Physiology

This study was intended to explore the oxidative status of broilers under cyclic heat stress (HS) as modulated by supplementation of mannan-oligosaccharides (MOS) and a probiotic mixture (PM). Two hundred fifty 1-d-old chicks were randomly divided into 5 groups. From d 22, birds were either kept in a thermoneutral zone (TN; 26.7°C for 24 h/d) or subjected to HS (35 ± 1.1°C and 75 ± 5% RH for 8 h/d from 1000 to 1800 h) to the conclusion of the study on d 42. Birds were fed either a corn-based diet (TN and HS groups) or the same diet supplemented with 0.5% MOS (HS-MOS group), 0.1% PM (HS-PM group), or their combination as a synbiotic (SYN; HS-SYN group). On d 42, birds were killed by cervical dislocation to collect serum for the determination of total oxidants, total antioxidants, paraoxonase, arylesterase, ceruloplasmin, aspartate aminotransferase, alanine aminotransferase, and trace minerals. Heat stress increased (P < 0.05) total oxidants and total antioxidants and decreased (P < 0.05) paraoxonase and arylesterase, with no change in ceruloplasmin, aspartate aminotransferase, and alanine aminotransferase activities. Dietary supplementation decreased (P < 0.05) total oxidants and total antioxidants, with no effect on the activities of other enzymes. Heat stress did not influence serum copper, zinc, and manganese concentrations of birds when compared with those in the TN group. However, MOS increased (P < 0.05) concentrations of all the trace minerals, whereas SYN increased (P < 0.05) concentrations of only zinc and copper. It was concluded that MOS or PM supplementation, alone or as a SYN, may reduce some of the detrimental effects of HS, whereas MOS alone or as a SYN may improve the absorption of trace minerals.

The present study was aimed at elucidating the effects of supplementing mannan-oligosaccharides (MOS) and probiotic mixture (PM) on growth performance, intestinal histology, and corticosterone concentrations in broilers kept under chronic heat stress (HS). Four hundred fifty 1-d-old chicks were divided into 5 treatment groups and fed a corn-soybean diet ad-libitum. The temperature control (CONT) group was held at the normal ambient temperature. Heat stress broilers were held at 35 ± 2°C from d 1 until the termination of the study at d 42. Heat stress groups consisted of HS-CONT fed the basal diet; HS-MOS fed the basal diet containing 0.5% MOS; HS-PM fed the basal diet containing 0.1% PM; and HS-SYN (synbiotic) fed 0.5% MOS and 0.1% PM in the basal diet. Broilers were examined at d 21 and 42 for BW gain, feed consumption, feed conversion ratio (FCR), serum corticosterone concentrations, and ileal microarchitecture. The results revealed that the CONT group had higher (P < 0.01) feed consumption, BW gain, and lower FCR on d 21 and 42, compared with the HS-CONT group. Among supplemented groups, the HS-MOS had higher (P < 0.05) BW gain and lower FCR compared with the HS-CONT group. On d 21 and 42, the HS-CONT group had higher (P < 0.05) serum corticosterone concentrations compared with the CONT and supplemented groups. The CONT group had higher (P < 0.05) villus height, width, surface area, and crypt depth compared with the HS-CONT group. On d 21, the HS-PM had higher (P < 0.05) villus width and surface area compared with HS-CONT group. On d 42, the HS-SYN had higher (P < 0.05) villus width and crypt depth compared with the HS-CONT group. These results showed that chronic HS reduces broiler production performance, intestinal microarchitecture, and increases adrenal hormone concentrations. Also, supplementation of the MOS prebiotic and the PM can partially lessen these changes.

