The photoperiodic effect of ahemeral light‐dark cycles which entrain circadian rhythms

1. A 27‐h cycle of light and dark provides a greater gonadotrophic stimulus to the laying fowl, as judged by sexual maturity and rate of lay, than a 24‐h cycle incorporating the same photoperiod.

2. An hypothesis put forward to account for these effects states that Effective Photoperiod equals p + c – b, where p = actual photoperiod, c = cycle length and b = the period of the endogenous biological clock.

3. Two experiments designed to test this hypothesis have yielded results which are consistent with it.

4. A poultryman who uses an ahemeral cycle to alter egg weight or shell thickness and then wishes to transfer his flock back to a 24‐h cycle should calculate the difference between the two cycle lengths and then add this quantity to the prevailing photoperiod to find the appropriate amount of light to be used in the 24‐h cycle.     

The action of sulphanilamide on shell deposition

1. The action of sulphanilamide on egg shell deposition has been studied in the domestic fowl. The length of time that eggs remain in the shell gland was measured; the relative thickness and protoporphyrin pigment concentration for egg shells removed from the shell gland were determined; egg shell structure was examined using a replica technique.

2. Sulphanilamide appeared to act mainly by reducing the rate of shell deposition, time spent in the shell gland was unaffected.

3. The thickness of shell components was reduced in a roughly proportional manner in thin shells produced during sulphanilamide treatment.

4. It is proposed that other thin shells in which the component layers are all reduced to a similar extent are also the result of a decreased deposition rate.     

Sire × hatch interaction effects and pen effects in progeny testing broiler males for growth rate

1. Pen effects and sire x hatch interaction effects on growth rate to 8 weeks of age were estimated from family and progeny test data obtained from the application of two commercial breeding programmes for growth rate to broilers.

2. The following variance components were obtained: σ²(pen) = 255 g², σ²(sire) = 1 260 g², σ²(sire × hatch) = 1 997 g²,σ²(residual) = 19 708 g².

3. It is concluded that the effectiveness of progeny testing for growth rate in broilers is severely restricted by sire x hatch interaction effects.     

The use of n‐paraffin‐grown yeast as the main source of protein in diets for chicks

1. n‐Paraffin‐grown yeast and a mixture of soyabean meal and fish meal were compared in the net protein utilisation (NPU) test, and as protein supplements in diets for broilers up to 4 weeks of age.

2. The difference between the NPU values, 0.66 for yeast and 0.80 for the soyabean meal and fish meal mixture, could largely be attributed to the high nucleic acid content of the yeast.

3. Chicks given the diet containing yeast (190 g/kg) did not grow as rapidly as those given the soyabean meal and fish meal reference diet, and the reduced growth could only partly be explained by a marginal deficiency of methionine.

4. Food conversion efficiency with the yeast diet was improved by maize oil while responses to α‐tocopheryl acetate and sodium selenite were inconsistent.

5. Chicks grew well when yeast replaced fish meal in the mixture of soyabean meal and fish meal, and when fish meal (194 g/kg diet) was the sole protein supplement.     

Comparisons of frequencies and egg shell characteristics of broken and intact eggs within diverse populations of chickens

1. Differences were found among eight populations of White Plymouth Rock pullets in the frequency of broken eggs.

2. The shells of such eggs were thinner than those of intact eggs in seven of the populations.

3. The number of defective eggs, the specific gravity of the eggs, and the percentage hen‐day egg production of normal eggs were significantly correlated within populations with the incidence of broken eggs.

4. No significant correlations were found within populations between the incidence of egg breakage and either egg weight, body weight, or shank length.     

Estimating adrenal cortical function in dogs with ACTH.

The peripheral blood response to intramuscular injection of 10 units ACTH in dogs was investigated because no experimental evidence for the standardization of this procedure for clinical use was available. Following the injection of ACTH in sodium chloride solution, neutrophilia, monocytosis, eosinopenia, and lymphopenia occurred. With the exception of eosinopenia, the greatest change in the concentration of each cell type in peripheral blood occurred between 2 and 4 hours post injection. The maximum change in eosinophil numbers occurred between 4 and 6 hours post injection. When all cell types were considered, 4 hours post injection was the most suitable time to measure the cellular response in peripheral blood in dogs which respond to ACTH. The data indicate that change in the ratio of neutrophils to lymphocytes (N/L) prior to and at 2 to 4 hours after ACTH injection in normal dogs was a sensitive index of response and occured sooner than eosinopenia. The extent of change in the N/L ratio was such that accuracy in interpretation could be obtained by counting as few as 40 cells.     

The effects of low voltage current on healing of thermal third degree wounds.

Bilateral third degree burns were created on the flanks of eight miniature swine. Each animal had one side treated daily with low intensity direct (LIDC) of 400 microamperes (muA) by contact electrode for 2 hours morning and afternoon until healing occurred. The polarity of the electrode was negative in 4 pigs and positive in 4 pigs. One group of 4 pigs had the eschar surgically removed 24 hours post burn. Weekly biopsies and cultures were taken of treated and control wounds. Results indicated: local treatment of 400 muA LIDC did not hasten or delay healing of thermal third degree burns; escharectomy hastened wound healing by 10 days, and superficial proteus infection occurred in 80% of all wounds.     

Treatment of the repeat breeder cow syndrome in Kenya

Summary One hundred repeat breeder dairy cows have been studied in detail. Although clinically 60 per cent of them were normal bacteria were isolated from the uteri of the majority (90 per cent). Thirty per cent of these isolates were mixed.Intra-uterine infusion of the uteri with diluted Lugol's Iodine solution, supplemented in a few cases by antibiotic therapy, resulted in a 62 per cent conception rate compared with 26 per cent in the control group. It is concluded that dilute Lugol's Iodine is a useful treatment for repeat breeder cows under conditions similar to those described.

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Tratamiento Del Sindrome De Vacas Repetidoras En Kenya

Resumen Se estudíaron en detalle 100 vacas repetidoras destinadas a la producción de leche, en Kenya. Aunque el 60 por ciento de ellas parecía normal clinicamente, se aislaron bacterias del útero de la mayoría (90 por ciento). El 30 por ciento de los aislamientos fue mixto.La infusión intrauterina de una solución diluída de Lugol, combinada en algunos casos con antibióticos, resultó en una proporción del 62 por ciento de concepciones, comparada con el 26 por ciento del grupo control. Se concluye, que la solución de Lugol diluída es útil para el tratamiento del síndrome de vacas repetidoras, bajo condiciones similares a las aquí descritas.

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Traitement Du Syndrome De L'Accouplement Repete Chez La Vache Au Kenya

Résumé Cent vaches laitières ont été examinées avec soin. Bien que 60 p. 100 d'entre elles aient été considérées comme normales, des germes ont été isolés de l'utérus de la majorité d'entre elles (90 p. 100). Dans 30 p. 100 des cas, la population microbienne était mixte.Des injections intra-utérines d'une solution diluée de Lugol accompagnée dans quelques cas par de l'antibiothérapie ont fait que le groupe traité à un taux de fécondité de 62 p. 100 contre 26 p. 100 dans le groupe témoin. Les auteurs concluent que la solution iodée de Lugol constitute un traitement utile chez les vaches contre ce syndrome, dans les conditions semblables à celles décrites.