Veterinary Research Forum

Abstract This study aimed to examine the effects of varying levels of L-carnitine and omega-3 and omega-9 fatty acids on performance, blood parameters, and testicular histomorphometry in fattening male Moghani lambs. Thirty-five five-month-old male Moghani lambs (27 ± 600 kg) were individually housed and randomly assigned to five dietary treatments. Diets included a control and four diets containing 3% calcium salts of omega-3 or omega-9 fatty acids with 100 or 200 mg/kg DMI of L-carnitine. Lambs were fed for 75 days to evaluate growth performance, nutrient digestibility, blood metabolites, carcass traits, and testicular histomorphometry.The results indicated significant effects on daily weight gain during the second month, average weight gain in the second month, and feed conversion ratio in the third month (P<0.05). However, glucose, total cholesterol, LDL cholesterol, triglycerides, blood urea nitrogen, and HDL cholesterol levels on day 30, as well as triglyceride levels on day 60, were not significantly influenced by dietary treatments. Blood urea nitrogen and HDL cholesterol levels, along with total protein, were significantly affected on day 60, with dietary treatments having a marked influence (P<0.05). Liver enzyme activities, including aspartate aminotransferase (AST) and alanine aminotransferase (ALT), were significantly affected during the first 30 days of the study (P<0.05), while alkaline phosphatase (ALP) activity remained unaffected over the 30 and 60-day periods. Testicular histomorphometry showed significant effects of dietary treatments on spermatogenesis index, seminiferous tubule diameter, and Leydig cell count (P<0.05).

Abstract The present study was conducted to investigate the effect of L-carnitine (LC) supplementation in diets containing different levels of fish oil (FO) on performance, egg quality parameters and egg yolk fatty acids (FAs) profile in aged laying hens. In this study, 432 laying hens (Hy-line-W36, 65 weeks of age) were used allocated in a 3 × 3 factorial design with 6 replications and 8 birds per replication. The experimental treatments included diets containing 3 levels of FO (0, 1.5 and 3% of the diet) and 3 levels of LC (0, 300 and 600 mg/kg of the diet). The results showed that hens treated with 3% FO and 300 and 600 mg LC had the highest egg production rate, egg weight and egg mass, which was significantly higher than the treatments without FO and LC. With increasing usage level of FO to 3% of diet, egg yolk pH decreased significantly (p <0.05), however, yolk pH increased when diet supplemented with 600 mg LC. The percentage of polyunsaturated FAs (PUFA), the ratio of PUFA/saturated FAs (SFA) and the percentage of omega-3 FAs increased significantly with increasing FO usage level in the diet (p <0.05). Therefore, the use of LC in a diet containing FO not only increased egg production performance and egg internal quality (Haugh unit and yolk color) of aged laying hens, but also increased the production and deposition of omega-3 FAs in egg yolk.

Abstract To mitigate metabolic disorders and skeletal abnormalities associated with rapid growth in broilers, and to reduce reliance on antibiotics, strategies involving feed restriction and non-antibiotic dietary additives are increasingly explored. This study investigated the effects of various feeding methods and additives on weight gain, feed intake, feed conversion ratio, carcass characteristics, intestinal morphology and ileal digestibility in broiler chickens. The research involved 480 one-day-old Ross 308 male broiler chickens. A 2 × 5 factorial experiment, arranged in a completely randomized design, incorporating two feeding methods (without and white quantitative restriction) and four types of additives including thyme essential oil (300 g per ton), oregano essential oil (300 g per ton), equal weight ratio of thyme and oregano essential oil (300 g per ton) and probiotic (250 g per ton) along with control diets (without additives). Dietary supplementation with oregano essential oil significantly increased weight gain compared to the other additive groups. While the feeding method, additives and their interactions significantly influenced feed intake in chickens and the feed conversion ratio was primarily affected by the type of additive. Supplementation with any of the tested additives led to reduced total feed intake and improved final feed conversion ratio compared to the control group. Histological analysis revealed that chickens receiving oregano exhibited the highest villus height to crypt depth ratio. In conclusion, this research suggested that quantitative feed restriction, particularly when combined with specific dietary additives such as oregano essential oil could significantly improve broiler growth performance, feed efficiency and intestinal morphology, offering potential alternatives to conventional practices.

