Across the world, cattle, poultry, and swine producers are faced with the challenge of managing heat stress in their animals when they are exposed to high environmental temperatures and relative humidity levels. For example, pigs often display signs of heat stress when exposed to an ambient temperature of 31°C or more, which makes it a big challenge for production in many countries.

Heat stress activates strain responses in livestock such as reduced feed intake and increased blood flow to the skin as the animals attempt to dissipate the heat. These responses impair gut health and growth as well as increasing mortality, in turn impacting farm animal welfare and productivity. The potentially significant reduction in performance and profitability means that animal production industries are always on the lookout for innovative ways to alleviate the issue.

On-farm management solutions, including adequate ventilation, lower stocking densities; cooling options, and increasing water intake can all help, but implementing structural changes to barns, pens and poultry houses is often neither practical nor within budget. What are the more achievable alternatives to manage the issue?

HOW FEED STRATEGIES CAN HELP

One important area to consider is the impact nutritional strategies, including feed additives, can have to mitigate the negative effects of heat stress across livestock species.

One option is to use a natural betaine additive in animal feed for its osmotic ability and to aid the animal’s metabolism. For example, Vistabet is a natural betaine source extracted from sugar beet molasses. It is used as a feed additive across production animal species as an osmoregulatory and osmoprotectant to mitigate variations in salt concentration and temperature, helping animals keep a water and ion balance during heat stress and eventually improving performance in several stress situations, including heat stress and disease challenge. It is also used as a methyl donor to support the metabolism.

An osmoprotectant drives a process that reduces nutrient absorption (coccidiosis, feed and water restriction during transportation and heat stress) and increases the osmotic pressure in the intestinal lumen. Water then flows to the lumen, trying to equilibrate the concentration. Betaine prevents water flow to the lumen, maintaining enterocyte integrity and nutrient absorption during challenge.

Betaine also helps to maintain protein structure, enzyme activity and consequently cell survivability in hyperosmotic environments common in kidney, liver, lung and intestines. This all helps to improve slaughter characteristics, including carcass breast meat yield in poultry.

WHERE’S THE EVIDENCE?

Working with a leading research centre in India, we investigated how our Betaine product, Vistabet, improved broiler performance and spared synthetic choline and methionine in broilers raised in chronic heat stress.

The experiment compared the use of natural betaine, which commercial name is Vistabet 96,  in two different strategies – over the top (Positive Control) or in a diet partially reduced in choline and methionine (Negative Control).

A statistically significant 1,400 Cobb  (40-days-old) were housed in 72 pens measuring. The animals were assigned to one of nine treatments in a randomised block design. 8 pen replicates (4 pens of males and 4 of female) of 20 birds per pen.  Birds were fed a 3-phase feeding program (Starter: 0-14 d; Grower: 15-28d and Finisher: 29-42d), offered as mash, with feed and water offered ad libitum.

• Positive control diet was  supplemented with 0, 250, 500, 750 and 1000g/t of Vistabet 96

• Negative Control (reduced by 500g/t of Choline Chloride 60% and 500g/t of DL-Methionine) supplemented with 0, 500, 750 and 1000g/t of Vistabet 96

Throughout the trial, the birds were kept above optimum temperature highlighted by Cobb manual guide for 70% relative humidity. The light routine adopted was 24 hours of light on the first seven days, and then 23 hours throughout the rest of the trial. This helped to mitigate the reduced feed intake of birds exposed to heat stress.

Body weight (BW) and feed intake (FI) were determined at every dietary phase change, and average body weight gain (BWG), FI and feed conversion ratio (FCR), calculated. Mortality was recorded daily. At the end of the trial FCR was corrected to a standardized body weight of 2.17 kg (bwcFCR) with a factor of 28g weight difference corresponding to 1 FCR point. European Production Efficiency Factor (EPEF) was also calculated at the end of the trial.

Data was submitted to two-way analysis of variance (sex x treatment) and when differences were seen (P ≤0.05), means were then separated using Student’s T-test. Additionally, linear and quadratic contrasts were performed on PC and NC diets. Liveability was analysed by Chi-square

TRIAL RESULTS

Over the overall trial period, Vistabet improved performance (BW, BWG, FI, FCR, bwcFCR and EPEF) of birds regardless of the type of diet (P<0.05), with BW being improved linearly on both PC and NC fed birds, FI, bwcFCR and EPEF were improved linearly in both PC and NC fed birds, while it also presented a quadratic pattern on NC fed birds. For FCR, both linear and quadratic regressions were significant (P<0.05). Males presented better performance than females, although liveability tended to be greater for females (1% better liveability, P=0.06).

In the first 14 days interactions were seen for feed intake, but no clear distinction on the behaviour of Vistabet effect on feed intake was seen in any of diets or sex, with interaction noticed because birds fed 750g/t Vistabet on the PC diet showing a very distinct intake (males being inferior to females). Vistabet inclusion on PC fed birds presented a quadratic response on BW and FCR, with optimum dose rate being around 500-750g/t. No clear pattern of Vistabet inclusion was observed on NC fed birds, however, best performance was obtained on birds fed with 500g/t of Vistabet.

From day 15 to 28, interactions were seen for feed intake from 15-28d, and at this age range we start seeing that Vistabet inclusion does not show any effect on intake of males, regardless of the diet offered, while on females we see a quadratic response with intake being lowered at intermediate dose rates of Vistabet. Looking for the main effects, Vistabet effect becomes more evident on both diets. Linearity on Vistabet effect was observed on birds fed either the PC or NC for BW, BWG, FI and FCR (P<0.05). However, we start noticing a distinction on the behaviour of the different strategies on BW (P=0.08) and FI (P<0.05), with these presenting a quadratic behaviour on NC fed birds, while on PC fed birds Vistabet also presented a quadratic FI behaviour (P<0.05).

No interactions were seen from day 29 to 42. The different behaviour of Vistabet on PC and NC fed birds persists, and although we see linearity on both PC and NC fed birds on BW, FI and FCR (P<0.05), we also notice that Vistabet’s effect on NC fed birds presented a quadratic behaviour on BWG and FCR (P≤0.05 – although worth noticing that main effect of treatment was not observed on BWG).

CONCLUSIONS AND IMPLICATIONS

Vistabet natural betaine improved performance of broilers submitted to chronic heat-stress, with the optimum dose rate being between 500-750 g of Vistabet 96 per tonne of feed. To mitigate the extra cost of inclusion of Vistabet, a reduction in synthetic methionine and choline can be made, without compromising performance.

A difference on response of Vistabet inclusion was noticed between PC and NC fed birds. This difference was caused by the reduction of choline (500g/t) and methionine (500g/t) on negative control diets. From the results of this trial, we can conclude that Vistabet, besides of improving performance, can serve as a strategy to spare methyl donors (choline and methionine) in broilers diets.

Although this trial was for broilers, we have evidence of the effectiveness of betaine across the species and believe it to be a valuable asset for producers looking to reduce the impacts of heat stress using a nutritional strategy.