The study was conducted to evaluate the potential cryoprotective effect of butylated hydroxytoluene (BHT) through post-thaw evaluation of canine semen and its optimal inclusion level. Ejaculated canine semen was extended in TRIS-glucose egg yolk extender containing various concentrations of BHT (0.5, 1.0, 1.5, 2.0, and 2.5mM). Semen was frozen at −196°C using 200 × 10 6 spermatozoa per 0.5 ml straws and post-thaw evaluation was carried out in terms of sperm motility, viability, plasma membrane integrity, and acrosomal integrity through phase-contrast microscope, supravital staining, hypo-osmotic swelling test, and normal acrosomal ridge, respectively. BHT was found to improve (P > 0.005) all post-thawed semen quality parameters at an inclusion level of 1.0mM in the extended semen. However, higher concentrations than this were found to have detrimental effects.

This study was designed to evaluate the effect of dietary supplementation of prebiotics, mannanoligosaccharides (MOS) and/or probiotics (LBP) on intraepithelial lymphocytes (IEL) count, goblet cells (GC) count and differentiation and intestinal micro-architecture in broilers reared under cyclic heat stress. Day-old broilers (n = 250) were randomly divided into five groups. Fifty birds were reared within the thermoneutral zone (TNZ). Remaining birds were subjected to cyclic heat stress from day 21 to 42 (35°C, 75% RH, 8 h/d). The birds were fed cornsoy-based basal diet or the same diet supplemented with 0.5% MOS (HS-MOS), or 0.1% LBP (HS-LBP), or their combination (HS-SYN). The birds were slaughtered on day 42. Tissue samples were collected from midduodenum, jejunum and ileum, and stained with haematoxylin and eosin or combined Alcian blue and PAS technique. All differences were considered significant at p < 0.05. The IEL count increased in all intestinal segments of the HS group compared with the TNZ group and decreased in all supplemented groups compared with the HS group. Compared with the TNZ, heat stress reduced villus height, crypt depth and surface area in duodenum and ileum, and increased crypt depth in ileum. Villus width decreased in duodenum and jejunum compared with the TNZ group. Supplementation of LBP, MOS and SYN reversed all these changes in duodenum, while only increased villus height and surface area in ileum. In jejunum, the villus height and surface area increased with HS-LBP, and crypt depth increased with HS-MOS. The number of GC containing acid mucins (duodenum and ileum) and mixed mucins (ileum) were increased in the HS compared with the TNZ. Supplementation of MOS, LBP and SYN maintained the enhanced activity of goblet cells. In conclusion, dietary supplementation of MOS and/or LBP may be helpful in alleviating some of the detrimental effects of heat stress on microstructure of the broiler gut.

Heat stress (HS), one of the major problems of tropical and subtropical countries, adversely affects the production performance of poultry. Keeping this in view, the present study was designed to investigate some of the biological markers of HS in broilers as modulated by dietary supplementation of mannan-oligosaccharide (MOS) and a Lactobacillus-based probiotic (LBP), either alone or in combination. Two hundred fifty 1-d-old-chicks were randomly divided into 5 groups. From d 22, the birds were either kept at the thermoneutral zone (TN) or exposed to HS to the conclusion of study, d 42. Birds were fed either a corn-based basal diet (TN and HS groups) or the same diet supplemented with 0.5% MOS (HS-MOS group), 0.1% LBP (HS-LBP group), or their combination. Birds were immunized against Newcastle disease virus on d 4 (intraocular; live attenuated) and d 20 (drinking water; live attenuated) and infectious bursal disease virus on d 8 (intraocular; live intermediate strain) and d 24 (drinking water; live attenuated). Birds were killed on d 42 to collect serum for determination of cortisol, thyroid hormones, cholesterol, C-reactive protein, and postvaccinal antibody titers. Results revealed that dietary supplementations decreased (P < 0.05) the serum cortisol and cholesterol concentrations and increased (P < 0.05) thyroxine concentration compared with the HS group without affecting triiodothyronine concentration. The percentage of the C-reactive protein-positive birds was higher (P < 0.05) in the HS group compared with the TN group. Dietary supplementations improved humoral immunity against Newcastle disease virus and infectious bursal disease virus during HS. In conclusion, dietary supplementation of either MOS or LBP alone or in combination can reduce some of the detrimental effects of HS in broilers.

