Lighting regimens and plasma LH and FSH in broiler breeders

Egg production by meat-type fowl is markedly inferior to that from commercial laying hens, and so, to assess the degree to which photorefractoriness might be a contributing factor, male- and female-line broiler breeders were maintained on 8-, 11- or 16-h photoperiods. In addition, to determine the age-related rate of change in response to an increment in photoperiod, other birds were transferred from 8- to 16-h photoperiods at 67 or 124 d. Blood samples were taken from all groups, except those on constant 11-h photoperiods, in both genotypes at 67, 69, 124 and 126 d, and from all lighting groups in the female line at 58 weeks (end of trial), and the plasma was assayed for plasma luteinising hormone (LH) and follicle stimulating hormone (FSH) concentration to investigate possible correlations with rate of sexual maturity, total egg numbers and terminal rates of lay. Prepubertal LH was consistently higher for the female line than for the male line, and higher for 16-h birds than for 8-h birds. At 69 and 126 d, LH values were not significantly different from those 2 d earlier for 8-h birds, but significantly reduced for 16-h birds. There was an increase in LH following photostimulation at 67 d, but no significant change after the 124-d light increase. There were no significant differences in FSH between the two genetic lines, nor any effect of photostimulation at 67 or 124 d. There was a tendency for FSH in 8-h birds to be higher than for 16-h birds, and this difference became significant for male-line birds at 67 d. At 58 weeks, LH was higher for constant 11- and 16-h birds and for birds photostimulated at 67 d than for constant 8-h controls or birds transferred from 8 to 16h at 124 d. Neither baseline nor photoinduced prepubertal changes in plasma LH nor FSH were found to be of value for predicting age at sexual maturity or subsequent rates of egg production. At 58 weeks, LH was not generally correlated with sexual maturity, total eggs or terminal rates of lay, however, there was a negative correlation with age at first egg in birds photostimulated at 124 d. It must be concluded that plasma LH and FSH concentrations are of minimal value to the broiler breeder industry for predicting the degree of photorefractoriness, the age at sexual maturity, or subsequent egg production.     

A comparison of three methods of food restriction of laying‐type pullets on growth and laying performance

1. Three methods of restricting the growth rate of pullets from 8 to 20 weeks of age were compared. They were: quantitative food restriction, a diet low in lysine and arginine and a low protein diet.

2. Food consumption up to 20 weeks of age was significantly reduced by all three treatments; mortality was increased and sexual maturity was delayed.

3. Greatest uniformity was observed amongst pullets fed on the low protein and the low lysine diets

4. By 70 weeks there were no significant differences in food conversion based on food consumed between 20 and 70 weeks of age, but based on consumption between 8 and 70 weeks the quantitatively restricted birds converted food most efficiently.

5. The most favourable method of restriction appeared to be the feeding of a low lysine or low protein diet, since rearing costs were low, and the performance of the pullets on these treatments was high.     

Cornification defect in the golden retriever: clinical, histopathological, ultrastructural and genetic characterisation

Veterinarians have recognised a nonpruritic skin disease in the Golden retriever breed characterised by excessive scaling of large, variably pigmented flakes of skin in otherwise healthy dogs. This prospective case series describes clinical, histopathological, ultrastructural and genetic features of this cornification defect in 17 affected dogs. The condition affects young dogs of either sex and is characterised by symmetrical, predominantly ventro-lateral scaling and hyperpigmentation of the trunk. Histopathological and ultrastructural changes of the stratum corneum are suggestive of delayed degradation of corneodesmosomes. A genetic aetiology is proposed and a single-trait autosomal recessive mode of inheritance discussed.     

Broiler breeders do not respond positively to photoperiodic increments given during the laying period

1. Broiler breeders were given a 3-h increase in photoperiod to 11 h at 20 week and then a series of increases to reach 16 or 17 h either immediately after the initial increment or in 30-min, 1- or 2-h increments starting at various ages after peak rate of lay. Controls were maintained on 11 h from 20 weeks. Changes in plasma LH concentration (after 7 d) were measured in birds that had been transferred to 11 or 16 h at 20 weeks and given further increases in photoperiod at 41 or 61 weeks of age. 2. Birds that were transferred to 16- or 17-h photoperiods, irrespective of when and how the maximum photoperiod was reached, had inferior rates of lay between 52 and 60 weeks of age to birds maintained on 11 h from 20 weeks. However, the 11-h birds laid more eggs on the floor and produced a larger number of cracked and dirty eggs, resulting in similar numbers of settable eggs. 3. Although transferring birds from 11- to 16-h photoperiods at 41 weeks of age significantly increased plasma LH concentration, there was no effect on egg production during the ensuing 12 d. None of the other increases in photoperiod significantly increased plasma LH, whether given at 41 or 61 weeks. 4. It is concluded in broiler breeders, that increases in photoperiod applied during the laying period, from 11 or 16 h, have little or no effect on LH secretion, do not compensate for age-related declines in egg production, and adversely affect rate of lay.     

