Effect of different patterns of food restriction from different ages on growth and efficiency of broilers

1. The effect of restricted feeding on performance and carcass characteristics of broilers was determined in three experiments.

2. In the first experiment, removal of food for 8 h/d from 42 to 56 d of age significantly improved food conversion efficiency of broilers on deep litter. Removal of food for 16 h/d or on alternate days tended to cause slower growth and also improved conversion efficiency.

3. In the second experiment, denial of food for 8 h/d did not significantly affect either growth rate or conversion efficiency of caged broilers. Denial of food on alternate days, from 28 d of age, depressed food intake and growth rate. Food restriction decreased dressing percentage regardless of the age of introduction. With 32, 40 or 48 h food denial each 72 h there was a large depression in growth rate and dressing percentage. Carcass dry matter was also less, indicating less carcass fat, when food was denied for 48 h each 72 h.

4. In the third experiment, growth rate of broilers on deep litter was significantly improved by denying food for 8 h/d from 28 d of age, and was significantly depressed by food denial on alternate days. This depression was significantly more severe if restriction started at 28 d rather than at 42 d of age. Conversion efficiency was not significantly improved by denial for 8 h/d.

5. In the last two experiments conversion efficiency was much worse in severe restriction.     

Lymphocyte transformation test in the calf]

Studies into the effects of the environment on health and performance of agricultural animals are of clear-cut relevance to farming practice. The theoretical and practical importance of lymphocyte transformation to any assessment of immunological reactivity under defined environmental conditions, therefore, is reported in this paper. Communicated is methodical experience obtained from isolation of lymphocytes from peripheral blood of calves, lymphocyte culturing, and morphological evaluation of lymphocyte transformation. Views are given on the suitability of the lymphocyte transformation test. The following results have been obtained: Centrifugation of defibrinated blood, using "Visotrast-370", is recommended for lymphocyte isolation. Morphological evaluation will ensure a high degree of precision when 1 x 10(6) cells in one millilitre culturing fluid are to be cultured over three days, the culturing fluid consisting of 20 per cent of autologous serum and 80 per cent of Eagle medium, antibiotics, and a portion of 1-vol.% of phytohaemagglutinin (Wellcome). The lymphocyte transformation test, for its methodical accuracy, is good enough to detect and identify environmental effects on immunological reactivity of calf. It is likely to reflect the immunological response to an antigen application.     

Responses of immune and nonimmune adult rhesus macaques (Macaca mulatta) to adenovirus SV-20.

Adenovirus SV-20 (ASV-20) was inoculated subcutaneously into adult rhesus macaques (Macaca mulatta), and various immunologic parameters were studied. Similar changes were observed in macaques that had anti-ASV-20 serum-neutralizing antibodies prior to inoculation and in those lacking detectable antibodies. There were absolute decreases in numbers of peripheral blood lymphocytes (PBL), erythrocyte-rosetting lymphocytes, complement-receptor lymphocytes, and Fc-receptor lymphocytes. These changes were most significant (P less than 0.05) on postinoculation days (PID) 3 and 7. Mitogenic responsiveness to concanavalin A, phytohemagglutinin, and pokeweed mitogen in cultured PBL from immune and nonimmune macaques was depressed on PID 3, 7, and 14. Ultraviolet-inactivated ASV-20 caused moderate suppression of phytohemagglutinin-induced mitogenesis when viral particles and lectin were added simultaneously to PBL cultures. Plasma cortisol (hydrocortisone) values were not significantly altered following inoculation of ASV-20. High titers of anti-ASV-20 antibody developed by PID 7 in nonimmune macaques, and previously immune macaques showed a booster effect in the same time period. Antibody titers were still increased 120 days after inoculation. There was no clinical evidence of an adverse effect of ASV-20 infection in these macaques.     

Longitudinal studies of naturally acquired Brucella abortus infection in sheep.

Naturally acquired Brucella abortus infections were studied during consecutive pregnancies in eight sheep and in their lambs over a period of 40 months to evaluate epizootiologic aspects of natural infection in sheep. Brucella abortus was isolated from the ewes following 16 of 26 natural terminations of pregnancy: from 5 of 6 ewes in the first year, from six of eight ewes in the second year, from two of six ewes in the third year, and from three of six ewes in the fourth year. Vaginal swab samples and milk samples were the most consistent source of the brucella organisms. Brucella abortus was isolated from three ewes when standard tube test seroagglutination titers were less than 1:100. In contrast, results of supplemental tests (card, 2-mercaptoethanol, complement-fixation, and Rivanol) remained positive during the study. During the 40 months, B abortus was isolated from 4 of 4 aborted fetuses, 2 of 5 stillborn lambs, 10 of 37 living lambs, and as an indicator of continuing infection, from 6 of 12 lambs born during the fourth year. Although B abortus has a definite host preference for cattle, this study demonstrated that under appropriate management conditions, sheep may be naturally infected and may remain infected for more than 40 months. Epizootiologic evaluation of all factors, including husbandry practices and exposure potential, should be utilized in determining the need to test other species that may have been exposed to cattle infected with B abortus.