Abstract American foulbrood (AFB) and European foulbrood (EFB) diseases caused by Paenibacillus larvae and Meliscococcus plutonius are prevalent honeybee brood diseases that pose significant economic challenges to the apiculture industry globally. Antibiotic treatment has led to the emergence of antibiotic-resistant strains, encouraging the search for alternative and safe measures to effectively control these diseases. Honeybee gut microbiomes have proven effects on all spectra of honeybee health by enhancing resistance to several diseases via immune modulation and the production of different antimicrobial metabolites. The major part of the gut microbiota is identified as probiotic bacteria, which are live microorganisms that, when administered in adequate amounts, confer health benefits to the host. Probiotics have shown promising health benefits for honeybees. Honeybee gut probiotics provide protection via the production of different metabolites (postbiotics), such as hydrogen peroxide, vitamins, organic acids, free fatty acids, bacteriocins, neurotransmitters, secreted bio-surfactants, and reactive oxygen species. Vast numbers of these gut bacteria and their postbiotics have wide-spectrum antibacterial effects on AFB and EFB. This review highlights the significance of the honeybee gut microbial community, its probiotic potency, and the role of postbiotic metabolites as safe prophylactic measures for preventing AFB and EFB diseases in honeybees.

Abstract While severe shortage of feed has presented livestock industry with a major challenge, millions of tons of fruit by-products (FBPs) are discarded annually, as valuable sources of energy and numerous nutrients. However, some of FBPs contain high tannins that must be treated for use in animal feeding. This study was investigated the effect of tannin-degrading bacteria isolated from the rumen of some ruminants on the in vitro digestibility and gas production of FBPs silage. The FBPs, including pomegranate peel (PP), and the pulps of lemon (LP), grape (GP), and orange (OP) were ensilaged with tannin-degrading bacteria (enzyme activity: 10.46 - 8.60 U mL^-1) isolated from the rumen of male goat (Escherichia coli GHMGHE41), deer (Escherichia fergusonii GHMGHE44), ram (E. fergusonii GHMGHE30), and camel (Klebsiella aerogenes GHMGHE38). After anaerobic incubation (30 days; 39.00 ˚C), PP + camel strain silage showed the highest dry matter, and the lowest natural acid detergent fiber and pH. The camel strain increased crude protein content of LP silage to the highest level, and decreased acid detergent fiber of GP silage to the lowest level. The highest digestibility was observed for LP + goat strain silage (50.37%) compared to the uninoculated OP silage (42.73%). The maximum ammonia (N-NH₃) and minimum level of pH were recorded for the silages of LP + goat strain and PP + CR strain, respectively. Overall, the current results showed that tannin-degrading E. coli GHMGHE41 and K. aerogenes GHMGHE38 were able to improve the digestibility of LP and PP silages as ingredients in ruminants’ diets.

Abstract The aim of this study was to investigate the effects of using a Rovabio^® Plus multi-enzyme on production and reproductive performance, duodenum morphology and biochemical parameters in 45 - 60 weeks old broiler breeders. For this purpose, 260 broiler breeders of Ross 308 strain were used in a completely randomized design with four treatments and five replications (13 hens and one rooster in each replication). Experimental treatments included: 1) Positive control diet (diet with standard energy and phosphorus and without multi-enzyme), 2) Negative control diet (diet in terms of energy 5.00% and phosphorus 50.00% less than the positive control diet, 3) Negative control diet with 1.00 g kg^-1 Rovabio^® Plus multi-enzyme and 4) Positive control diet with 1.00 g kg^-1 Rovabio^® Plus multi-enzyme. The results showed that negative control diet caused a significant decrease in the egg production percentage, egg weight, egg mass, settable eggs, fertile eggs, hatchability and one grade chickens, increased the feed conversion ratio and embryonic losses. Addition of 1.00 g kg^-1 of multi-enzyme to negative control diet made the above parameters similar to the positive control treatment, however, the positive control treatment supplemented with multi-enzyme had a better performance compared to other treatments. This research showed that dietary supplementation of Rovabio^® Plus multi-enzyme in broiler breeders at the age of 45 - 60 weeks led to the improvement of productive performance and incubation in negative control diet.

