Effects of ambient temperature on sexual maturity in chickens

Heat shock protein B1 expression is associated with age at sexual maturity in Rhode Island Red and Punjab Red layers under heat stress

Heat shock proteins (Hsp) aid in protein folding and also to combat stress in all cellular organisms. HspB1 is a member of the small HSP family that has a significant role in thermo-tolerance. In this study, we aimed to determine the relationship (if any) between age at sexual maturity of layer poultry (Rhode Island Red and Punjab Red) and HspB1 expression both at mRNA and protein levels under heat stress. The mRNA expression of hspB1 was checked by real-time PCR. Delay in sexual maturity of the birds was found to be directly associated with the hspB1 mRNA expression in both the bird varieties under heat stress. No significant regression (association) of hspB1 mRNA expression with age at sexual maturity was observed in case of control, non-heat stressed birds. The serum levels of HspB1 were measured by indirect ELISA, using recombinant HspB1 that was expressed using pET-32b(+) vector in BL21(DE3) cells. Serum HspB1 concentration increased significantly (p ≤ 0.001) in heat-stressed birds as compared with control ones. A significant association was found between the increase in serum HspB1 concentration and delay in sexual maturity of all the birds under heat stress while no such association was found in control birds. In conclusion, HspB1 mRNA and protein expression were found to be associated with age at sexual maturity in Punjab Red and RIR layers under heat stress.

Effect of age on semen quality in naked neck and dwarf chicken under tropical climatic conditions

The present study was undertaken to elucidate the effect of age on semen quality of naked neck and dwarf chicken lines under tropical climatic conditions. Semen collected by abdominal massage at 4-week intervals from 24 to 48 weeks of age was evaluated for different semen quality parameters. Except sperm concentration and appearance, all other parameters were significantly (P < 0.05) affected by the age of the birds. The semen volume, motility, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide dye reduction test and percentage of live sperm were significantly (P < 0.05) lower at 24 weeks of age compared with 40 weeks of age. At 24 weeks of age the dead sperm percentage was significantly (P < 0.05) high and with advancing age it decreased. There was a significant difference (P < 0.05) between the gene lines for volume, appearance, motility, sperm concentration, and percentage of live and dead sperm. Except for sperm concentration, significant (P < 0.05) interaction between gene lines and age was observed in other parameters. In conclusion, semen quality was different between naked neck and dwarf line males and age affected semen quality of the gene lines studied in different manners.

Effects of hot environments and carbonated drinking water on bone characteristics of eight-week-old broiler chicks

Epiphyses of the femura from 8-week-old broiler chicks were examined for morphology using scanning electron microscopy and for elemental composition using energy dispersive x-ray microanalysis. Birds between the ages of 4 and 8 weeks were subjected to either 25 or 35 C environments and given tap or carbonated drinking water. The morphological appearance of the epiphyses was affected by the kind of drinking water but not the thermal environment. Elemental constituents, however, were affected by both environmental temperature and drinking water.

Effects of temperature on reproduction in guinea fowl

The effects of four temperature regimens on the onset and maintenance of semen and egg production, fertility, hatchability, and feed consumption by guinea fowl were examined. Temperatures of 26.7 and 21.1 C hastened the onset of egg and semen production in guinea fowl. However, egg and semen production rates of guineas exposed to ambient or 15.6 C minimum temperatures eventually increased to the level of those exposed to the higher temperatures. This suggests that it may be possible to initiate production by exposure to a warm environment and then reduce the environmental temperature after egg and semen production has been well established. There were no statistically significant differences in fertility or hatchability. Differences seen in feed conversion were mainly due to delayed onset of egg production in the lower temperature regimens. Thus, it appears that proper winter management of guinea breeders would involve exposure to a warm temperature for some period of time.

Reproductive performance of broiler breeders exposed to cycling high temperatures from 17 to 20 weeks of age

Forty male and 240 female broiler breeders were placed in cages within environmental chambers (20 males or 40 females per chamber) at 14 weeks of age. Chamber temperatures were maintained at 21.3 +/- 2.5 C, and relative humidity (RH) ranged from 40 to 50%. Ventilation rate was approximately 47.2 liters/sec per chamber, and light was provided from 0600 to 1800 hr. Feed was restricted daily according to industry recommendations, and water was provided ad libitum. From 17 to 20 weeks of age, control (C) chambers were kept at constant 21.0 +/- 1.4 C with 45 +/- 5% RH, and heat-treated (HT) chambers were cycled from 24.4 +/- 5.5 C (45 +/- 5% RH) during 1800 to 0800 hr to 36.0 +/- 2.8 C (15 +/- 5% RH) during 0800 to 1800 hr. Body weights were recorded at biweekly intervals. At 18 and 20 weeks of age, blood samples and rectal body temperatures were obtained randomly from five fasted birds per chamber at 0800 and 1400 hr. From 20 to 60 weeks of age, all birds were kept in individual cages in a conventional fan-ventilated house. Maximum temperature never exceeded 30 C, and average RH was 65.0%. Reproductive parameters were monitored and body weights were obtained at 4-week intervals. There were no significant treatment effects for body weight, body temperature, or differential leukocyte counts. Hematocrits were significantly lower for HT females than controls, and heat treatment did not result in consistent changes in plasma glucose or total proteins.(ABSTRACT TRUNCATED AT 250 WORDS)