The strains of Newcastle disease virus (NDV) were isolated from five suspected outbreaks of ND in broiler (n = 3) and layers (n = 2) poultry farms. The eggisolated viruses were subjected to biological and genetic characterization. Based on the biological characterization, isolates showed haemagglutination titer Clog 2 7 , mean death time \55 h, intracerebral pathogenecity index B1.8, and egg lethal dose 50 from 10 -7.15 to 10 -9.31 /1 ml. Genetic characterization of the fusion (F) gene revealed that the isolates clustered with NDV strains of genotype VII (VIIf) within class II, which remained predominant genotype in the domestic poultry of Asia. The deduced amino acid sequence of the isolates confirmed virulent motif 112 RRQKRF 117 at the F protein cleavage site. A bioinformatics and pairwise comparison approach was applied to estimate the synonymous and non-synonymous substitution rates (dN/dS) and selective evolutionary pressure for the F protein. The dN/dS calculated for genotype VII indicate purifying selection, which resulted in a low evolution rate in F gene. The F protein shows a strong negative pressure throughout the length of the protein and no recombination event was determined. Collectively, the results suggest that very similar virulent strains of NDV are involved during current wave of disease outbreak throughout the country. From these results, in conjunction with our recent reports of NDV from Pakistan, it is possible to conclude that emergence of novel group may require revisiting the diagnostics and vaccine control strategies.

A study was conducted to elucidate the effects of supplementation of mannan oligosaccharide (MOS), a prebiotic, and probiotic mixture (PM) on growth performance, relative weights (RW) of viscera, and population of selected intestinal bacteria to broilers reared under cyclic heat stress (HS). Two hundred fifty 1-d-old broiler chicks were randomly divided into 5 treatment groups with 5 replicates. From d 22 onward, the broilers were reared either in a thermoneutral zone (TN) or exposed to HS until d 42. Birds were fed either a corn-based basal diet (TN and HS groups) or the same diet supplemented with 0.5% MOS, 0.1% PM, or their combination as synbiotic. Birds were killed on d 42 to collect viscera and jejunal and cecal digesta. Digesta was used to enumerate Clostridium perfringens, total coliforms, and Escherichia coli. The HS decreased mean BW gain, feed consumption, and FE of broilers compared with the TN broilers. The TN group had higher RW of spleen, bursa of Fabricius, and ceca compared with the HS group. The supplementation of PM and SYN improved mean BW gain and FE compared with the HS group. Increase in RW of spleen, bursa, intestine, and ceca was observed in the supplemented groups compared with the HS group. Based on these findings, we concluded that HS has significant negative effects on mean RW of viscera and growth performance of broilers. Moreover, feeding a diet supplemented with either MOS or PM alone or as combination can partially or completely ameliorate these effects.

Canola oil and vitamin A were evaluated for their effects on egg characteristics, egg cholesterol and egg triglycerides (TG) in laying hens prone to heat-stress during summer months. Four levels of canola oil (0, 2, 3 and 4% of diet) in combination with two levels of vitamin A (3,000 or 10,000 IU/kg of diet) were fed to laying hens for a period of 12 weeks. Various egg-quality parameters were measured on weekly basis while, serum TG, egg cholesterol and TG contents were analyzed during the last week of the trial. The results of the study showed that the egg weight, egg mass, yolk weight, Haugh unit score, shell thickness, shell weight and egg breakingstrength were similar (P>0.05) for all canola oil levels supplemented to the laying hens. Higher egg weight and egg mass (P<0.05) were noted for the hens at the diet with 10,000 IU vitamin A /kg of diet whereas, all other egg characteristics were not influenced by increasing the supplemental level of vitamin A. Serum TG, egg cholesterol and TG contents were not changed (P>0.05) by increasing canola oil or vitamin A levels in the diet of laying hens. It might be concluded from the results of the present study that canola oil as a source of omega-3 fatty acids can be included in the diet of laying hens without compromising the quality characteristics of the eggs. ©2013 PVJ. All rights reserved To Cite This Article: Ahmad S, AU Haq, M Yousaf, Z Kamran, AU Rehman, MU Suhail and HA Samad, 2013. Effect of canola oil and vitamin a on egg characteristics and egg cholesterol in laying hens during hot summer months. Pak Vet J, 33(3): 346-349.

