South African Journal of Animal Science

The identification of low-producing hens in egg production systems using objective methods

2025-03-18T11:16:10+00:00

In commercial egg production, hen productivity declines over time, leading to flock disposal for economic reasons at 72–80 weeks of age. Identifying and removing low-producing hens can enhance economic sustainability by maximising the performance of high-performing hens and conserving feed resources. Additionally, more space per productive hen can improve overall welfare. Current methods for identifying low-producing hens are subjective and challenging, particularly in large operations. Thus, objective culling techniques are needed. This study evaluated hen productivity by examining physiological and thermal changes. We correlated body colour and temperature with productivity criteria such as egg production and the feed conversion ratio (FCR). Twelve white Lohmann LSL and 12 Lohmann Brown hens of 83–100 weeks of age were included in the trial, which was conducted over an 18-week period. Hens with an egg production rate below 60% or FCR above 3 were deemed lowproducing. Weekly thermal imaging captured head and foot temperatures, while spectrophotometry and digital imaging recorded the colour of the feet, combs, and beaks. A significant correlation between productivity and RGB values was found in both hybrid lines. These findings suggest the potential practical application of these techniques in poultry houses, especially as the available technological advances.

The effects of dietary acid detergent fibre content on the performance of finishing lambs

2025-03-24T16:15:42+00:00

This study investigated the effects of incremental increases in acid detergent fibre (ADF) content on the nutrient digestibility and performance of South African Mutton Merino wether lambs fed low-fibre finishing diets. Four dietary treatments were formulated with similar nutritional compositions, but with ADF concentrations of 46.8, 59.3, 63.8, and 79.9 g/kg dry matter. The digestibility study was conducted over seven days, while the production study was conducted over 67 days, after which the lambs were slaughtered. Significant differences between treatment means were declared at a 5% probability level. A high ADF concentration (79.9 g/kg) increased the finishing diet’s neutral detergent fibre and ADF digestibility. None of the other nutrients or dry matter digestibility values were affected by the change in ADF concentration. However, a low ADF concentration (46.8 g/kg) resulted in a significantly lower (more efficient) lamb feed conversion ratio, and less metabolisable energy was used for live weight gain. Carcass characteristics were unaffected by the dietary treatments. In conclusion, lamb performance was positively affected by a low ADF content in low-fibre finishing diets with a similar neutral detergent fibre content. More research is required to evaluate the effects of different ADF concentrations in highfibre diets on nutrient digestibility and the performance of wether lambs.