HEAT STRESS ▶▶▶
Vitamin E level and zinc source matter
BY DR. CIBELE TORRES H
igh feed prices alone are a major challenge but when poultry producers are faced with addtional challenges, such as heat stress, that puts even more pressure on controlling feed efficiency,
animal performance and farm profitability. Gut health plays an important role in making birds more resilient, healthy and on target given all the challenges they face, including heat stress. And the sooner gut maturation is positively modulat- ed, the greater gains can be achieved. Early intervention is key because the chick’s gut develops fast during early life. In the first 3 days after hatch, the absorptive nutrient area of the intestines increases by 70% (increase in villi length). This is essential because the chick needs to adapt quickly from a diet based on lipids (yolk lipids) to a solid carb/protein-based diet. Gut development is complete by 10 days and the mature gut microbiome is established around 17 days.
Zinc and vitamin E Over the years the industry has gained much more insight into how to determine and measure ‘intestinal health’ and how to positively influence that through nutrition and certain feed additives, such as zinc and vitamin E. Zinc and vitamin E are both vital antioxidants that protect the gut through different modes of action. But not all zinc sources on the market are the same and provide the same performance. The type of zinc used in poultry diets can therefore influence the optimum up- take of both zinc and vitamin E. Although responses to dietary
Figure 1 – Body weight (kg) at day 36. 2,800
Zinc and vitamin E are vital antioxidants that protect the gut and support broiler growth and health during heat stress conditions. The biggest gains are achieved by supplying them during the early days post hatch, while new research shows that more is not always better.
zinc and vitamin E have been investigated at different envi- ronmental temperatures, to the best of our knowledge, the interaction between different zinc sources and vitamin E levels has not been investigated under heat stress conditions in broilers. A study by De Grande and others (2021), published in the Journal of Animal Physiology and Animal Nutrition, looked at different levels of vitamin E in combination with different zinc sources. The trial looked at two sources of zinc, 60 mg/kg Zn as ZnSO4
or 60 mg/kg Zn as zinc amino acid complexes*
(hereafter called ZnAA), combined with two levels of vitamin E (50 or 100 IU/kg). Performance was measured from day 0-36. From day 28-36 (finisher period), all birds were subjected to chronic cyclic high temperatures (32°C ± 2°C and relative humidity 55-65% for 6 hours daily).
More is not always better It might be expected that feeding 100 IU of vitamin E after hatch would be more beneficial than the lower dosage used in this trial (50 IU), considering that during embryonic growth the embryo is consuming all vitamins and trace minerals to support its growth. However, this trial showed that ZnAA in combination with a lower dosage of vitamin E level improved body weight gain during early growth, at 10 days of age, and this effect continued during heat stress, at 36 days of age (Figure 1). This positive result is most probably due to
2,750
2,700 2,650 50 IU VitE 100 IU VitE ZnSO4 50 IU VitE 100 IU VitE ZnAA
Efficient antioxi- dants should be part of summer diets.
▶ POULTRY WORLD | No. 6, 2022 23
PHOTO: ZINPRO
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