British Poultry Science

Payne, L. N.

doi: 10.1080/00071669408417666pmid: 8199888

Abstract 1. Poultry disease research in the UK began recognisably in the 1920s, in consequence of the development of a national poultry industry of economic importance. 2. Increasing disease problems during the 1930s revealed the need for more research, resulting notably in the growth of the Poultry Department of the Central Veterinary Laboratory and the establishment of Houghton Poultry Research Station. 3. Continued growth of the egg industry and the introduction of the broiler industry in the 1950s stimulated increased disease research, much of it publicly funded, during the following two decades. 4. Changing government attitudes to agricultural research in the 1980s brought about far‐reaching changes to the funding, organisation, nature and amount of disease research conducted. Arrangements for such research continue to evolve.

Lewis, P. D.; Perry, G. C.; Morris, T. R.; Follett, B. K.

doi: 10.1080/00071669408417667pmid: 8199887

Abstract 1. Brown egg laying pullets were transferred from an 8‐h photoperiod to an 8‐, 10‐, 13‐ or 16‐h photoperiod at 6, 9, 12, 15, 18 or 20–3 weeks of age. Plasma luteinising hormone (LH) concentrations were measured at transfer and 7 and 14 d afterwards. 2. Significant increases in plasma LH occurred following light stimulations at 6, 9 and 12 weeks of age. 3. Changes in LH concentration 7 d after a light increase from 8 h to 8, 10, 13, 16 h were highly correlated with photoperiod length at 9 and 12 weeks of age. 4. Changes in LH were generally poorly correlated with age at sexual maturity, although the reduced influence on age at first egg of a light increase given close to sexual maturity was reflected in minimal LH responses at 18 and 20.3 weeks.

Wolf, J.; Knížetová, H.

doi: 10.1080/00071669408417668pmid: 8199889

Abstract 1. Three sire lines of Pekin duck, three dam lines and 9 crosses between these two groups were tested in replicated tests from 1987 to 1991. Body weight at the age of 7 weeks (n = 5189), carcase percentage, percentage of abdominal fat and thickness of breast muscles were recorded (n = 1432 for carcase traits). 2. The data were analysed by linear models. All models contained the factors test and sex. When analysing only crosses, general and specific combining abilities (GCA and SCA respectively) were included as well as their interactions with the test. Using the complete data set (lines and crosses), direct genetic and heterotic effects were considered. 3. The factors test and sex were significant in both data sets for all traits. 4. For body weight, all genetic factors were significant. The average heterosis was 65 g ± 9 g (2.2%); the highest observed heterosis was 7.7%. 5. For carcase percentage, the heterosis was always negative (up to — 2.1%), whereas in abdominal fat, a desirable negative heterosis was observed only in one cross. No significant heterotic or combining ability effects were observed in the thickness of breast muscles. 6. Significant interactions between at least one genetic factor and test were found in all traits. 7. The relative importance of GCA and SCA, possible sources of confounding estimates of genetic effects, the importance of heterotic effects and genotype × environment interactions are discussed.

Afraz, F.; Yamamoto, Y.; Okada, I.

doi: 10.1080/00071669408417669pmid: 8199890

Abstract 1. Two‐way selection for delayed‐type hypersensitivity wattle reaction (DWR) competence to BCG antigen was carried out over 4 generations, using a flock of White Leghorn chickens. DWR was measured by intradermal injection of BCG into the wattle of chickens. 2. Selection for DWR was effective. The generation means of average selection differential, selection response and realized heritability were 1–15 mm, 0–77 mm and 0–70 respectively. Correlated responses were found in body weight, egg weight and hatchability. In all of these traits, the L line (selected for low wattle reaction) showed higher values than the H line (high reaction). 3. Specific trends in gene frequencies were observed at the major histocompatibility B and alkaline phosphatase Akp loci. 4. Significant line differences were found in graft‐versus‐host reaction competence and Marek's disease resistance. In both characters, the L line was higher than the H line. No line differences were found in phytohaemagglutinin reponse, phagocytic activity or immune responses.