Abstract Among global concerns about antibiotic resistance, it is necessary to identify food-safe alternatives to enhance production. This study aimed to evaluate the impact of mannan oligosaccharides (MOS) inclusion to replace antibiotic growth promoters (AGP) in the diets of ISA Brown laying hens aged between 23 and 31 weeks. Two hundred forty hens were grouped into five treatments: Control, AGP (130 ppm of enramycin 8.00%), and 100, 200, and 400 ppm of MOS. Each treatment had 16 experimental units (each unit with n = 3) in a randomized block experimental design. Productive data (egg production %, feed intake, egg weight), egg quality variables (albumin height, yolk weight, albumin, yolk %, weight eggshell, eggshell %, equator thickness, width-pole thickness, and Haugh units), organ weights (ovary, liver, and cecum) and jejunal histomorphometry were analyzed. The egg production was not affected by the substitution of AGP by MOS. Furthermore, MOS supplementation resulted in significantly increased feed intake, larger egg weight, higher yolk weight and higher body and ovarium weight compared to the AGP group. Besides, MOS supplementation at 400 ppm demonstrated significant improvements in jejunal villus morphology indicating enhanced intestinal health. These findings highlighted the potential of MOS as an alternative to AGP, offering benefits such as improved feed intake, egg quality and intestinal health in laying hens at 400 ppm.

Abstract Japanese quail (Coturnix coturnix japonica) is a popular experimental animal model in scientific research. The present study investigated the effects of dietary multiple enzyme supplementation on growth performance, carcass characteristics, nutrient digestibility and small intestinal histomorphology in quails fed diets based on wheat and soya bean meal. A total number of 192 1-day-old quails were assigned to three treatments with 16 replicates in each and four quails per replicate for 38 days.  The control group received a basal diet, and the treatment groups received a basal diet with 0.10 or 0.20% multi-enzyme, respectively. Growth performance parameters, carcass characteristics, nutrient digestibility and small intestinal histomorphology in quails were evaluated. Dietary supplementation of multi-enzymes to diet significantly increased body weight gain and improved the feed conversion rate. Moreover, quails fed with 0.10 or 0.20% multi-enzymes showed better ash digestibility coefficients and apparent metabolizable energy coefficients than the control quails. Furthermore, quails fed on a diet containing 0.20% multi-enzyme had the highest crude fiber digestibility. The villi length and the villi length/crypt depth ratio of the duodenum were significantly increased and the crypt depth was decreased in quails-fed diets supplemented with both multi-enzyme levels. However, feed consumption, carcass yield, carcass weight, heart weight, gizzard weight, liver weight and total intestine weights were not affected by treatments. In conclusion, our results showed that dietary supplementation of multi-enzymes to a wheat and soybean meal-based diet enhanced the growth performance and nutrient digestibility of quails.

Abstract Whole soybeans serve as one of the main sources of protein in ruminant nutrition. Different processing methods have been employed for ruminal protein protection. The present study was conducted to determine the effects of microwave irradiation [900 W; 2, 4 and 6 min] on quality, ruminal degradability and estimated in vitro intestinal digestibility of availability soybean crude protein. This experiment was performed in a completely randomized design with seven treatments including control (no processing), along with 2, 4 and 6 min of microwave irradiation on whole and ground soybeans. Protein and carbohydrate fractions were determined according to Cornell Net Carbohydrate and Protein System (CNCPS). Triplicates of the samples were incubated in the rumen of three cannulated Holstein steers for up to 48 hr. Microwave irradiation increased neutral detergent insoluble nitrogen, metabolizable protein content and resulted in a lower effective rumen degradability and in vitro gas production. Nevertheless, longer processing time led to higher unavailable protein and carbohydrate fractions. In the main, microwave irradiation of ground samples for 4 min increased metabolizable protein content, without negative effects on protein and carbohydrate availability.

