HOUSING ▶▶▶
Novel approach to reduce cold stress in layers
BY MATTHEW WEDZERAI B
esides the frequent and intense heat waves caused by global climate change, extreme low temper- atures during the winter months have also been observed. In laying hens, a cold temperature is a
common environmental stressor that manifests through in- creased feed intake, along with compromised health and egg production; all leading to economic losses. Environmental and heat transfer data show that laying hens lose about four times more energy during cold weather to maintain their body temperature. The detrimental effects of cold stress on hens can be even more severe towards the end-of-lay when hens have lost a considerable amount of their plumage cover. Common methods used to prevent cold stress, such as re- ducing ventilation and increasing the ambient temperature (usually by using gas heaters), present challenges due to poor indoor air quality, posing a threat to bird and caretaker health. Poor air quality due to reduced ventilation and high temperatures in the barn facilitate the build up of ammonia and dust, leading to increased susceptibility to disease.
Perch system study The aim of this study was to examine if a warmed perch system, as a thermal device, could reduce cold stress-related adverse effects in laying hens. At 32 weeks of age, 72 laying hens were randomly housed in two-bird cages arranged in three banks and then assigned to 1 of 3 treatments: (1) warm perches (perches with circulating warm water at 30°C);( 2) regular perches; and (3) no perches (Table 1). The trial was for a 21-day period. In the warm perches trial, two temperature detectors were installed in the two loops to measure the supply and return water temperature. Similarly, a single point for the regular perch was also measured. Cold stress was set at 10°C and the ventilation system was fully operational throughout the entire experimental period. Feed and water were provided ad libitum.
Perching behaviour and thermoregulation The warm perch system was found to be better compared to either the regular perch or no perch system in terms of perch- ing behaviour and thermoregulation. The foot surface tem- perature of hens standing on warm perches was higher than the hens roosting on the regular perches. Rectal temperature
▶ POULTRY WORLD | No. 2, 2022 13
A new study shows that a warmed perch system, as a thermal device, improves hen health and welfare by reducing cold stress-associated adverse effects in laying hens. Providing warm perches for laying hens has beneficial effects in terms of maintaining body temperature and feed intake without compromising body weight, egg production and egg quality under cold conditions.
was also higher in both the warm perch and regular perch system than with the no perch system. A greater proportion of birds in the warm perch system exhibited perching behav- iour than the birds with the regular perch system. To evaluate how the differences created by the three perch- ing systems affected thermoregulation, the researchers measured plasma concentrations of two thyroid hormones (3, 3’, 5-triiodothyronine (T3) and thyroxine (T4)). Thyroid hor- mones are actively involved in the regulation of thermogene- sis and energy metabolism. Cold exposure has been shown to enhance the conversion of T4 to T3 to increase heat produc- tion in birds. In this study, T4 was higher in both the warm perch and no perch groups than in the regular perch group.
The aim of this study was to examine if a warmed perch system, as a thermal device, could reduce cold stress-asso- ciated adverse effects in laying hens.
PHOTO: KOOS GROENEWOLD
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