. 2001. Effects of altering growth curve and age at photostimulation in female broiler breeders. 1. Reproductive development. Can. J. Anim. Sci. 81: 467-476. An experiment was conducted to evaluate the effect of differences in growth curve and age at photostimulation on carcass traits and ovarian morphology in broiler breeder hens at photostimulation and at sexual maturity. Pullets were grown on one of three growth curves STD (standard), LOW (150 g lighter than STD) and HIGH (150 g heavier than STD), and were photostimulated at either 19 wk of age (19WK) or 21 wk of age (21WK). Weekly blood samples were taken between photostimulation and sexual maturity for determination of estradiol-17β concentration. Twelve birds per interaction were processed at photostimulation for determination of carcass and reproductive morphology, followed by an additional 10 birds per interaction at sexual maturity. Unless otherwise stated, all significance was assessed at the P < 0.05 level.At photostimulation, the HIGH birds were larger and had more carcass lipid (7.44%) than the LOW birds (6.22%). By sexual maturity, carcass lipid as a percentage of BW was similar among the growth curve groups, as were the weights of most carcass parameters measured relative to BW. The large yellow follicle content of ovaries from LOW, STD, and HIGH birds were not different. Ovaries from HIGH birds had 48.2% of large yellow follicles arranged in multiple sets (large yellow follicles weighing within 1 g) compared to 29.5% in STD birds. Birds photostimulated earlier took longer to lay their first egg after photostimulation The profile of plasma estradiol-17β concentration of the 19WK birds appeared to increase more slowly than for the 21WK pullets. As plasma estradiol-17β concentration will increase at a regular rate once it begins to increase, the flatter summary profile of 19WK pullets may be indicative of a less-uniform response to photostimulation. Based on the BW growth curves used in this trial and data collected at photostimulation and sexual maturity, there was no advantage of early photostimulation, and ovarian morphology may be negatively affected by moderate increases in rearing growth curve. Key words:Broiler breeder, sexual maturity, ovarian morphology, growth curve, body weight Renema, R. A., Robinson, F. E. et Goerzen, P. R. 2001. Modification de la courbe de croissance et de l'âge à la photostimulation et leur incidence sur les pondeuses de poulets de chair : 1. Développement du système reproducteur. Can. J. Anim. Sci. 81: 467-476. Les auteurs ont tenté d'évaluer quels effets une modification de la courbe de croissance et de l'âge à la photostimulation pourrait avoir sur les paramètres de la carcasse et la morphologie des ovaires de pondeuses d'oeufs d'incubation au moment de la photostimulation et à maturité sexuelle. Les poulettes ont été réparties en trois groupes de courbe de croissance différente -soit STD (standard), FAIBLE (150 g de moins que STD) et ÉLEVÉE (150 g de plus que STD), puis photostimulées à l'âge de 19 (19 S) ou de 2...

2001. Effects of altering growth curve and age at photo-stimulation in female broiler breeders. 2. Egg production parameters. Can. J. Anim. Sci. 81: 477-486. An experiment was conducted to evaluate the effect of differences in growth curve and age at photostimulation on egg production parameters and carcass traits at 61 wk of age in broiler breeder hens. Pullets were grown on one of three growth curves: STD (standard), LOW (150 g lighter than STD) and HIGH (150 g heavier than STD), and photostimulated at either 19 wk of age (19WK) or 21 wk of age (21WK). The egg production and BW of 36 birds per interaction were individually monitored from photostimulation to 61 wk of age. Individual, daily egg production records were analyzed for total, settable, and defective egg production, rate of production, sequence length, and egg weight. Eggs were incubated for determination of fertility, hatchability, and embryonic mortality parameters. All birds remaining at 61 wk of age were processed for determination of carcass and reproductive morphology. Unless otherwise stated, all significance was assessed at the P < 0.05 level. Earlier photostimulation age advanced age at sexual maturity, but reduced the first egg weight. Weight of the first egg did not differ among growth curves. Settable egg production to 61 wk was not affected by growth curve, with settable egg production ranging from 157.5 eggs in STD birds to 164.1 eggs in HIGH birds. The HIGH birds produced more double-yolked eggs than LOW birds. Photostimulation age did not affect egg production. Eggs of the LOW birds underwent more embryonic loss during 1 to 7 d of incubation than either STD or HIGH eggs. At 61 wk of age, the shank length of birds on the LOW profile was less than that of the STD birds or the HIGH birds. Abdominal fatpad as a percentage of BW differed among growth curve treatments, comprising 4.46% (LOW), 5.06% (STD), and 5.69% (HIGH) of hen BW. Ovary weight of HIGH birds (44.7 g) was higher than that of LOW (39.2 g) or STD birds (37.7 g), but contained a similar number of large yellow follicles. The proportion of large yellow follicles in multiple follicle sets at 61 wk was correlated with unsettable egg number (r = 0.265), and was negatively associated with chick number (r =-0.269). There was no production advantage to early photostimulation, and egg and chick production were not negatively affected by a moderate raising or lowering of the growth curve.. 2001. Modification de la courbe de croissance et de l'âge à la photostimulation et leur incidence sur les pondeuses de poulets de chair : 2. Paramètres de ponte. Can. J. Anim. Sci. 81: 477-486. Les auteurs ont effectué une expérience pour déterminer quels effets une modification de la courbe de croissance et de l'âge à la photostimulation aurait sur les paramètres de ponte et la conformation de la carcasse des pondeuses d'oeufs d'incubation âgées de 61 semaines. Les poulettes ont été réparties en trois groupes de courbe de croissance différente-soit STD (standard), FAIBLE (150 g de moins que STD) et ÉL...

It has been shown in previous studies that fertility can be reduced in overweight broiler breeder (BB) flocks. In an effort to determine the effect of ad libitum feeding on the duration of fertility in BB hens, 60 52-wk-old Shaver Starbro hens were randomly assigned to one of two treatments, ad libitum feeding (F) or restricted feeding (R) to maintain breeder target weights. All hens were reared to 52 wk under conditions of feed restriction. All birds were weighed individually on a weekly basis. At the beginning of each of two 4-wk study periods (56 to 60 wk and 60 wk to 64 wk), all birds were inseminated on 2 consecutive d with 0.05 mL pooled BB semen. All eggs were weighed and placed in a forced air incubator the same day that they were laid. After 7 to 10 d of incubation, the eggs were broken out and scored macroscopically as fertile with live embryo, fertile with dead embryo (early embryonic death), or clear (assumed infertile). The duration of fertility was defined as the number of days from the day after the second insemination to the last fertile egg before two consecutive interfile eggs. Hen BW were significantly different between treatments within each of the two 4-wk studies. The mean BW of the F hens was 4,261 g in Study 1 and 4,448 g in Study 2. The BW of the R hens were 3,459 g in Study 1 and 3,565 g in Study 2. Egg production levels and average egg weight was not different between treatments in either study. In Study 1, the duration of fertility for the F hens (12.7 d) and the R hens (12.7 d) were not different. In Study 2, the durations of fertility were significantly higher (P < 0.05) in the R hens (12.7 d) than in the F hens (10.0 d). These results support the theory that overweight BB have a reduced duration of fertility that may contribute to a reduced fertility in artificially inseminated and naturally mated flocks.

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