Effect of final photoperiod and twenty-week body weight on sexual maturity and early egg production in broiler breeders

Animal and Poultry Science, University of KwaZulu-Natal, Pietermaritzburg, South Africa.
Poultry Science (Impact Factor: 1.67). 04/2006; 85(3):377-83. DOI: 10.1093/ps/85.3.377
Source: PubMed


Cobb broiler breeder pullets, grown to achieve 2.19 kg (normal growth) or 2.41 kg (faster growth) BW at 20 wk, were given continuous light during the first 2 d posthatch, were reared on 8-h photoperiods between 2 d and 20 wk of age, and were then transferred abruptly to 10-, 11-, 12-, 14-, 16-, or 18-h photoperiods at 20 wk. Controls remained on 8 h at 20 wk. The birds were reared on a litter-floor from 1 d and transferred at 15 wk to individual cages. Mean age at first egg (AFE) was advanced by 12 d, compared with controls, for the transfer to 10 h, and progressively earlier for longer photoperiods until a 25-d advance for 14 h; AFE was similar for pullets transferred to 14, 16, and 18 h. A quadratic regression indicated that a transfer to 15 h would induce the earliest maturity. On average, accelerating growth by about 10 d advanced AFE by 4 d, but the difference was larger for transfers to a more stimulatory photoperiod. Body weight at first egg increased by about 20 g for each 1-d delay in first egg and was 110 g heavier for the faster growth pullets than for controls. Egg numbers to 39 wk increased by 0.75 for each 1-d earlier AFE. Mean egg weight was negatively related to photoperiod, decreasing by 0.3 g per 1-h, but positively linked to AFE, increasing by 0.1 g for each 1-d delay in AFE. Faster growth did not significantly increase egg numbers or mean egg weight, but it did increase egg output to 39 wk by 150 g. The data suggest that broiler breeders reared on 8-h daylengths do not need more than a 14-h photoperiod in the laying period to optimize sexual development or egg production. Typically recommended BW targets for broiler breeders (2.1 to 2.2 kg) appear to be optimal for egg production. Responses to the lighting treatments were independent of those to 20-wk BW.

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    ABSTRACT: An experiment with broiler breeder pullets was undertaken to determine the effect of pattern of light stimulation and pullets body weight at 20 wk of age on various production parameters, body weight and age at onset of lay. Two light stimulation treatments were used: abrupt (ALS) and step-up (SLS). Pullets were randomly assigned to one of three body weight groups: low weight (1800 g), medium weight (2200 g), or heavy weight (2600 g) at 20 wk of age. The results obtained indicated that pattern of light stimulation and weight at 20 wk did not markedly affect egg production, however, pullets exposed to SLS or ALS produced the lightest eggs. A numerical advancement occurred in age at first egg due to SLS. Significant weight gain occurred in low weight pullets due to SLS. The results of this experiment indicated that SLS of low weight broiler breeder pullets represents a viable means for Increasing weight gain and advancing onset of egg laying.
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    ABSTRACT: This study was undertaken to assess dietary ME and CP concentrations for optimum growth performance of Pearl Gray guinea fowl pullets. In a 3 x 3 factorial arrangement, 540 one-day-old Pearl Gray guinea keets were randomly assigned to experimental diets with 2,900, 3,000, and 3,100 kcal of ME/kg of diet, each containing 20, 22, and 24% CP, respectively, from 0 to 8 wk of age (WOA). From 9 to 16 WOA, these diets were adjusted to contain 3,000, 3,100, and 3,200 kcal of ME/ kg, and each had 17, 19, and 21% CP, respectively. Each dietary treatment was replicated 4 times, and feed and water were provided ad libitum. Body weight and feed consumption were measured weekly. Mortality was recorded as it occurred. Overall, feed consumption was higher in birds on 2,900 and 3,000 kcal of ME/kg of feed and the 24 and 21% CP diets than other dietary treatments at 0 to 8 and 9 to 16 WOA, respectively. When compared with other dietary treatments, cumulative BW gains were higher (P < 0.05) in birds fed 3,000, 3,000 and 3,100, and 3,100 and 3,200 kcal of ME/kg of diet at 2 to 5, 6 to 8, and 9 to 16 WOA, respectively. Pullets receiving 24 and 21% CP diets also exhibited higher BW gains than other dietary treatments at 0 to 8 and 9 to 16 WOA, respectively. Feed conversion ratios were lower (P < 0.05) in birds fed 3,000, 3,100, and both 3,100 and 3,200 kcal of ME/kg of diet at 1 to 5, 6 to 8, and 9 to 16 WOA, respectively, than other dietary treatments. Pullets fed 24% CP diets and either 17 or 19% CP diets exhibited lower (P < 0.05) feed conversion ratios than other dietary treatments at 1 to 8 and 9 to 16 WOA, respectively. Thus, diets comprising 3,000 and 3,100 kcal of ME/kg were utilized more efficiently by the Pearl Gray guinea fowl pullets at 0 to 5 and 5 to 16 WOA, respectively. Also, these birds more efficiently utilized diets containing 24 and 17% CP at 0 to 8 and 9 to 16 WOA, respectively.
    Full-text · Article · Oct 2006 · Poultry Science
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