Tai, C.; Poivey, J. P.; Rouvier, R.

doi: 10.1080/00071669408417670pmid: 8199891

Abstract 1. Fertility traits in 348 Brown Tsaiya female ducks were analysed following intergeneric crossbreeding by artificial insemination (AI) with pooled Muscovy semen. The females descended from 18 sires and 107 dams. At 50 weeks of age, the ducks were intra‐vaginally inseminated once with 0.03 ml of pooled Muscovy semen. Subsequently eggs were collected for 15 d and set for incubation up to candling 10 d later. 2. Average fertility decreased from 87% at day 2 after AI to 53% at day 6 and less than 7% from day 10 onwards. 3. The best criterion of selection for duration of fertility seems to be the number of fertile eggs from 2nd day up to the 15th day after AI. Heritability estimates for this trait were A2 = 0.29 ± 0.18., h2 D = 0.38 ± 0.22.

Remignon, H.; Lefaucheur, L.; Blum, J. C.; Ricard, F. H.

doi: 10.1080/00071669408417671pmid: 8199892

Abstract 1. Histochemical (fibre type distribution and areas) and biochemical (myosin isoforms) characteristics of three muscles, M. anterior latissimus dorsi, M. pectoralis major and M. sartorius, were compared among male chickens of two lines at 11 and 55 weeks of age. 2. The lines were derived from a divergent selection based on growth rate. Cockerels from the Fast Growing Line (FGL) were 2‐3 times heavier than those from the Slow Growing line (SGL) when 11 weeks old and 1–7 times at 55 weeks of age. The latter age was chosen as representative of the adult stage and the 11‐week age because, at this time, FGL cocks weighed as much as SGL cockerels at 55 weeks. 3. At both ages, the two lines showed similar fibre type distributions, but the total number in the ALD muscle, and the size (cross‐sectional areas) of fibres in each muscle were higher in the FGL compared with the SGL (14–6% and 33% more at 11 and 55 weeks of age respectively in favour of the FGL birds). 4. The two lines displayed similar myosin isoform patterns when adult muscles were compared (55 weeks). They differed slightly at 11 weeks of age, muscle differentiation being completed only in the FGL. 5 Comparisons of the two lines at the same live weight (i.e. FGL cockerels at 11 weeks of age and SGL cockerels at 55 weeks) showed larger muscle fibres in the SGL and no difference in the isomyosin patterns.

Raj, A. B. M.

doi: 10.1080/00071669408417672pmid: N/A

Abstract 1. Three hundred and sixty turkeys comprising 16 week‐old stags (medium stags), 22 week‐old stags (large stags) or 52 week‐old hens (hens) were stunned with either argon‐induced anoxia, 30% carbon dioxide in argon with 2% residual oxygen (gas mixture) or electric current and the carcases were processed under commercial conditions. The carcases were chilled at either 16°C or 3°C using a commercial immersion chiller and the carcases were held in a cold room (3°C). 2. Breast muscles (pectoralis major) were filleted at either 2, 3, 5 or 18 h post‐mortem, and pH and muscle temperature were measured at the time of filleting for the medium and large stags. The breast fillets removed soon after killing were stored at 3°C until transported to the laboratory. 3. All the breast fillets were cooked to an internal muscle temperature of 85°C and their texture was measured instrumentally. The fillets were weighed before and after cooking to determine the proportional cooking loss. 4. The results showed that, for electrical stunning, the rate of pH fall soon after killing differed between the bird types, and it resulted in a variable texture in the breast meat when filleting was performed soon after killing. The medium stags had a relatively slower rate of pH fall and filleting them soon after killing resulted in tougher breast meat. 5. By contrast, in all the three bird types, gas stunning resulted in a rapid pH fall soon after killing and produced tender breast meat at all the filleting times tested. 6. The cooking loss was higher in the large stags than in the medium stags or hens. 7. Stunning turkeys by anoxia or 30% carbon dioxide in argon would enable filleting to be performed soon after killing, and produce less variable‐and more tender breast meat.

