of total hatched, hatchability, egg weight loss and embryo mortality was performed. A completely randomized experimental design in a factorial 3 x 4 x 5, representing, respectively, three T (28.6, 29.6 and 30.6oC), four I in weeks (34, 39, 53 and 63) and five P, with weight averages (g) of 60.0, 65.1, 66.6, 69.0, and 73.2, was used. Total embryo mortality (Metot) was lower at T 28.6oC. At 39-weeks of age, Metot was the lowest, and for P, ME had the lowest averages. There was a significant effect of factors age and egg weight and of the interactions age x egg weight, temperature x age and temperature x age x egg weight on average egg weight (Povo). For the percentage of egg weight loss up to transference (Pppeso), there was a significant effect of T, I and P. The percentages of the total hatched and hatchability were optimized with 10.3% weight loss during incubation at 28.6oC.

Empenamento, níveis hormonais de triiodotironina e tiroxina e temperatura corporal de frangos de corte de diferentes genótipos criados em diferentes condições de temperatura

Feather growth, plasmatic levels of T3 and T4 and body temperature were evaluated in broiler raised under different temperatures. The two evaluated broiler lines were Cobb-500 and ISA-Label JA57. One hundred and eighty birds of each line were raised under cold, neutral or hot temperatures in a complete randomized design with 3 x 2 factorial scheme (3 temperatures and 2 lines), with 8 repetitions. There was a significant increase in T3 levels of birds raised under cold temperature but, under hot temperature, these levels decresed. Under high temperatures, ISA Label birds showed the higest levels of T4. The Cobb birds showed significant T4 decrease under both, cold and hot temperatures, at 42 days of age; and at 21 days of age this decrease was observed only under hot temperature. There was lower feathering at 42 days of age when birds were raised under hot temperature. ISA Label broilers had a better feather growth than those of Cobb line. Birds raised in a hot environment had higher temperature. Cobb broilers had a significant increase in internal temperature when raised under hot conditions. However ISA Label broilers maintained their body and internal temperature, independently of the raising temperature. It was concluded that environmental temperature affects feathering of broiler chickens from lines selected for fast body weight gain, which also showed low heat tolerance, demonstrated by the higher body and internal temperatures.

Desenvolvimento folicular de embriões de frangos de corte de diferentes genótipos expostos ao estresse térmico crônico

The objective of this research was to evaluate the tegument modification (feather morphogenesis) in embryos of broiler chicken, of different growth standard breeder lines, obtained from eggs incubated under different temperatures. Eggs of Cobb 500 and ISA JA57 breeders lines, were proportionally distributed in three incubators. From the first (D1) to the sixth day (D6) of incubation, temperature was maintained standard at 37.8°C. From the seventh day (D7) until the moment of the birth on the twenty one days (D21), temperature was reduced to 36.8°C (Cold) in one of the incubators, and in another incubator was increased to 38.8°C (Hot). The temperature in the third incubator was maintained at 37.8°C (Control). It was used a completely randomized design with factorial 3 x 2 (temperature of incubation and breeder lines). Incubation temperature and breeder factor do not modify the follicular density of the feather (average number of follicles per area of 337.5µm2) in the femoral and dorsal tract of until eleven days (D11) embryos. An increase of follicular density in the dorsal region of sixteen days (D16) embryos was observed, because the temperature increased, of the remaining until the moment of birth, demonstrating that embryos incubated above the recommended temperature (38.8°C) present higher follicles density in the dorsal tract. However, follicles morphogenesis remained unaltered.

Produção e qualidade de ovos em reprodutoras de frangos de corte com horário de arraçoamento diferenciado

Four feeding schedule were investigated for broiler breeders: at 6:30 am; 50% feeding at 6:30 am and 50% at 3:30 pm (dual); at 11:00 am, and at 3:30 pm. Arbor Acres breeders were randomly assigned to 48 boxes, with 12 replicates of 27 females and three males each. The nutritional levels and management procedures were those recommended for strain. The variables studied were: total egg production, nest, clean and broken egg production, in six collections (6:30 am, 9:00 am, 11:00 am, 1:30 pm, 3:30 pm and 5:30 pm); egg weight and egg specific gravity, grouped in three collections (9:00 am, 1:30 pm and 5:30 pm). Analysis of variance was used. Means were compared using Student t test for traits and collection and polynomial regression analysis for age. The collection and feeding schedule effects were significant for all traits, except for broken eggs, in which feeding schedule was not significant. The maximum egg production was obtained at 9:00 am for feeding schedule at 6:30 am (22.78 ± 0.36%) and dual (20.26 ± 0.33%), and at 1:30 pm for feeding schedule at 11:00 am (20.35 ± 0.39%) and at 3:30 pm (19.25 ± 0.38%). Female broiler breeders under the dual and at 3:30 pm feeding schedule showed egg weight of 71.0 ± 0.3 g, which was at least equal to the other feeding schedule in any collection. The egg specific gravity for feeding schedule at 11:00 am (1.0788 ± 2) and 3:30 pm (1.0799 ± 2) were higher than the other feeding schedule. Eggs from older female broiler breeders and eggs collected in the first hours of the day were heavier and had thinner eggshell than those from younger females and eggs collected later in the day. The dual feeding schedule could be an alternative to feeding schedule at 6:30.

Performance of female broiler breeders submitted to different feeding schedules

The performance of Arbor Acres broiler breeders (1,296 females; 144 roosters) was evaluated when submitted to the following treatments (T): T1 = feeding at 6:30 a.m. (control); T2 = 50% feeding at 6:30 a.m. and 50% at 3:30 p.m. (dual feeding); T3 = feeding at 11:00 a.m.; and T4 = feeding at 3:30 p.m. Treatments were randomly distributed in 48 pens. There were 27 females and 3 males in each pen and 12 repetitions per treatment. Nutrition and management were as recommended for the commercial strain. It was evaluated age at first egg (AFE), total egg production (TEP), number of days with production above 80% (DAP80), laying peak (P), female mortality (MOR), and gross profit margin (GM) per hen. Data were submitted to analysis of variance and means were compared by Students t-Test. TEP of T1 (186.3±2.3) and T2 (186.5±1.5) were higher (p 0.10) among treatments. GM per hen was better (p<0.05) in T1 and T2 hens. Control and dual treatments were more efficient than other treatments. It was concluded that it is possible to change conventional feeding managements by the dual feeding system.

Influence of feeding time on sexual maturity and carcass composition in female broiler breeders

One thousand two hundred and ninety six Arbor Acres females and 144 males were used to study the influence of feeding time on sexual maturity and carcass composition. Treatments were: T1 = feeding at 6:30 am, T2 = 50% feeding at 6:30 am and 50% at 3:30 pm (dual), T3 = feeding at 11:00 am, T4 = feeding at 3:30 pm. Nutrition and management were as recommended to the commercial line. Variables studied were: sexual maturity at 5% production (SM), mean egg production percentage (PEP) body weight (BW), carcass composition, tibia weight (TIBW) and tibia calcium (Ca) and phosphorus (P) contents. Analysis of variance was used, and the means were compared using Students t test. T2 females reached SM at 25.92 weeks, which was earlier (p 0.10) on carcass dry matter (DM), ether extract (EE), crude protein (CP) and ash (ASH). DM, EE, TIBW, Ca and P increased (p<0.05) whereas CP and ASH decreased with age. Time of feeding influenced body weight, but not carcass composition. Hens fed twice a day had earlier sexual maturity and similar egg production compared to those fed once at 6:30 am.