Age-related changes in testicular histological structure, testosterone level, libido and semen traits in male Coturnix quail.

To investigate the effect of age in male quail on testicular weight and histology, sexual libido and semen characteristics, a study was performed on 100 quails at 10, 16, 22, 28 and 34 weeks of age. The body and testicular weights were significantly (p < .05) higher at 16 and 22 than at 28 weeks of age. The circumference and diameter of the seminiferous tubules were significantly (p < .05) higher at 28 and 34 than at 10 and 16 weeks of age. Histological evaluation of testicular slices revealed advanced and effective seminiferous tubes as early as 10 weeks, while spermatogenic activity peaked at 16 weeks of age. The highest semen volume, sperm motility and sperm concentration were observed at weeks of age and then decreased gradually with age. At the same time, the testosterone level and libido were significantly (p < .05) higher at 22 than at 10 weeks of age. Furthermore, the age was positive (p < .05), correlated to seminiferous tubule circumference and diameter, and negative (p < .05), correlated to sperm concentration. In conclusion, the age of quail markedly affected the testicular histological structure, libido, testosterone level and semen characteristics.

Impact of bee venom supplement on productive performance, health status and economics of weaned male rabbits: Considering breed and dosage factors.

The objectives of the present study were to investigate the potential effects of purified bee venom (BV) on various aspects of growth, carcass, antioxidant, intestinal bacterial count and economic considerations in rabbits. A total of 240 male rabbits, comprising two distinct breeds (V-Line and New Zealand White [NZW]), 5 weeks old, with an average live body weight (BW) of 680 ± 20 g, were randomly divided into six groups, each containing 30 rabbits. Each group had five replicates, with six rabbits in each replicate. The allocation of animals to the groups followed a fully factorial design, incorporating two factors: breed (V-Line and NZW) and four levels of purified BV derived from Apis Mellifera. The control group (G1) received a basal diet without additives. The other three groups (G2, G3 and G4) received the basal diet with BV supplementation in their drinking water at 0.5, 1 and 2 mg/L respectively. The study results indicated that NZW rabbits significantly enhanced feed conversion ratio while maintaining consistent carcass attributes compared to the V-Line breed. Despite variations in growth parameters being less pronounced, the supplementation of BV at levels of 1-2 mg/L demonstrated significant improvements in various other parameters. Notably, the interaction between the BV supplement and the breed factor (p < 0.001) yielded notable distinctions in most production metrics, encompassing BW, weight gain, feed conversion, carcass attributes and blood parameters. Increasing levels of BV supplementation, particularly at 1 mg/L, led to substantial improvements in serum and tissue metabolites. Moreover, the levels of total bacterial count and Escherichia coli in the jejunum and colon were significantly diminished, while the population of Lactobacilli in the colon was augmented (p < 0.001) in rabbits from both breeds receiving BV supplementation (1-2 mg/L) compared to the control group. The results underscore the potential of the BV supplement to enhance final weights, bolster antioxidant status and mitigate the presence of pathogenic bacteria, thereby contributing to enhanced economic efficiency in rabbits. Further inquiries are warranted to comprehensively investigate BV supplementation's potential advantages and limitations across different breeds and dosage levels.

Impact of dietary Moringa oleifera leaf supplementation on gut morphometry, behaviour and physiological parameters in growing male rabbits.

Moringa oleifera (MO), a cultivated species of the Moringa, is known for its high concentration of essential nutrients that promote growth. To assess its impact on rabbits' gut morphometric, behavioural, and physiological parameters, a study was conducted using sixty growing male white New Zealand rabbits at 40 days old. The rabbits were divided into four groups and supplemented with dried MO leaves at varying levels (0%, 0.5%, 1% and 2% of body weight) for four weeks. The results revealed significant increases in organ weights, such as liver and intestinal length, and the height of intestinal villi and crypt depth in the large intestine. The muscular layer's and submucosa's thickness also increased in different parts of the intestine in rabbits fed with MO compared to the control group. No significant effect was observed on the caecum mucosa depth. Interestingly, no significant differences were found in body weight or weight gain between the Moringa supplementation groups and the control group. However, rabbits offered 0%, 0.5% and 1% MO spent more time feeding and resting than those given 2% MO. The grooming and sniffing percentage remained unaffected by Moringa supplementation. Regarding blood parameters, rabbits that received MO leaves in their diet showed improvements in red blood cell count, haemoglobin levels, packed cell volume, white blood cell count, neutrophil count, total protein, globulin, and A/G ratio. Moreover, there was a significant decrease in malondialdehyde levels and an increase in glutathione and high-density lipoprotein levels, indicating an antioxidative effect. Overall, the study concluded that MO leaves supplementation in the rabbit diet positively influenced the rabbits' health by modulating the immune system, improving histological aspects of the intestine, liver, and spleen, and enhancing physiological parameters through its antioxidative properties.