Newcastle disease (ND) is one of the most deadly diseases of poultry around the globe. The disease is endemic in Pakistan and recurrent outbreaks are being reported regularly in wild captive, rural and commercial poultry flocks. Though, efforts have been made to characterize the causative agent in some of parts of the country, the genetic nature of strains circulating throughout Pakistan is currently lacking.

The impact of maternal flock age and incubation on embryo metabolism was studied to understand late incubation overheating and mortality in Ross 308 embryos. Fresh broiler hatching eggs (n = 45) were obtained from commercial breeder flocks at 3 ages: Young (Y): 25 to 34 wk, Peak (P): 35 to 45 wk, Old (O): 46 to 54 wk of age), stored for 2 to 4 d at 18°C and 73% RH, then incubated for 14 d at 37.5°C and 56% RH. At 15 d of incubation (E15), 12 fertile eggs per flock age were placed individually in metabolic chambers and subjected to one of 4 machine temperatures (MT; 36.0, 36.5, 37.0, or 37.5°C) until E21.5. The O 2 consumption, CO 2 production and eggshell temperatures (EST) were recorded and embryonic heat production (EHP) calculated and used as an indicator of embryonic metabolism. At E21.5, quality was assessed using chick weight, length, pipping and hatching times. Data were analyzed by the Proc Mixed procedure of SAS at P < 0.05 significance level. Relation ships among MT, parent flock age, EHP and EST were determined by regression. There were no differences in daily O 2 consumption, CO 2 production or EHP between maternal flock ages or MT. Daily EST was not affected by flock age. The EST at 37.5°C was higher than all other MT treatments except at E20 where it was not different from 37.0°C MT. The daily EST at 37.0°C MT was also higher than the daily EST at 36.5°C and 36.0°C, while 36.5°C had higher daily EST compared with 36.0°C MT. The MT showed a strong positive linear relationship with EST (R 2 = 0.89) but there was no relationship between EST and EHP. Egg weight and chick weight increased as flock age increased. There was no effect of flock age on chick length or pipping time but hatching time was shorter for 37.0°C MT compared with all other temperatures. In conclusion, MT had a much greater effect on embryo development than maternal flock age in Ross 308 embryos. Key Words: breeder flock age, incubation temperature, heat production, eggshell temperature, chick quality 88 Effect of hen age and late incubation temperature on bone development of Ross 308 broiler chicks. Key Words: breeder flock age, incubation temperature, breaking strength, bone mineralization 89 Effect of incubation temperature profile on broiler foot pad dermatitis. M. J. Poult. Sci. 92(E-Suppl. 1) 94 Precision broiler breeder feeding system improved body weight uniformity. M.

The mode of action of essential oils (EO) as growth promoters is not fully understood. One experiment was conducted to evaluate the effects of EO concentration and grain type on broiler intestinal traits. Corn (C) and wheat (W) based basal diets were formulated to have similar nutrient composition within each dietary phase. The EO containing benzoic acid (Crina Poultry Plus) was added to each basal diet to have 0, 150, or 300ppm. Starter, grower, and finisher diets were fed from 0-14d, 15-35d, and 35-47d, respectively. At hatch, 720 Ross 708 male broilers were identified and placed in 72 floor pens. At the end of each dietary phase one broiler per pen was selected, sacrificed and the length of intestines, the weights of pancreas, duodenum, jejunum, and ileum, and the pH of the proximal duodenum contents were determined. Mucus digesta content was quantified using a colorimetric procedure. Data were analyzed as a 2x3 factorial design with grain type and EO concentration as main factors. Results indicated an interaction effect (P < 0.05) on pH at 47d, with EO increasing pH in chickens fed W diets, and reducing it in broilers fed C diets. Less mucus was observed in 47d chickens fed diets with 300ppm EO than in diets without EO. An interaction effect (P ≤ 0.05) was observed at 35d with less mucus in the C diets than in W diets at 300ppm EO. At 14 and 47d, the pancreas relative weight (RW) was bigger (P < 0.05) in C than in W. At 14d the pancreas RW was larger (P < 0.05) in chickens fed 300ppm EO than in those without EO, and at 47d pancreas RW of broilers from 150ppm diets was bigger than diets without EO. At 35d, the intestine was shorter in chickens fed 300ppm diets than fed 0 and 150ppm diets. At 47d, the intestine was longer in chickens fed C diets compared with W diets. At all collections, C chickens had bigger (P < 0.05) ileum RW than W. In general, the EO increased pancreas size, reduced intestinal length, and reduced mucus production, while C diets caused increased pancreas RW and intestinal length compared with W diets. It was concluded that EO may affect intestinal development and function with different effects depending on grain type.

