Rifat Ullah Khan

Effect of vitamin E in heat-stressed poultry

Heat stress is associated with compromised performance and productivity in poultry due to declines in feed intake, nutrient utilisation, growth rate, egg production and quality, feed efficiency and immunity. Additionally, heat stress is characterised by reduced antioxidant status in birds, resulting in increased oxidative stress. Heat stress is also linked with increased economic losses due to mortality of birds. Vitamin E is a major chain-breaking antioxidant in biological systems. An optimum response with supplementation of vitamin E in feed has been found to improve feed intake, body weight gain, feed efficiency, egg production and quality, nutrient digestibility, immune response and antioxidant status in poultry birds. This work compiles past and present information about the role of vitamin E in heat-stressed poultry.

Effect of ascorbic acid in heat-stressed poultry

Two reviews are available in published literature relating to the effects of ascorbic acid on poultry performance. The first review was written by Pardue and Thaxton in 1986 who reviewed the role of ascorbic acid in alleviating the negative effect of heat stress in poultry birds. The second review was presented by Whitehead and Keller in 2003, who detailed the general effects of ascorbic acid in poultry birds, not taking into consideration ‘heat stress’. The first review is deficient in the literature published after 1986, while the second review does not describe the effect of ascorbic acid in heat stressed birds. The present review describes the past and present knowledge of ascorbic acid in alleviating heat stress in poultry birds with new aspects. Heat stress is associated with compromised performance and productivity through a decline in feed intake, nutrient utilisation, growth rate, egg production and quality, feed efficiency and immunity. Heat stress is also characterised by a reduced antioxidant status in birds, resulting in increased oxidative stress. Moreover, male fertility is decreased when birds are exposed to heat stress. Supplementation of 250 mg of ascorbic acid per kg of feed has been found to be optimum to improve feed intake, body weight gain, feed efficiency, egg production and quality, nutrient digestibility, immune response and antioxidant status in poultry birds. This work compiles past and present information about the role of ascorbic acid in heat-stressed poultry.

Antioxidants and poultry semen quality

Avian spermatozoa are characterised by high proportions of polyunsaturated fatty acids (PUFAs) which is associated with increased susceptibility to reactive oxygen species (ROS) and lipid peroxidation. Recent advances in avian reproduction have focused on the potential of ROS as one of the prime mediators of infertility. Although ROS are involved in many physiological functions of spermatozoa, their excessive production may result in oxidative stress. The production of ROS is enhanced during unfavourable environmental and stressful conditions, and an effective scavenging system is essential to counter the production of ROS. Antioxidants are compounds that suppress the formation of ROS. Enzymatic and non-enzymatic antioxidants build a powerful antioxidant system in avian semen which is able to protect it against ROS and lipid peroxidation. The balance between ROS and antioxidants in avian semen is a fundamental determinant of membrane integrity, sperm viability and fertilising ability. A regulating role of ROS in sperm function in mammalian sperm along with their counteractive mechanisms have been extensively studied; but their role for avian species reproduction remains to be elucidated. Various antioxidants belonging both to enzymatic and non-enzymatic groups can counter oxidative stress. Hence the rationale of using antioxidants is advocated.

Garlic ( Allium sativum ) supplementation in poultry diets: effect on production and physiology

Poultry researchers and nutritionists are looking for viable alternative feed additives since conventional supplements have been criticised for their potential negative impact on the food chain. Among the currently available poultry feed additives, natural herbs and plants have been widely advocated due to their reported widespread beneficial effects. Garlic (Allium sativum) is one such potential feed supplement which has recently been reported as having a wide range of beneficial effects on the production performance and physiological biochemistry of broilers and laying hens. Notable beneficial effects have been seen on growth, feed efficiency, egg production and quality, as well as stimulation of immune system and lowering blood cholesterol levels in poultry birds. The results reported vary from author to author probably due to variations in the dose of the product fed, the duration of feeding and processing techniques employed.

THYMUS VULGARIS: ALTERNATIVE TO ANTIBIOTICS IN POULTRY FEED

Due to the potentially undesirable effects of antibiotics as growth promoters in poultry production, researchers are looking for viable alternative to limit or replace their use. One such class of comparable alternative is natural source of herbs and medicinal plants. In the last decade, these alternatives have been increasingly used in broiler, layer and Japanese quail diets. Reports have variously claimed that medicinal plants, used as either the whole plant, their leaves or flowers, can enhance poultry performance. From the available literature, it can be concluded that thyme (Thymus vulgaris) belongs to such class of medicinal plant and may be an effective alternative to antibiotics in poultry production. In this review, its effects on different parameters of production performance in poultry are briefly discussed.