Does the use of lactic acid as an antibiotic substitute in broiler diets affect growth, carcass traits, blood indices and intestinal microbiota?

The objective of the current study was to determine the impact of lactic acid (LAC) as an antibiotic alternative in broiler diets on growth performance, carcass traits, blood indices and intestinal microbial load. A total of 300 broiler chicks one day old (Ross 208) were allotted to five experimental groups in a complete randomized design experiment. Each group was subdivided into six replicates, each of ten unsexed chicks. The treatments were as follows: NC: negative control (basal diet); PC: positive control (basal diet + 0.5 g Colistin® antibiotic/kg diet); LAC2, LAC4, and LAC6: basal diet + 2, 4, and 6 cm3 lactic acid/kg diet, respectively. Results showed no significant effects of dietary treatments (antibiotic or lactic acid) on growth performance traits (body weight, BW; daily body weight gain, DBWG; feed intake, FI and feed conversion ratio, FCR) and carcass characteristics except for Thigh %. All blood biochemical traits were affected (p > 0.01) by dietary treatments. The highest values of blood total protein and albumin were found in birds of LAC2 group. Adding graded doses of LAC to broiler diets inhibited the activity of liver enzymes and reduced the concentration of blood urea. The positive effect of LAC supplementation excelled that of antibiotics regarding the antioxidant status parameters. The lowest pathogenic bacteria (E. coli and Salmonella) were recorded by LAC4 and LAC6 groups. It could be concluded that dietary supplementation of lactic acid did not significantly affect most growth performance traits. But its use could have beneficial impacts on blood parameters, oxidative status and intestinal microbial counts. Based on our results, the highest level (6 cm3 LAC/kg diet) is the recommended level for the best results.

Effect of dietary modulation of fiber and fat level on liver and kidney functions, lipid profile, antioxidant and immune parameters in growing Egyptian geese.

Determining the optimal requirements from dietary fiber and fat for Egyptian geese is a matter of great concern regarding health, production and growth. Therefore, the current study estimated the effects of different dietary fiber and fat levels on functions of liver and kidney, lipid profile, immunity and antioxidant measurements of the growing Egyptian geese. 150 Egyptian goslings (4 weeks old), with almost the same body weights were randomly allocated into 6 groups (25 goslings/group). All groups were subdivided into five replicates, each replicate contains five geese. Liver and kidney functions, immunity and antioxidant parameters were not significantly affected the different studied levels of fiber and fat or by their interaction. Various levels of fiber significantly affected total cholesterol, triglycerides, LDL-cholesterol and VLDL-cholesterol in a concentration-dependent manner and the lowest the lipid profile values were obtained at 12%. In conclusion, the present findings show that use of dietary fiber up to 12% and 5% dietary fat showed no detrimental effects on the immune status and general health of geese and resulted in the preferable lipid profile. This experiment provides a base for further study about the optimal requirements from dietary fiber and fat for the growing Egyptian geese.

Growth, sex reversal pattern, and reproductive characteristics of Barramundi (Lates calcarifer) broodstock candidates reared in floating cages.

Sex reversal of male to female is a characteristic of barramundi (Lates calcarifer), which is affected by several factors, thereby changing the broodstock population. A study was conducted in floating cages in Langkawi, Malaysia, to determine the weight point at the onset of the sex reversal phenomena. A total of 75 female and 55 male adult individuals (3-4 weeks of age) were sampled from the fish cultured in cages to ascertain their sex at different weights. The water temperature and salinity values were 29.82 °C and 33.12 ppt, respectively. The specimens were classified into twelve bodyweight classes (2.00-8.00 ± 0.5 kg intervals). Female specimen body weight distribution was highest in the 6.01-6.50 kg class (22.6%), followed by the 5.51-6.00 kg and 4.51-5.00 class (13.3%), while male specimen body weight distribution was highest in the 4.51-5.00 kg class (32.1%), followed by the 4.01-4.50 kg class (30.3%). Length-to-weight relationships for females and males of Asian Seabass indicated positive allometric growth. The correlation between body weight and GSI, using Pearson's correlation, for both sexes, for the male and female barramundi, there was a weak correlation between body weight and GSI, which was 37 and 30%, respectively. Based on the present study's findings, it can be concluded that sex reversal from male to female in Barramundi largely occurred at 4.57 kg body weight and 66.8 cm total length.

