Pomegranate peel relieves heat stress in broilers


In a recently published study, researchers found urea-treated pomegranate peel is effective in alleviating the adverse effects of heat stress in broiler chickens.


BY MATTHEW WEDZERAI T


he pomegranate peel contributes to about 26–30 % of the total weight of the pomegranate fruit. There- fore, the processing of valuable products from the pomegranate produce large amounts of the peel.


Besides the nutritional value, harnessing the peel into an en- hanced animal feed product would be an environmentally friendly move. The pomegranate peel is a rich source of polyphenols such as the flavonoids and hydrolysable tannins.


The study In the study, the researchers used a total of 200 day-old broiler chicks from a commercial hatchery to investigate the effects of the urea-treated pomegranate peel on growth performance, carcass and meat quality, intestinal morphology, and immunity in heat-stressed broilers. All broiler chicks were reared under thermoneutral temperatures until day 24, and then subjected to cyclic heat stress for 6 hours per day from day 25 to day 42. The fresh pomegranate peel was mixed with 10 g solid urea/kg of the peel dry matter and ensiled in 3 litre plastic buckets for two months before drying at 50 °C for 3 days. The study consisted of four dietary treatments as follows: • Control diet (0 UTPP g/kg feed); (UTPP = urea-treated pomegranate peel)


• 15 g UTPP/kg feed • 30 g UTPP/kg feed • 50 g UTPP/kg feed


Table 1 – Results of feeding treated pomegrante peel to broilers under heat stress.


Item 0


Villus height, μm Villus width, μm Crypt depth, μm


Villus height/Crypt depth 48


1401.3 200.60 136.67 10.26


Urea-treated pomegranate peel (g/kg) 15


30


1507.0 178.33 171.37 8.80


▶ HEAT STRESS | MAY 2021


1825.3 166.33 161.41 11.32


50


1800.7 159.00 161.40 11.16


Benefits of urea treatment Comparing the effectiveness of various chemical agents (urea, polyethylene glycol, and calcium hydroxide) in previ- ous studies, the researchers found urea to be the most suita- ble additive for ensiling the peel as it reduced the total polyphenolic compounds and total tannin contents while preserving the content of important antioxidant tannins (pu- nicalagin and ellagic acid). Following the processing of the peel with urea, the researchers found increases in the content of gross energy and crude protein, and dry matter digestibility.


Growth performance The urea-treated peel showed a significant increase in body weight gain, and an improved feed conversion, both, before and during the heat stress periods (day 25 – 42). No signifi- cant differences in feed intake were observed during the heat stress period, although values were slightly lower in the peel diets. “The beneficial effect of the peel on performance can be attributed to the peel’s anti-oxidative and immune-stimu- lating properties and ability to improve intestinal morpholo- gy”, the researchers remarked. The treatment with urea also increased the gross energy and protein content of the diet.


Carcass and meat quality Exposing broilers to heat stress reduces protein synthesis and promotes protein degradation in the breast muscle. In the study, an increase in carcass and breast yield was observed with increasing levels of the urea-treated pomegranate peel. They attributed the increase to the positive effects of the peel’s bioactive compounds on the antioxidant status of breast muscle. They also stated that the increase in breast muscle proportion might be a result of the improvement in growth performance. In addition, heat exposure increases the lipoprotein lipase activity while decreasing that of hormone-sensitive lipase, resulting in enhanced fat deposition in the abdominal cavity of broiler chickens. In the current study, the peel reduced the abdominal fat proportion; the researchers’ explanation was that this is possibly via inhibiting the activity of pancreatic lipase and activating the AMP-activated protein kinase


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