Abstract The aim of this experiment was to investigate rumen fermentation and some blood parameters of dromedary camels fed with C₃ and C₄ forage. Four fistulated dromedary adult camels were fed with diets as a changeover design, 30 days for each period. The diets included alfalfa hay + wheat straw (C₃ forage) and atriplex+ suaeda + seidlitzia (C₄ forage). At the end of the experiment, rumen and blood parameters, gas production of wheat straw and atriplex as a 2 × 2 factorial experiment were determined. The highest blood glucose and urea nitrogen levels were found for camels fed with C₃ forage, 2 hr after feeding (p < 0.05). The maximum NH₃-N concentration in the rumen was for diets C₃ and C₄, 2 and 4 hr after feeding (p < 0.05). The lowest rumen pH was observed for C₃ diet at 2 and 4 hr and for C₄ diet at 4 and 8 hr after feeding. The activity of rumen carboxymethylcellulase (CMCase) and microcrystalline cellulase (MCCase) enzymes was the highest for C₃ and C₄ diets, 8 hr after feeding, however, during feeding the enzyme activity in C₄ was higher than that of 2 hr (p < 0.05). The rumen volatile fatty acid (VFA) concentrations were significantly higher in camels fed C₃ forage in comparison with C₄ (p < 0.05). The results showed that the gas production potential was significantly higher in treatments containing atriplex, however, the gas production rate was higher in treatment containing wheat straw (p < 0.05). The results suggested that for camels maintained in closed systems, the replacement of C₃ forages instead of C₄ could be possible and useful.

Abstract This experiment was conducted to investigate the effects of olive leaf (OL) on the performance, abdominal fat pad and some ileal bacterial population of Cobb broiler chickens. A total number of 400 day-old chicks were randomly distributed into floor pens and reared under the same condition until 14 days of age. On day 14, each pen was randomly assigned to one of the five experimental treatments with four replicates of 20 male and female chicks. The dietary treatments were consisted of a control group which fed basal diet without OL entire period of the study and groups 2 to 5 that fed diets supplemented with 0.25, 0.50, 0.75 and 1.00% OL powder, respectively. On days 21 and 42 of the experiment, ileal digesta samples were collected under the sterile condition to evaluate ileal bacterial population. The results indicated that birds fed diets containing various levels of OL, had higher body weight gain (except for 1.00% OL) and lower feed conversion ratio compared to that of the control group. Dietary inclusion of OL resulted in a higher count of Lactobacillus sp.  compared to the control group on 42 days of age, while Escherichia coli count significantly was not influenced. The abdominal fat pad was lower in birds fed OL supplemented diets. In conclusion, findings of the current experiment showed that the OL had positive effects on feed conversion ratio, abdominal fat pad deposition and ileal bacterial count of broiler chickens.

Abstract This study was conducted to investigate the effects of recycled poultry bedding (RPB) treated with different levels of pomegranate peel extract (PPE) as a tannin source on cellulolytic bacterial population and rumen fermentation parameters of fattening lambs. For this purpose, twenty-eight Arabian lambs (19.70 ± 2.45 kg body weight, 90 ± 12 days of age) were randomly assigned to four dietary treatments. Recycled poultry bedding was treated with PPE at four levels of 0 (control), 20.00, 25.00 and 30.00% on DM basis. Bacterial populations were enumerated by DNA extraction of samples of rumen liquor followed by real-time polymerase chain reaction analysis. Also, rumen samples were evaluated for pH, volatile fatty acid (VFA) and ammonia nitrogen (AN) concentrations. The populations of total bacteria, Ruminococcusalbus and Fibrobacter succinogenes were decreased significantly as the level of PPE in the diet increased, however, the population of Ruminococcus flavefaciens was not affected. Dietary treatments did not have effect on ruminal pH, while AN concentration was decreased in the diets containing RPB treated with PPE compared to the control. Concentrations of total VFA and individual VFA remained unchanged by PPE-treated RPB inclusion in the diet. In conclusion, supplementing RPB with PPE improved nitrogen metabolism of fattening lambs, however, it decreased population of rumen cellulolytic bacteria R. flavefaciens.

Abstract This study was conducted to determine the chemical composition and nutritive value of sunflower residues silage (SRS) and effects of its substitution with alfalfa hay and corn silage on lactation performance, feed intake, nutrient digestibility and some blood parameters of Mohabadi dairy goats. Four experimental diets were formulated to gradually replace alfalfa hay and corn silage with SRS as follows: Control (no inclusion of SRS, group 1) and groups 2 to 4, representing 15, 30 and 45.00% replacement of common forages in the diet with SRS, respectively. Sixteen multiparous dairy goats weighing 60.00 ± 3.00 were divided into two 4 × 4 latin square design. Ensiling was being able to increase crude protein content, reduce neutral detergent fiber and increase acid detergent lignin in sunflower residues. Daily dry matter (DM) intake and DM and organic matter (OM) digestibility decreased with increasing levels of SRS in the diet. The highest and the lowest digestibility coefficients belonged to 30 and 45.00% embedment levels, respectively. Milk yield decreased with increasing levels of SRS and differences were statistically significant compared to the highest substitution level. Milk composition was similar among diets, but daily production of milk decreased in higher substation levels. Statistically significant differences were found in serum low-density lipoproteins (LDL) concentrations between treatments and LDL levels decreased as dietary levels of SRS increased. According to these results, SRS is an acceptable feed for dairy goats and common dietary forages can be replaced up to 30.00% with SRS without negative effects on milk yield and composition.