A mechanistic, stochastic, population model of egg production

1. A mechanistic, stochastic egg production model is presented. Mean age at first egg may be predicted from the lighting programme applied during rearing, using the Bristol-Reading model (Lewis et al., 2002). 2. Rate of ovulation is determined by an amended version of the mathematical model of the ovulatory cycle, originally proposed by Etches and Schoch (1984). 3. Oviposition times are estimated from ovulation times. 4. Yolk, albumen and shell weights are calculated using allometric functions. 5. The model predicts egg production of a theoretical flock of laying hens for a full laying year, including random occurrences of double-yolked and soft-shelled eggs and internal ovulations.     

Model to predict age at sexual maturity in broiler breeders given a single increment in photoperiod

1. Data from 9 experiments in which broiler breeder pullets had been photostimulated at two or more ages were integrated to produce a model to predict age at 50% egg production following a single increase in photoperiod during rearing. 2. It was clear that the photosexual response in broiler breeders was strongly influenced by the feed allowance and hence the rate of prepubertal growth. Regressions for birds given either a constant photoperiod or a single increase indicated that mean age at 50% lay advances by 2 d for every 100-g increase in body weight at 20 weeks. 3. The general response of broiler breeders was similar to that previously reported for egg-type pullets, but with important changes in the ages at which the birds progressed from one physiological state to the next, depending on body weight. 4. Broiler breeders, unlike modern egg-type pullets, exhibit juvenile photorefractoriness and, depending on their body weight, require up to 20 weeks to dissipate this (faster growth allows quicker dissipation). As a consequence, a group of birds grown to a typical weight of 2.1 kg at 20 weeks do not start to be photoresponsive until about 10 weeks and are not uniformly responsive until 19 or 20 weeks. A transfer to a stimulatory photoperiod before a bird has dissipated photorefractoriness causes a delay of about 3 weeks in its sexual development, and this results in a bimodal distribution of ages at maturity when a flock is photostimulated between 10 and 20 weeks. 5. Once photosensitive, the response of broiler breeders to an increment in photoperiod is between 0.50 and 0.65 of that observed in ISA Brown egg-type pullets. However, a flock of broiler breeders with typical feed restriction starts to mature spontaneously under the influence of the initial photoperiod from about 25 weeks. 6. There is a difference of only 1 to 3 d in age at 50% egg production between a flock transferred to 11 or 12 h followed by further increases to 15 or 16 h and one increased abruptly to one of these photoperiods, and so this model can be used to predict maturity in a commercial flock of birds even though they are likely to be given a stepped, rather than a single, increase in photoperiod.     

Reaction of chlorpyrifos-methyl in aqueous hydrogen sulfide/bisulfide solutions

The kinetics of the reactions of chlorpyrifos-methyl, an organophosphorus insecticide, with hydrogen sulfide (H(2)S) and bisulfide (HS(-)) were determined in well-defined aqueous solutions. The resulting pseudo-first-order rate constant for chlorpyrifos-methyl with bisulfide yielded a second-order rate constant of (2.1 +/- 0.3) x 10(-3) M(-1) s(-1). The second-order rate constant for chlorpyrifos-methyl with hydrogen sulfide is significantly slower than the second-order rate constant with bisulfide. The contribution of H(2)S to the observed degradation rate constant of chlorpyrifos-methyl at concentrations of up to 4 mM H(2)S is not significant. The second-order rate constant of chlorpyrifos-methyl with H(2)S was too low to be measured in this study. The results indicate that HS(-) present at environmentally relevant concentrations may represent an important sink for phosphorothionate triesters in a coastal marine environment, while H(2)S reacts too slowly to be environmentally relevant (pH 6-9). Trichloropyridinol, the major product of hydrolysis of chlorpyrifos-methyl, is only a minor product of the reaction of chlorpyrifos-methyl with bisulfide; however, trichloropyridinol was found to be stable under the experimental conditions.     

INTEGRATED NUTRIENT MANAGEMENT FOR CABBAGE-BRINJAL-RED AMARANTH CROPPING PATTERN IN HOMESTEAD AREA

An experiment was conducted to study the effect of organic manure and chemical fertilizers on soil properties and vegetable crops in the cabbage-brinjal-red amaranth cropping pattern at the homestead in a Grey Terrace Soil (Aric Albaquept) of Bangladesh. There were eight treatments: poultry manure (PM) at 5 t ha^?1, cowdung (CD) at 10 t ha^?1, household waste (HW) at 10 t ha^?1, PM at 2.5 t ha^?1 + chemical fertilizers (CF), CD at 5 t ha^?1 + CF, HW at 5 t ha^?1 + CF, CF, and Control. The lone CF treatment indicates 100% chemical fertilizers and any manure + CF indicates supplementary or reduced rate of fertilizers. The PM at 2.5 t ha^?1 + CF treatment performed the best yield for cabbage and brinjal, and HW at 5 t ha^?1 + CF yielded the highest for red amaranth. The highest uptake of nitrogen, phosphorus, potassium, and sulfur was also found in the treatment that produced the highest yield. Bulk density, organic carbon, and nutrient availability in soil as determined after two-crop cycles were improved due to the applications of manure.