Sexual behaviour response, testicular development and semen quality of New Zealand white rabbit bucks as influenced by dietary chitosan.

The present study was conducted to determine the effects of dietary chitosan supplementation on sexual behaviour responses, testicular development, and semen quality traits of New Zealand White (NZW) rabbit bucks. Twenty-four 5-week-old rabbit bucks were used in this experiment. Animals were grouped into four equal experimental groups: the control group was fed only on a basal diet, whereas the other groups were fed the basal diet supplemented with three levels of chitosan at 0.2, 0.4, or 0.6 g/kg, respectively. Also, bucks that received chitosan at 0.2 and 0.4 g/kg had a significantly earlier time of sexual libido (p ≤ .05) and had significantly higher ejaculate volume and sperm concentration than other groups (p ≤ .001). Furthermore, basic and sexual behaviours were significantly improved in bucks fed chitosan at 0.2 and 0.4 g/kg compared with other groups. Therefore, it could be concluded that using chitosan at 0.2 and 0.4 g/kg enhanced sexual behaviour, improved semen quality, and reproductive efficiency in the NZW rabbit bucks.

Quercetin: Putative effects on the function of cryopreserved sperms in domestic animals.

Quercetin is one of the most used antioxidant flavonoids and largely exists in many fruits and vegetables because of its capability to scavenge the free reactive oxygen species (ROSs) by repressing lipid peroxy radical fusion, metal ion chelating through enzyme inhibition, and adopting the repair mechanisms. It also exhibits various biological actions, including antioxidative, anti-inflammatory and antimicrobial activities. Furthermore, it contributes well to sustaining the endogenous cellular antioxidant defence system. The process of cryopreservation is associated with increased oxidative stress, and some steps are potential sources of ROSs, including the method of semen collection, handling, cryopreservation culture media, and thawing, which result in impaired sperm function. Several antioxidants have been proposed to counteract the harmful impact of ROS during semen cryopreservation. The antioxidant capability of quercetin has been verified in different animal species for providing valuable defence to sperm during the cryopreservation process. The beneficial properties of quercetin on various parameters of fresh and post-thaw sperm in different species are clarified in this review. More in-depth investigations are required to clarify quercetin's mechanism of action in different animal species.

Impacts of polyphenols on laying hens' productivity and egg quality: A review.

There has been a rapid increase in the world's output of main poultry products (meat and eggs). This reflects customer desire for these high-quality and safe products and the comparatively low price. Recently, natural feed additives, plants and products have been increasingly popular in the poultry and livestock industries to maintain and improve their health and production. Polyphenols are a type of micronutrient that is plentiful in our diet. They are phytochemicals that have health benefits, notably cardiovascular, cognitive function, antioxidant, anti-mutagenic, anti-inflammatory, antistress, anti-tumour, anti-pathogen, detoxification, growth-promoting and immunomodulating activities. On the other hand, excessive polyphenol levels have an unclear and sometimes negative impact on gastrointestinal tract health, nutrient digestion, digestive enzyme activity, vitamin, mineral absorption, laying hens performance and egg quality. As a result, this review illuminated polyphenols' various sources, classifications, biological activities, potential usage restrictions and effects on poultry, layer productivity and egg external and internal quality.

Effect of different levels of pomegranate peel powder and probiotic supplementation on growth, carcass traits, blood serum metabolites, antioxidant status and meat quality of broilers.

