A total of 2000 Hubbard Classic females and 180 males (male to female ratio 1:11) close to standard body weights were selected and managed separately in the same shed. The objective of this experiment was to study the effects of egg size (small, medium and large) at mid (45 weeks) production cycle and flock age (30, 45 and 60 weeks old) on hatching egg weight loss, fertility, hatchability traits, chick weight and chick yield in a commercial Hubbard Classic broiler breeder flock. The results showed that minimum egg weight loss (P ≤ 0.05) was recorded in large egg size group at different incubation periods and egg weight losses decreased with advancing the age of breeder hens. Maximum fertility and hatchability (P ≤ 0.05) was noticed in small egg size group, followed by medium and large egg size groups. However, maximum embryonic mortality (P ≤ 0.05) during incubation and higher percentage of infertile eggs was recorded in large size egg group, followed by medium and small egg size groups. Low fertility, hatchability was recorded (P ≤ 0.05) in older hen at the age of 60 weeks. The chick weight and chick length were amplified (P ≤ 0.05) with increasing the egg size. However, egg size was not influenced (P ≥ 0.05) on chick yield. The chick weight, chick yield and chick length were improved (P ≤ 0.05) with advancing age of broiler breeder.

A study was conducted to evaluate enzyme and probiotic feed supplements as alternative feed additives to alleviate the problems associated with the withdrawal of antibiotics from layer diet. A total of 180 Hy-Line W-98 hens, 40 weeks old, were assigned into four treatment groups so that there were 45 laying hens in each group. Four dietary treatments were randomly assigned to the four groups of hens. Hens in Group 1 were fed basal diet only (negative control), Group 2 was fed basal diet ' antibiotic at a level of 2.0 g/kg (positive control), Group 3 was fed basal diet ' multi-enzyme at a level of 2.0 g/kg (ES) and Group 4 was fed basal diet ' multi-species probiotic at a level of 0.5 g/kg (PS). The results showed that addition of either enzyme or probiotic supplementation to the basal diet significantly increased the egg production, egg weight and egg mass of hens than the negative control group. There was no significant difference in feed intake among treatments, although the feed conversion improved with the addition of antibiotic, enzyme and probiotic than the negative control. Over the 70-day trial period, weight gain was higher than the negative control for birds fed the diet containing probiotic. There was no significant effect on mortality during the study. Haugh unit score was significantly increased in the groups fed the ES and PS diets when compared with negative control group. Egg shape index, specific gravity, yolk index, shell weight, shell thickness and damaged eggs did not differ significantly among the laying hens of all dietary groups. High-density lipoprotein-cholesterol was significantly increased by probiotic supplementation compared with other dietary groups. Dietary treatments did not influence eosinophils and monocytes, increased lymphocyte and decreased heterophil and H:L ratio. The geometric means haemagglutination inhibition titres of birds fed on diets containing antibiotic, enzyme and probiotic supplementation were higher from 28 to 70 days than that of negative control. It may be concluded that the supplementation of enzyme and probiotic in layer diets did not appear to cause any adverse effects on egg production, egg quality and immunity compared with the negative control laying hens and non-antibiotic feed additives can be used as alternative. Moreover, the dietary supplementation of probiotic may lead to the development of low-cholesterol chicken eggs as demanded by health-conscious consumers.

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A total of 2001 un-sexed day-old chicks of each Desi, Fayoumi and Rhode Island Red (RIR) breeds were obtained from hatchery of Poultry Research Institute, Rawalpindi. The birds were maintained on deep litter system for a period of 72 weeks. In floor pens, each breed was reared separately in a single pen until seven weeks of age when 2001 birds were randomly distributed between pens, with 21 to 24 birds of the same breed per pen (2.00 to 2.50 ft 2 /bird). The results revealed that the average day-old weight was highest in RIR, intermediate in Desi and lowest in Fayoumi. The RIR breed consumed more feed and gained maximum (p B0.05) weight than those of Desi and Fayoumi breeds at all ages of growing phase. The feed conversion was poor (pB0.05) in Desi and better in RIR breed. Desi and Fayoumi chicks had lowest (p B0.05) mortality than RIR breed. The breast and thigh meat composition was found non-significant (p 0.05) amongst three breeds. The age of sexual maturity was lowest in Fayoumi followed by RIR and Desi. The highest egg production was obtained by RIR with 41% followed by Fayoumi (36%) and the Desi breed (29%). The egg weight and egg mass were highest (p B0.05) in RIR, but non-significant (p 0.05) differences were found between Fayoumi and Desi breeds. The internal egg quality parameters including yolk weight, albumen weight, yolk plus albumin weight and albumin height were significantly higher in RIR breed than those of Fayoumi and Desi breeds. However, shell and yolk thickness did not differ significantly amongst three breeds. There was non-significant (p 0.05) difference in blood glucose, triglyceride, cholesterol, calcium, protein, uric acid and alkaline phosphatase values amongst three breeds. There was non-significant (p 0.05) difference in haematological values among all breeds. The total erythrocyte count, haemoglobin and packed cell volume increased with the advancement of age. However, erythrocyte sedimentation rate, mean corpuscular volume and mean corpuscular haemoglobin values decreased gradually with the advancement of age. It may be concluded that overall RIR chickens performed better than Fayoumi and Desi chickens. However, early age of sexual maturity was noticed in Fayoumi chickens, and low mortality was observed in Desi chickens.