Potential applications of ginger (Zingiber officinale) in poultry diets

In the last decade, there has been growing interest in the use of natural herbs and medicinal plants as feed additives in poultry diets to maximise their potential output. Ginger is one such potential rhizome with a wide range of medicinal effects. In broilers and layers, this plant has been used in different forms, doses and durations. In this review, documented effects of ginger in poultry feed on feed intake and feed conversion ratio, growth and weight gain, carcass yield, egg production and quality, antioxidants and blood biochemistry, with their possible mechanisms of action, are discussed.

Effect of organic acid blend and Bacillus subtilis alone or in combination on growth traits, blood biochemical and antioxidant status in broilers exposed to Salmonella typhimurium challenge during the starter phase

ABSTRACT The present study was designed to find the effect of an antibiotic, an organic acid and a probiotic on performance traits, blood biochemical parameters and antioxidant status during the starter phase exposed to Salmonella typhimurium challenge. A total of 300 day-old broiler chicks were randomly allocated to control (basal diet), T1: infected with Salmonella enteric subsp. Typhimurium; T2: infected + avilamycin; T3: infected + organic acid; T4: infected + Bacillus subtilis; T5: infected + organic acid + probiotic. The results showed that body weight, feed conversion ratio and production efficiency factor did not differ (P > .05) between the control and treated groups. Blood albumin and aspartate aminotransferase increased significantly (P < .05) in birds in T5 during the first week. Similarly, total protein and triglyceride concentration increased significantly (P < .05) in T4 and T5. The total antioxidant capacity in the second week decreased significantly in T4 compared to the control. Thiobarbituric acid reactive substances during the first and second weeks did not differ significantly (P > .05) between the control and treated groups. We concluded that the effect of organic acid blend and B. subtilis was similar to that of the antibiotic in broilers during the starter phase exposed to S. typhimurium challenge.

The applications of probiotics in poultry production

The use of antibiotics in poultry feed as a growth promoter has been restricted in many countries around the world. Consequently, there is a growing interest in finding viable alternatives for growth enhancement and disease prevention in the poultry sector. Probiotics are considered alternative feed additives to antibiotics and can be defined as microbial food supplements which beneficially affect the host by improving its intestinal microbial balance. In this review, the special characteristics of probiotics and their mechanisms of action have been described. Probiotics enhance the growth and production of poultry birds, protect the host against pathogens, enhance the immune system, improve bone strength and fight parasitism. In the following paragraphs the available literature on the uses of probiotics in poultry production is reviewed.

Immunomodulating effects of vitamin E in broilers

Modern commercial broilers appear to have compromised immunocompetence, higher mortality and lower resistance to stressors. To overcome these, dietary manipulation seems to be the easiest approach, and this has been supported by research investigations conducted over the last few decades. The goal of enhancing the immune system of broilers is laudable for both economic and welfare reasons. Vitamin E (VE) is now well accepted as natures most effective lipid-soluble, chain-breaking antioxidant. This antioxidant vitamin has been shown to improve both cell-mediated and humoral immunity in broiler chicks. However, the effect of this vitamin depends upon dose, age and genetics of the broiler chicks. Several mechanisms have been postulated for the beneficial effects of this vitamin. In this review, several aspects of the immunomodulatory effects of VE are reviewed.

Evaluating the suitability of field beans as a substitute for soybean meal in early‐lactating dairy cow: Production and metabolic responses

Twenty-four multiparous Holstein cows were utilized in a completely randomized design to examine the effect of feeding field beans (FB, Vicia faba L. var. minor) as substitute for soybean meal (SBM) on lactation performance and metabolic response during the early lactation period. Cows were individually divided into two equal groups and fed for 16 weeks on one each of the two experimental diets. The controls were fed pelleted concentrate contained 150 g/kg dry matter (DM) of SBM as the main protein source, whereas the experimental concentrate contained 345 g/kg DM of FB. Oat hay was offered ad libitum to cows and water was freely available. Blood samples were assayed for their content of: urea, glucose, triglycerides, cholesterol, total protein, albumin, calcium and phosphorus, aspartate aminotransferase (AST) and alanine aminotransferase (ALT), nonesterified fatty acids (NEFA) and β-hydroxybutyrate (BHBA). Inclusion of FB had no detectable effects on DM intake (DMI), body weight (BW), or body condition score (BCS). Neither milk yield nor quality were influenced by dietary treatment, except for milk urea nitrogen (MU) that was reduced in cows fed the FB diet (P < 0.05). Clotting properties of milk were not affected adversely by added dietary FB. Concentration of blood urea (BU) was lower in cows fed the FB diet than in those fed the control SBM diet (P < 0.05). These findings indicate that feeding FB in a lactation diet supported lactation performance similar to cows fed traditional SBM-based diet, and the results may elicit great interest for countries where soybean utilization is adversely influenced by high supply costs.