The present study aimed to investigate the effect of dietary pomegranate peel powder (PPP) and probiotic bacteria (PB) on the growth rate, carcass traits, blood serum metabolites, and meat quality of Ross broiler chickens during 1-5 weeks of age. A total of 480 unsexed Ross broiler chicks 7-days old with the beginning bodyweight of 110.58 ± 0.17 g were employed in a complete randomized purpose trail with eight groups; 60 chicks in six replicates (8 × 6 × 10). The dietary treatments were as follows: NC: negative group (without additives) group one; PC: positive control (main diet + 0.5 g Colostin antibiotic/kg feed); PPP 3-5: basal diet + 2, 3, 4 g pomegranate peel powder/kg diet and PPP 6-8: basal diet + 2, 3, 4 g pomegranate peel powder + 1 cm3 probiotic (Bacillus toyonensis (BT)/kg diet, respectively. The results showed that live body weight (LBW) at five weeks and body weight gain (BWG) during 1-5 weeks of age were affected by adding PPP in the ration and the good grads of PPP were 2 and 4 g PPP without PB/kg diet compared to NC and PC, respectively. Otherwise, daily feed conception (DFC) and feed conversion ratio (FCR) were not affected by adding the different grads of PPP with or without PB, except the first period of DFC (1-3 weeks of old) were affected. Results showed a significant effect on all carcass characteristics studied, except gizzard and abdominal fat ratio were not influenced by the treatment used. Likewise, the addition of PPP to broiler chicken diets has a good effect on almost the blood serum metabolites, immunological parameters and quality of meat studied. In the end, the outcome of this study concluded that the addition of PPP to broiler diets has a good effect on the growth rate, blood serum metabolites, immunological parameters and the quality of meat as well as the health aspects.

Consequences of varying dietary crude protein and metabolizable energy levels on growth performance, carcass characteristics and biochemical parameters of growing geese.

This research aimed to investigate the effect of varying dietary crude protein (CP) and metabolizable energy (ME) quantity on growth, carcass characteristics, biochemical blood parameters and molecular aspects of growing geese. Overall, a total of 180 Egyptian goslings were used in a 2 × 3 factorial design. Two levels of CP (18% and 16%) and three levels of ME (3000, 2900 and 2800 kcal/kg diet) were employed. Growth traits showed no significant differences as a result of different CP or ME levels. Birds fed the higher CP level consumed more feed than the lower. Carcass, dressing, heart, spleen, abdominal fat and thigh percentages within the group fed 18% CP were higher than the other group. Compared with the other ME-based diet, geese fed a low-ME based diet had the highest heart percentage. Feeding growing geese on a 2900 Kcal/kg ME-based diet increased the serum content of total protein and globulin. Geese fed the high-ME diet showed the highest levels of ALP and C4 as compared with other ME levels. Regarding Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), different protein and energy levels did not affect the molecular weight of blood proteins of Egyptian geese during the growing phase. It could be concluded the levels of 16% CP and 2800 kcal/kg ME are enough to maintain the growth performance and the other physiological indices as well as molecular aspects.

Growth, immunity, relative gene expression, carcass traits and economic efficiency of two rabbit breeds fed prebiotic supplemented diets.

The current study designed to evaluate the effect of oligosaccharide supplemented diets on growth performance, histomorphometric changes, economic efficiency and genetic expression of some growth and immunity-relative genes. One hundred and twenty weaned male rabbits, six weeks of age of two breeds (NZW and APPRI) were randomly allocated into six equal groups; the first supplemented with 0.3% Mannan-oligosaccharide (MOS), the second supplemented with 0.05% Isomalto-oligosaccharide (IMO) and the third considered a control group. Each group contained ten equal replicates. The highest Final body weight and feed consumption were recorded in MOS and IMO groups compared with control. Fortified feed diet with IMO significantly increased duodenal villi area and length than MOS and control groups. At the same time, Spleen white bulb area and length were significantly higher in MOS and IMO than control. Supplementation of MOS and IMO significantly improved carcass traits, economic efficiency and induced certain modifications in some major key genes involved in the regulation of nutrients metabolism, immunity and growth in different tissues. In conclusion, dietary supplementation of MOS and IMO had a desirable positive impact on productive and economic efficiency in the rabbit.

Prebiotics can restrict Salmonella populations in poultry: a review.

Antibiotics were over the years, the common supplement used for poultry production. There is a global trend to lessen antibiotics' use due to the contamination of consumed meat with antibiotic residues. Also, there is a concern that human treatments might be jeopardized due to the emergence of antibiotic-resistant bacteria. Prebiotics are attractive supplements, particularly in poultry production, because of the diversity of their effects, including pH amendments, production of short-chain fatty acids (SCFA) and the inhibition of pathogens' growth. The commonly used prebiotics are carbohydrate sources that cannot be easily broken down by chickens. However, they can efficiently be utilized by the intestinal tract's microflora. Oligosaccharides, polysaccharides and lactose are non-digestible carbohydrate sources that are typically used in poultry diets as prebiotics. This review covers current applications and prospects for using prebiotics to improve poultry performance and reduce pathogens, particularly Salmonella, in gastrointestinal tract.

Effect of environmental factors on growth performance of Nile tilapia (Oreochromis niloticus).

