Heat stress in animal production is a worldwide problem which occurs constantly in tropical countries and often in temperate countries during summer. This phenomenon has a negative impact on animal production, as it decreases the animals’ comfort and penalises their performance. Heat stress occurs when an animal is no longer capable of naturally eliminating excess body heat. Heat build-up is caused by external temperatures and a high level of relative humidity (RH), which overtakes the physiological capacity of thermoregulation, or evapotranspiration, in animals.

Sensory additives for wellbeing

Based on its three areas of expertise– plant extracts, galenic and cerebral approaches – Phodé developed a neurosensorial solution, mainly composed of a specific extract from the Rutaceae family, which modulates the stress message signals in the central nervous system. As a result, animals perceiving environmental stress, such as heat, can adapt more quickly to the situation. In other words, fewer changes will be observed in their behaviour, such as feed intake or social interaction, during stressful periods.

Results in broilers

In tropical countries, broilers naturally reduce their feed intake, especially under hot afternoon conditions, to reduce thermogenesis. As diet-induced thermogenesis occurs four hours after feed intake, some producers stop feeding birds in the morning to avoid late afternoon thermogenesis. In such feeding patterns birds are expected to balance out this lack of consumption early the next morning. However, it is often found that as global feed consumption decreases, so does growth rate. The economic impact of heat stress on broilers is estimated at US$0,15 to US$0,25/bird (around R2,35 to R4). On an experimental farm in the Philippines (34 to 36°C, Rh >80%), 20 000 broilers were divided into two groups (five replicate groups of 2 000 broilers). Hot conditions were particularly intense between 12:00 and 16:00 (Figure 1).

The group that received a plant-based extract, mainly composed of a specific extract of the Rutaceae family, exhibited higher, stable feed intake, especially during hot conditions. The feed conversion ratio for the supplemented group was positively impacted (-4%). A higher water intake was also noted during the hot period, highlighting the birds’ behavioural adaptation.

Figure 1: Daily feeding pattern of broilers from 30 to 35 days of age (%).

Results in sows

The ideal temperature for lactating sows is between 18 to 20°C, while it is above 30°C for newborn piglets. Sows face heat stress during the lactation period, which will affect their feed intake capacity. It has been proven that in temperatures above 25°C, sows’ feed intake is negatively impacted (-385g/sow/day compared to 18°C) and this impact continues to increase after 27°C (-923g/sow/day). The economic impact of heat stress on lactating sows is estimated at US$120 to US$330/sow/year (around R1 870 to R5 200).

In several trials conducted in different countries, the feed intake of lactating sows that received the plant-based extract was higher (an increase of 170 to 820g/sow/day). Benefits depended on the severity of the stress. Higher sow feed intake also generated better litter weight gain from birth to weaning (+3,5kg/ weaned litter and +4,3kg/weaned litter).

Results in dairy cows

In dairy cows, the intensity of heat stress can be estimated by the temperature-humidity index (THI), with the comfort THI threshold set at 68 (T 24,5°C, RH 15% or T 22°C, RH 45%). The economic impact of heat stress on dairy cows is estimated at US$32 to US$66/ dairy cow/month of milking (around R500 to R1 100).

In a trial conducted in Portugal (THI = 80), the relationship between THI and milk production was investigated using two groups of dairy cows (53 multiparous/57 DIM, and 76 primiparous/150 DIM). The groups whose diets were supplemented with the plant-based extract showed a higher milk yield of +2,6% for multiparous cows (control = 40,4ℓ/ cow/day vs solution = 41,5ℓ/cow/day) and +2,3% for primiparous cows (control = 30,3ℓ/ cow/day vs solution = 31ℓ/cow/day).

Under moderate heat stress, the plant-based extract helps to maintain milk yield by preserving normal drinking and feeding behaviour. From a specific cerebral mode of action, Phodé’s neurosensory solution appeared to be an effective tool for heat stress management for all species. – Aurélie Auvray, Guillaume Desrousseaux and Jean-François Gabarrou, Phodé, France

For enquiries, contact Liezel Olivier of Olfactum Nutrition
on 082 572 0141 or liezel@olfactum.co.za.