Abstract The aim of this study was to evaluate the feeding of Qizil fattening lambs with different levels of broiler litter (BL) on their weight gain, dry matter intake (DMI), nutrient digestibility, selected blood metabolites and husbandry economics. During an eight-weeks experimental period, 28 male lambs (an average of 42.21 ± 5.63 kg and ages of 7-8 months) were allocated randomly to one of four dietary treatments, including; control diet with no litter (NL, n = 7), diet containing 5% BL (LL, n = 7), diet with 10% BL (ML, n = 7) and diet containing 15.00% BL (HL, n = 7) as dry matter (DM) basis. The lambs were kept in individual pens and had free access to feed and water (ad libitum) throughout the study. In this research, DMI and feed conversion ratio were not influenced significantly by the dietary treatments, while average daily gain (ADG) was found to be significant. The lambs which consumed LL diet (5.00% BL) had the greatest ADG. The DM digestibility significantly influenced by dietary treatments, as the HL diet (15.00% BL) had the least DM digestibility. There were also significant differences in the crude protein and acid detergent fiber digestibility among the treatments. Blood urea nitrogen and glucose levels were significantly affected by the treatments. Low litter treatment had the least FCR and the highest economical advantage. In conclusion, feeding male Qizil lambs with BL can reduce production cost without any negative effects on performance.

Abstract The purpose of this study was to investigate the effect of different corn processing methods on rumen microbial flora, histomorphometry and fermentation in fattening male lambs. Twenty male lambs (average age and weight of 90 days and 25.00 ± 1.10 kg, respectively) were used in a completely randomized design including four treatments and five replicates each over 80 days long period: 1) Lambs fed ground corn seeds; 2) Lambs fed steam-rolled corn; 3) Lambs fed soaked corn seeds (24 hr) and 4) Lambs fed soaked corn seeds (48 hr). At the end of the experiment, three lambs of each treatment were slaughtered and samples were collected for pH, volatile fatty acids, amylolytic, proteolytic, cellulytic and heterophilic bacteria and protozoa assessment. The number of proteolytic bacteria in soaked corn seeds was significantly increased in comparison with other treatments. The thickness of wall, papillae and muscular layers of rumen in the soaked corn seeds treatment was significantly increased. Overall, from a practical point of view, soaked corn processing could be generally used in lambs fattening system.

Abstract Indigestible neutral detergent fibers (iNDF) accurately predict forage digestibility when measured in situ. The objective of this study was to determine the effects of rumen incubation times on the estimated concentrations of iNDF for four forages (alfalfa hay, corn silage, wheat straw and orchard grass), four concentrates (barley grain, soybean meal, beet pulp and wheat bran) and two total mixed ration samples in dairy cows. The iNDF contents of the samples were evaluated in 10 feeds using three ruminally cannulated Holstein cows in a completely randomized design. Five grams of the samples were incubated up to 240 hr. The iNDF fraction was significantly affected by incubation time for all of the tested samples, but the potentially digestible NDF fraction (pdNDF) was not affected for wheat straw, barley grain and wheat bran (32.32, 10.11 and 20.60 g per 100 g of dry matter, respectively). For most of concentrates feedstuffs, the iNDF fraction could be measured after 120 hr of incubation, while for forages ruminal incubation should be lasted up to 240 hr. Statistically significant differences (p < 0.01) were observed between forage samples regarding fragility and NDF digestibility (NDFD). Also, a positive correlation was observed between fragility and NDFD. In some of the cases, it appears that NDFD can be a more helpful index in adjusting pdNDF values than direct fragility measurements.