Aquaculture is the practice of developing aquatic animals and plants under artificial environmental conditions, either in a controlled or semi-controlled environment. Due to high animal protein demand, it is one of the world's growing food production industries. It plays a vital role in contributing to food security and lowering the unemployment rate of the world's growing population. This review article aims to scope sight on the environmental factors that affect the growth and economic production process of Nile tilapia. Many of these factors are listed and analyzed in this review, such as stocking densities; various feed frequencies and feeding rates; water quality; water temperature; dissolved oxygen concentration; water pH degree; ammonia (NH3), nitrite (NO2), and nitrate (NO3) concentration; feeding regimes; feed cost; and tank culturing system of Nile tilapia. These factors can significantly alter body weight, composition, survival, behavior, feed intake, feed conversion ratio, feeding efficiency, and the health and reproduction of Oreochromis niloticus. Furthermore, feeding, growth, disease risks, and survival rates are all affected by water quality parameters. In general, higher growth performance of O. niloticus in aquaculture can be obtained by keeping the optimum quantity of feed with proper feeding rate and frequency, maintaining a good proportion of stocking density, and regularly evaluating water quality. This review article highlights-in details-the impact of various environmental factors on growth performance criteria of Nile tilapia (Oreochromis niloticus).

Impacts of sex steroids and aromatase inhibitor on performances, carcass characteristics and gonadal histology of broiler chickens slaughtered at different ages.

This experiment was established to evaluate the influence of synthetic steroid hormone and aromatase inhibitor on performance, carcass characteristics, hormonal profile and gonadal structure of broiler chickens slaughtered at two different ages. A total of 360 Cobb Avian48 chicks were sexed and distributed randomly into three groups: Tam10 group; birds received Tamoxifen10mg (Tamfen 10 mg@ ) orally at a level of 10 mg/kg body weight daily from the 3rd till the 9th day of age; BOL group: birds injected intramuscularly with Boldenone undecylenate (BOLD-GAN@ 0.1 mg/kg) at the 5th and the 9th day of age; and Control group. BOL injection or Tam supplementation improved performance traits compared with the control group. Although Tam positive effect appeared early before the 5th week of age, the BOL effect was delayed to the 6th week. BOL injection improved carcass characteristics of both sexes at both 5 and 6 weeks slaughtering ages. Regardless of treatment effect, the mortality% was higher in the late weeks of age than in the early weeks. Moreover, BOL treatment increased comb% compared with control and Tam treatments. Generally, males had significantly higher testosterone levels and lower oestrogen levels than females. Males treated with Boldenone had the highest testosterone level, although testosterone levels did not differ considerably among females of the various groups. BOL treatment females had the lowest oestrogen level. Both Tam10 and Boldenone had adverse effects on testicular and ovarian histology, affecting the typical structures. Finally, we concluded that the anabolic effect of Tam10 may be achieved in griller broilers production without changing the sex hormones assay. Although Boldenone achieved an anabolic effect without changing blood sex hormone levels, this effect is induced early with females and delayed with males, which prolongs the marketing period. The goal is to shorten this period. Therefore, this material can only be used with the possibility of separating females from males to be used with females only.

Responses of sperm mitochondria functionality in animals to thermal stress: The mitigating effects of dietary natural antioxidants.

The reproductive consequences of global warming representing heat stress (HS) have been widely received more attention in the last decades. HS induced significant influence on the male reproductive cell, especially sperm functionally. Reduction in the sperm function induced by HS leads to failure of fertility potential. The main effects of HS on sperm are reducing sperm motility, increased abnormalities and changes in the fluidity of the membrane as well as cell morphology. Moreover, the destruction of mitochondrial function could be the result of adverse influences of HS. The protein contents and enzymes of mitochondria were lowered after the exposure of sperm to HS. Some natural antioxidants were used for improving sperm mitochondrial function under HS conditions. In this review, it was highlighted the potential influences of HS on sperm function through reduction in ATP Synthesis yield, mitochondrial activity, mitochondrial protein contents and mitochondrial enzymes, which involves the interference of mitochondrial remodelling in sperm of animals.

Influence of dietary L-carnitine and lysine-methionine levels on reproductive performance and blood metabolic constituents of breeder ducks.