A total of 225 hens (18 weeks of age) of each Rhode Island Red male x Fayoumi female (RIFI), Fayoumi male x Rhode Island Red female (FIRI) and White Leghorn male x FIRI female (RLH) were maintained on deep litter system for a period of 72 weeks of age. In floor pens, each crossbred chicken was randomly distributed between pens, with 21 to 24 birds of the same breed per pen (2.00 to 2.50 ft 2 /bird). The results revealed that the age of sexual maturity was lowest in RIFI followed by FIRI and RLH chickens. The highest egg production was obtained by three-way crossbred chickens (RLH) as compared with two-way crossbred chickens (RIFI and FIRI). The highest egg weight was observed in RLH than those of FIRI and RIFI crossbred chickens. The internal egg quality parameters included yolk weight, albumen weight, yolk + albumen weight and albumen height were same in all crossbred chickens. There was non-significant (P>0.05) difference in blood glucose, triglyceride, cholesterol, calcium, protein, uric acid and ALP values among all crossbred chickens. It may be concluded that three-way crossbred chickens (RLH) showed better egg traits than two-way crossbred chickens (RIFI and FIRI) with lower mortality. The RIFI crossbred chickens achieved sexual maturity earlier than both FIRI and RLH crossbred chickens with lower egg traits.

BackgroundResearch into energy balance and growth has infrequently considered genetic sex, yet there is sexual dimorphism for growth across the animal kingdom. We test the hypothesis that in the chicken, there is a sex difference in arcuate nucleus neuropeptide gene expression, since previous research indicates hypothalamic AGRP expression is correlated with growth potential and that males grow faster than females. Because growth has been heavily selected in some chicken lines, food restriction is necessary to improve reproductive performance and welfare, but this increases hunger. Dietary dilution has been proposed to ameliorate this undesirable effect. We aimed to distinguish the effects of gut fullness from nutritional feedback on hypothalamic gene expression and its interaction with sex.MethodsTwelve-week-old male and female fast-growing chickens were either released from restriction and fed ad libitum or a restricted diet plus 15% w/w ispaghula husk, a non-nutritive bulking agent, for 2 days. A control group remained on quantitative restriction. Hypothalamic arcuate nucleus neuropeptides were measured using real-time PCR. To confirm observed sex differences, the experiment was repeated using only ad libitum and restricted fed fast-growing chickens and in a genetically distinct breed of ad libitum fed male and female chickens. Linear mixed models (Genstat 18) were used for statistical analysis with transformation where appropriate.ResultsThere were pronounced sex differences: expression of the orexigenic genes AGRP (P < 0.001) and NPY (P < 0.002) was higher in males of the fast-growing strain. In genetically distinct chickens, males had higher AGRP mRNA (P = 0.002) expression than females, suggesting sex difference was not restricted to a fast-growing strain. AGRP (P < 0.001) expression was significantly decreased in ad libitum fed birds but was high and indistinguishable between birds on a quantitative versus qualitative restricted diet. Inversely, gene expression of the anorectic genes POMC and CART was significantly higher in ad libitum fed birds but no consistent sex differences were observed.ConclusionExpression of orexigenic peptides in the avian hypothalamus are significantly different between sexes. This could be useful starting point of investigating further if AGRP is an indicator of growth potential. Results also demonstrate that gut fill alone does not reduce orexigenic gene expression.Electronic supplementary materialThe online version of this article (10.1186/s13293-018-0178-6) contains supplementary material, which is available to authorized users.

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