Overview of beneficial additives not commonly used in poultry

Bee glue

Bee glue contains a substantial amount of protein (25 – 40%) with amino acids such as alanine, arginine, asparagine, aspartic acid, glutamic acid, glycine, lysine, methionine, phenylalanine, serine, threonine, tyrosine, and others, all of which are needed for better growth performance.

Broilers

In one study, body weight increased by 2.03% in broiler chickens fed with 0.1% bee glue compared with un-supplemented controls. Bee glue also has antioxidants, antiviral, antibacterial, anti-inflammatory, and wound healing activities which are needed for body health and condition. Further, it was reported that bee glue (200 mg/kg) increased the aroma, taste, juiciness, and softness properties of the breast and thigh muscles of broilers, without influencing other meat quality score indicators, including pH, colour, or cooking losses.

Layers

For layers, egg mass and eggshell quality were increased after feeding 100 and 150 mg bee glue/kg diet. In addition, shell thickness and eggshell weight for heat-stressed layers fed bee glue were significantly increased. The positive effects of bee glue on eggshell quality could be linked to an increase in calcium digestibility and absorption due to its acid derivatives such as 4-hydroxy-benzoic acids. Bee glue has also been reported to exhibit antibacterial and antifungal activities in embryonated eggs, as it positively affects the microbiological quantity and quality of eggshells and the internal contents of the eggs. Thus, bee glue could be an alternative hatching egg disinfectant to chemical compounds currently used without adversely affecting hatchability.

Black cumin

Broilers

One study showed that the addition of black cumin seeds to broiler diets at 10 grams/kg resulted in improved feed intake, body weight, and feed conversion at 42 days of age. The enhanced feed intake is attributed to black cumin seeds’ improvement of diet palatability and the resulting enhanced appetite of the birds. The higher body weight and feed efficiency observed with the black cumin diet could be attributed to the fact that the seeds serve as growth promoters and may be promising performance improvements, particularly in terms of feed efficiency, weight gain, and immune system.

Broiler growth performance

In addition, black cumin seeds have other pharmacologically positive effects on the growth performance of broilers which may also be attributed to their content of volatile oil or essential oil. It has been shown that the essential oil has certain biological functions that could act not only as an antibacterial and antioxidant but also as a stimulant of digestive enzymes in the intestinal mucosa and pancreas that improve digestion of dietary nutrients and feed efficiency, subsequently increasing growth rates.

Layers

Feeding of high dosages of powdered black cumin seeds to laying hens has been shown to reduce the population of harmful E.coli, probably due to its high content of crude acetone extract. Further, the population of the beneficial bacteria Lactobacillus tends to increase with the feeding of black cumin. These results suggest that the use of black cumin seed could be an effective alternative to synthetic antibiotics for the promotion of poultry health and performance. Besides, it is environmentally safe and the costs for commercial feed formulation are low.

Garlic powder

Garlic (Allium sativum) contains about 17% protein, 0.8% fat, and 3% minerals, with varying amounts of vitamins (thiamine, riboflavin, and niacin) and enzymes (alliinase, peroxidase, and myrosinase). In addition, it contains about 0.2% volatile oils, which are released when the plant is processed into powder, which is used for various therapeutic purposes.

Weight gain & FCR

Feed intake was reduced with garlic supplementation, probably due to the associated flavour factor, and the need of chickens to get adapted to the supplement during the first few weeks of feeding. However, the weight gain and feed conversion ratio were both better for the garlic-fed chickens, suggesting greater feed efficiency and utilisation.

Carcass quality

In most of the studies, no differences in carcass yield and quality have been reported for either the control or the garlic-fed chickens. Thus, the dressing percentage, the relative weights of the thigh, drumstick, breast, and abdominal organs, and the moisture level of the carcasses were essentially the same for both groups. In many cases, however, the oxidative stability of refrigerated chicken meat was improved by adding garlic powder to the diet, suggesting a preservation action of the garlic over extended periods.

Layers

Hens fed on garlic at 1% of their diet produce 9% more eggs compared with those in the control group. They have also demonstrated an increase of 3.5, 0.6, 0.3, and 2.7 grams in egg weight, yolk weight, shell weight, and albumen weight respectively, regardless of the method of preparing the garlic supplement.

Dried fig

Dried figs could serve as a source of natural enzymes such as cellulase, xylanase, and glucanase. These enzymes can be useful in poorly digestible diets containing high levels of barley or other grains. The high viscosity of the gut contents with such diets reduces digestibility and utilisation.

Chick performance compared

A recent study was conducted to compare the performance of chicks that are fed diets supplemented either with artificial enzyme premixes or dried fig meal. Growth rate and feed efficiency were increased by 7% and 12%, respectively by feeding the dried figs. At the same time, water consumption and mortality were reduced by 3% and 1.8%, respectively. Economically, dried fig diets cost less than those containing commercial enzyme preparations.

Green tea leaves

Green tea leaves (Camellia sinensis) have been used in the field of therapeutic nutrition, mainly because of the presence of polyphenol derivatives such as carnitine and catechin, which play an important role in fatty acid oxidation and the production of ATP. These derivatives also play an important role in the prophylaxis and/or treatment of neuropathic diseases, striate opacity, pancreatitis, fibroid tumours, etc. The effects, however, have so far been observed with laboratory animals only and further work is needed to determine the potential role of tea leaves in the therapeutic nutrition of poultry.

References are available upon request.