Abstract The present experiment was conducted to evaluate the effects of organic acids and phytase enzyme supplementation on performance and intestinal histomorphology of broilers. The experiment was done in a factorial arrangement 2 × 2 × 2 based on completely randomized design with eight treatments, five replicates with 12 chicks in each until 42 days of age. Diets included natural vinegar (0 and 2%), citric acid (CA; 0.00 and 1.00%) and phytase enzyme (PHY; 0.00 and 500 FTU phytase per kg of feed). One bird from each treatment replicate was randomly selected and slaughtered to evaluate the small intestinal morphology on 42 days of age. Analysis of results showed that vinegar increased feed consumption and body weight gain in total experimental period (p ˂ 0.05), while CA significantly decreased feed consumption on 0-14 days of age (p ˂ 0.05). No effect was observed on performance in interaction of organic acids together and with PHY group (p > 0.05). In duodenum CA increased the villusheight and width (p ˂ 0.05) and PHY enzyme increased villuswidth (p ˂ 0.05) and decreased crypt depth (p ˂ 0.05). On the other hand, CA along with PHY significantly decreased crypt depth (p ˂ 0.05). In jejunum PHY alone and in combination with vinegar increased the goblet cells numbers (p ˂ 0.05), whereas vinegar significantly increased the goblet cells numbers in ileum (p ˂ 0.05). The muscular thickness in duodenum, jejunum, and ileum was not affected among different treatment groups. The results showed that supplementation of organic acids and phytase together in this experiment, with no negative effects on each other, improved their effects on some parameters.

Abstract The aim of this study was to evaluate the effects of adding sulfuric acid to sugarcane topssilage on rumen bacteria and whole rumen microorganisms (WRM) and compare the digestibility of sugarcane tops treated with different amount of urea, molasses and sulfuric acid between Holstein cow and Khouzestan buffalo. Regardless of the type of the treatment, potential of gas production (B) by cow WRM (130.670 mL) was more than buffalo (104.060 mL) (p < 0.05), but the rate of gas production (C) by buffalo WRM was greater than cow (0.021 and 0.014 mL per hr, respectively) (p < 0.05). The C in treatment containing only 2.40% sulfuric acid (0.033 mL per hr) was significantly highest (p < 0.05). Regardless of the type of the treatment, the B by cow rumen bacteria (75.040 mL) was more than buffalo (67.150 mL), (p < 0.05), while the C by rumen bacteria of buffalo (0.030 mL per hr) was more than cow (0.017 mL per hr), (p < 0.05). Regardless of the type of the animal, the B coefficient of rumen bacteria in treatment only containing 2.40% sulfuric acid was higher than control (p < 0.05). Therefore, the addition of sulfuric acid not only had no negative effect on microorganisms particularly bacteria, but also probably due to present of sulfur in acid, had positive effect on nutrients digestibility, and growth of microorganisms. The digestibility of sugarcane tops silage treated by cow rumen bacteria and whole microorganisms was higher than buffalo.

Abstract The present study was conducted to evaluate the effect of fish oil supplementation prior to mating on secondary sex ratio of pups (the proportion of males at birth) in bitches. Sixty five bitches (German Shepherd, n = 35; Husky, n = 30) were enrolled in the study. Bitches (140-150 days post-estrus) were given 2% per dry matter intake palm oil and fish oil in the control (n = 33) and treatment (n = 32) groups, respectively. To induce estrus, bitches were received equine chorionic gonadotropin (eCG) administration (50 IU kg^-1) 30 days after nutritional supplementation followed by human chorionic gonadotropin (hCG) administration (500 IU per dog) seven days later. Bitches were introduced to dogs of the same breed after hCG administration. The weight of bitches was increased over time (p < 0.05), but their weight change was not different between two groups (p > 0.05). The mating rate, pregnancy rate and litter size were not influenced by treatment and breed. Secondary sex ratio was higher in the treatment (105/164; 64.00%) than in the control (68/147; 46.30%) group (p < 0.05; adjusted odds ratio = 2.068). Moreover, secondary sex ratio was higher in Husky bitches (88/141; 62.40%) compared to German Shepherd (85/170; 50.00%; p < 0.05; adjusted odds ratio = 1.661). In conclusion, the present study showed that inclusion of fish oil in the diet of bitches prior to mating could increase the proportion of male pups at birth. In addition, it appears that there might be variation among dog breeds with regard to the sex ratio of offspring.