Karasawa, Y.; Ono, T.; Koh, K.

doi: 10.1080/00071669408417673pmid: 8199893

Abstract 1. The relationship of the decreased caecal urease activity by dietary penicillin to nitrogen utilisation was assessed in chickens fed a low protein diet plus urea. 2. Dietary penicillin at 20 and 100 mg/kg decreased anaerobic bacteria counts, urease activity and ammonia concentration in caecal contents (P< 0.05, except for ammonia in the case of the 100 mg/kg penicillin diet). 3. The 20 mg/kg penicillin diets significantly increased the excretion of urea and total nitrogen (P < 0.05) and decreased ammonia excretion, and significantly reduced nitrogen retention (P < 0.05). The 100 mg/kg penicillin diet also resulted in similar but not significant changes, which tended to be less than those by the 20 mg/kg penicillin diet. 4. Ammonia, urea, glutamine and uric acid concentrations in blood, liver and kidney were unchanged by dietary penicillin. 5. It is concluded that caecal ammonia production from urea was closely correlated with nitrogen utilisation in chickens fed a low protein diet plus urea.

Jones, G. P. D.

doi: 10.1080/00071669408417674pmid: 8199894

Abstract 1. An experiment using respiration calorimetry was performed to examine the energy and nitrogen metabolism of 2 strains of male broilers grown at 3 environmental temperatures; the results were then related to the susceptibility of the strains to the ascites syndrome. 2. Broilers selected for food conversion efficiency were less responsive to environmental temperature than were broilers selected principally for increased weight gain. 3. The susceptibility to ascites of broilers selected for food conversion efficiency may be the result not of a genetic incapacity to use oxygen but of the ability of the bird to maintain growth rate in adverse thermal environments.

Scaife, J. R.; Moyo, J.; Galbraith, H.; Michie, W.; Campbell, V.

doi: 10.1080/00071669408417675pmid: 8199880

Abstract 1. A study was undertaken to examine the effect of supplementation of diets with fats of different chain length and degree of unsaturation on the performance, carcase characteristics and tissue fatty acid composition of broilers. 2. Three hundred and sixty 19‐day‐old female broilers were fed on diets containing supplemental fat/oil (50 g/kg) in the form of beef tallow (BT) (diet T‐T), soyabean oil (SBO) (diet S‐S), rapeseed oil (RSO) (diet R‐R), marine oil (MO) (diet M‐M) or binary mixtures (0.5:0.5 w/w) of these lipids (diets T‐S, T‐R, T‐M, S‐R, S‐M, and R‐M) to 54 d of age. Food intake, live weight, plucked weight and the lipid concentration and fatty acid composition of abdominal fat pad, liver and breast muscle were measured. 3. Food intake, plucked weight and live weight were greatest for diet T‐T and lowest for diet R‐R. Food conversion ratio was poorest for birds fed on diets containing BT. Lipid concentration in abdominal fat pad was significantly higher in birds fed on diets containing SBO. liver lipid concentration was significantly reduced by diets containing RSO. 4. Abdominal fat pad fatty acid profile was most readily altered by dietary fatty acids. There was a strong correlation between dietary fatty acid composition and tissue fatty acid composition for all fatty acids except C14:0, C20:0, C20: 2n‐6 and C20: 4n‐6. The tissue P/S ratio ranged from 0.40 for diet T‐T to 1.40 for diet S‐S. The n‐6/n‐3 ratio was significantly increased by the inclusion of SBO and decreased by the inclusion of MO. 5. Liver fatty acid profile was least modified by dietary fatty acids. There was an inverse relationship between liver and dietary C20:4n‐6 concentration. Tissue C18:2n‐6 and C20:4n‐6 were highly correlated, suggesting significant interconversion by ?‐6 desaturase in this tissue. The n‐6/n‐3 ratio was significantly increased by inclusion of SBO and significantly decreased by the inclusion of MO. 6. In breast muscle MO‐based diets increased the proportion of n‐3 PUFA at the expense of n‐6 PUFA. The tissue concentrations of C18:ln‐9, C18:2n‐6, C20:ln‐9, C20:5n‐3, C22:5n‐3 and C22:6n‐3 were strongly correlated with dietary fatty acid composition. Muscle and diet P/S and n‐6/n‐3 ratios were highly correlated.