The present study aimed to evaluate the influence of dietary supplementation of different levels of L-carnitine and/or lysine-methionine (Lys-Met) on reproductive performance of breeder ducks. Three L-carnitine (0, 75 and 150 mg/kg) and three lysine-methionine (100%, 110% and 120% above the NRC (Nutrient requirements of poultry, 1994, National Academy Press) recommendations) levels were fed to 180 breeder ducks (144 females and 36 males) in a completely randomized design for 49 days. Laying performance and reproductive traits were evaluated; additionally, uric acid, total protein total, triglycerides, total cholesterol, low-density lipoprotein, high-density lipoprotein, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were assessed. The Lys-Met above 100% NRC (Nutrient requirements of poultry, 1994, National Academy Press) recommendations with or without L-carnitine improved feed utilization (p < .05). Furthermore, Lys-Met above 100% recommendations without L-carnitine improved egg fertility and hatchability. Fertility and hatchability improved in breeders fed on L-carnitine with 120% Lys-Met (p < .05). Serum glucose increased and total cholesterol reduced on 100% Ly-Met without L-carnitine or 110% Ly-Met with 150 mg L-carnitine (p < .05). Glucose was reduced, while total cholesterol increased on 75 mg L-carnitine and 100% Lys-Met (p < .05). Increasing Lys-Met without L-carnitine reduced serum protein (p < .05). Albumin and ALT increased on 75 mg L-carnitine-100% Lys-Met and reduced on 150 mg L-carnitine-120% Lys-Met (p < .05). There were no interaction effects on globulin, uric acid and AST (p > .05). Thus, based on findings, breeder ducks responded to dietary Lys-Met more efficiently than L-carnitine; however, more research is needed to evaluate also economic aspects related to L-carnitine dietary supplementation.

Betaine and related compounds: Chemistry, metabolism and role in mitigating heat stress in poultry.

Betaine can operate as an osmolyte and a methyl donor. Betaine is an osmolyte and a methyl donor. Betaine is likewise a zwitterion with osmotic capabilities that can help an animal cope with osmotic stress. Previous investigations have suggested that betaine has various impacts, albeit these studies do not consistently provide the same results. Dietary betaine has received a lot of attention owing to its osmoprotectant, methionine-sparing and antioxidant properties. Betaine is extensively assessed concerning performance and body composition. The tolerance to high temperatures, flock livability, and breast meat output is among the factors frequently mentioned in the literature as being altered by betaine. Betaine, a multi-nutritional agent, may help poultry resist heat stress and poor management. A common subject of betaine research is the idea of betaine saving some methionine. Although research on betaine may not always come to the same results, some discoveries repeat themselves. Because of their effectiveness in increasing growth performance, feed utilization, meat quality, and alleviating heat stress in chicken farms, betaine and methionine are extensively used as feed supplements in poultry diets. This review highlights the influences of betaine on poultry performance, meat quality, carcass characteristics, antioxidant activity, in addition to its role in mitigating heat stress.

Heat stress in poultry with particular reference to the role of probiotics in its amelioration: An updated review.

Global climate change is accelerating at an unprecedented rate, and the consequences of global warming are expected to worsen. Many heat waves have recently hit various parts of the world, causing major losses in livestock, particularly in the poultry sector, resulting in massive mortalities and catastrophic economic losses. Therefore, the current review sheds light on the effects of heat stress on the poultry industry, and discusses the factors relevant to these harmful effects on behavior, bone development, blood chemistry and physiological changes, pathogenesis, and immune responses. Potential methods to ameliorate the heat stress response in birds, with particular reference to the role of probiotics in controlling such problems, is further discussed.

Beneficial effects of rumen-protected methionine on nitrogen-use efficiency, histological parameters, productivity and reproductive performance of ruminants.

Providing essential amounts of balanced nutrients is one of the most vital aspects of livestock production. Among nutrients, protein has an essential role in many physiological functions of animals. Amino acids in needs for both high and medium yielding ruminant animals are not fully covered by microbial degraded feed sources in the rumen of animals, and they must be met by protecting the proteins from being broken down in the rumen; hence, the dietary supplementation of rumen-protected proteins (RPP), including mainly rumen-protected methionine (RPM), became imperative. Many researchers are interested in studying the role of (RPM) in ruminant animals concerning its effect on milk yield, growth performance, digestibility, dry matter intake and nitrogen utilization efficiency. Unfortunately, results obtained from several investigations regarding RPM indicated great fluctuation between its useful and useless effects in ruminant nutrition particularly during early and late lactation period; therefore, this review article may be helpful for ruminant farm owners when they decide to supplement RPM in animal's diet. Conclusively, supplementation of RPM often has a balanced positive influence, without any reported negative impact on milk yield, growth performance and blood parameters especially in early lactating ruminant animals and when used with the low crude protein diet.