Litter quality is an important component of many production systems, especially in turkeys because they remain in contact with the litter throughout the growing period, according to Dr Muhammad Waseem Mirza of SAC. He was speaking at this year's Turkey Science and Production Conference in Macclesfield, UK.

A previous study by the same group showed that the concentration of dietary protein can influence the quality of the litter and the leg health of turkeys but it was unclear whether the effect was from the absolute protein level or the ratio between dietary protein and energy. So the SAC researchers conducted another trial using different nutrient densities but holding the protein:energy ratio constant. They looked at the performance of growing male turkeys to 20 weeks of age, as well as nutrient digestibility, water intake, litter condition and the incidence of hock burns and foot pad dermatitis.

The diets were based on wheat and soybean meal and formulated to contain 77, 85, 100, 110 or 120 per cent of the crude protein and metabolisble energy content recommended for the breed standard, BUT 8.

Overall bodyweight was higher than the breed standard at the end of the trial at 20 weeks of age, said Dr Mirza. Nutrient density had positive and linear effects on weight gain, feed efficiency and dry matter digestibility. The effect on nutrient density on nitrogen digestibility, however, were not statistically significant. As expected, increasing dietary nutrient density had a negative and linear effects on feed and water intake.

Increasing nutrient density had positive effects on litter quality, with both litter moisture and litter score decreasing linearly. However, litter ammonia increased as nutrient density increased, as did the prevalence of hock burns. There was no effect of treatment on foot pad dermatitis in this trial.

Hock burn was related to water to feed ratio, feed efficiency, water intake and ammonia in the litter, said Dr Mirza. Foot pad dermatitis was associated only with the water-to-feed ratio.

Also interesting was that hock burn score was not linked to wet litter but rather to litter ammonia, said Dr Mirza.

He suggested another possible link between nutrient density and hock burn score: birds fed the more nutrient-dense diets spent less time eating and more time resting on the litter.

Other researchers have reported that foot pad dermatatis is associated with wet litter but the latest SAC research suggests that the combination of high litter moisture and ammonia concentration may be needed to predispose turkeys to foot pad dermatitis.

Dr Mirza concluded: "The results suggest that an increase in nutrient concentration can reduce the moisture content of the litter and so improve overall litter quality.

"However, the incidence of hock burn increased with the most nutrient-dense diets, suggesting that factors other than litter moisture may contribute to the occurrence of leg problems in turkey production."

Diet nutrient density affects the score for hock burn but not foot pad dermatitis

Reference

Mirza, M.W., V. Pirgozliev and N. Sparks. 2011. Diets based on different energy and protein concentration: effect on nutrient digestibility, growth performance, litter quality and leg health in turkey production. Proceedings of Turkey Science and Production Conference, Macclesfield, UK. 30 March to 1 April 2011. 63-65.

August 2011