Preservation of fowl semen in liquid nitrogen: Application to breeding programmes

1. A method of freezing semen of individual males was adapted for use under farm conditions using an automated freezing apparatus.

2. An insemination programme to produce high fertility and hatchability with semen which had been deep frozen for 2 months was devised.

3. Over 90% fertile eggs with a 90% hatch of all eggs set was obtained with frozen and thawed semen over a period from the 2nd to the 12th day after the first of four inseminations. The persistency of fertility was also tested and 93, 86.6 and 30.7% of the eggs were fertile during days 2 to 6, 2 to 8 and 9 to 15 after the last insemination.

4. Corresponding with the high fertility rate, chicks were produced by every hen that was inseminated and from every male whose semen was frozen and stored. The implications for future breeding practices of this successful result are discussed.     

Incubation of chicken eggs at altitude theoretical consideration of optimal gas composition

1. Eggs from sea level which are transferred to higher altitude for incubation require changes in incubator gas composition if they are to develop normally.

2. This not only requires compensation for the reduced O₂ partial pressure but, and of equal importance, recognition of the increased diffusivity of gases at altitude.

3. Equations are developed for predicting the required changes in O₂, CO₂ and water vapour composition of incubator gas at any altitude.     

Effects of high inclusion rates of salseed meal in the diet of chicks

1. Starter diets containing either maize or salseed meal to replace the maize were fed to chicks over a period of 2 weeks.

2. Growth rate, food intake, food utilisation and proportion of dietary nitrogen retained were much poorer in chicks receiving salseed meal.

3. The chicks receiving salseed meal developed pathological lesions in liver and kidney.

4. The red blood cell count, white blood cell count, haemoglobin concentration and packed cell volume of the chicks receiving salseed meal were lower than those of chicks receiving maize.

5. The apparent metabolisable energy value of salseed meal was determined as 6.83 MJ/kg.     

Dated rock engravings from wonderwerk cave, South Africa

Radiocarbon dates associated with engraved stones from sealed archeological deposits at Wonderwerk Cave in the northern Cape Province indicate that rock engraving in South Africa is at least 10,000 years old.