The present study aims at evaluating the effects of dietary supplementation of prebiotics or probiotics alone or in combination on growth performance, relative-weight of viscera, mucosal microarchitecture and some selected intestinal microbiota in broilers reared under hot humid conditions. Day-old broilers (n = 250) were randomly divided into 5 groups. Birds in the control group were reared under standard management conditions and fed a corn-based basal diet without any dietary supplementation. The birds exposed to cyclic-heat stress (35°C and 75%RH, 8hr/d, 1000-1800 h from d22 to 42), were fed a basal diet (HS group) alone or supplemented with 0.5% mannan-oligosaccharides (MOS), or 0.1% Lactobacillus-based probiotics (LP) or combination of both (symbiotic). On d 42, 15 birds from each group were killed to determine relative-weights of visceral organs, mucosal morphometry and numeration of jejunum and cecal Clostridium perfringens, coliform and E. coli. The data were analyzed using ANOVA. Results revealed that heat stress decreased (P < 0.01) body weight gain, feed conversion ratio (FCR) and relative weights of organs compared with the control group. Dietary supplementations increased the FCR (P < 0.05), relative weights of spleen (P < 0.01), small intestine (P < 0.01) and cecum (P < 0.01) compared with HS group. However, supplemented diets did not affect the relative weights of bursa of Fabricius (P = 0.07) liver, pancreas, gizzard and heart. Heat stress increased the cecal population of coliform, (P < 0.05) Clostridium perfringens (P < 0.01) and E. coli (P < 0.05) compared with control group without affecting the jejunal (P = 0.61) bacterial count. Supplementation of MOS alone or probiotics reduced (P < 0.05) the cecal count of Clostridium perfringens. The villus height was more (P < 0.05) in supplemented groups compared with the HS group. In conclusion, supplementation of prebiotics and probiotics is a good tool for maintaining production performance of broilers during hot humid months.

Mammalian spermatozoa experience osmotic stress when the glycerol is added to the cells before freezing and removal from the cells after thawing. To minimize osmotic damage, alternative cryoprotectants, having lower molecular weights and greater membrane permeability than glycerol, were evaluated to determine their effectiveness for cryopreserving bull spermatozoa. The primary goal of this study was to compare glycerol as the most common cryoprotectant of bull spermatozoa to ethylene glycol and methyl as alternative cryoprotectants. Bull semen was diluted with tris-egg yolk extender containing 3% glycerol, 3, 2 and 1% ethylene glycol and 3, 2 and 1% methyl. Bull semen was frozen in pellets form using the cold surface of cattle fat. Computer assisted sperm analysis (CASA) assay was used to study the post-motility properties of bull spermatozoa. Bull spermatozoa exhibited higher percentages (P < 0.01) of all motile spermatozoa properties when frozen in extender containing 3% glycerol compared with 3, 2 and 1% ethylene glycol or 3, 2 and 1% methyl cryoprotectants. It is concluded that glycerol concentrations of 3% in the extender is the most suitable cryoprotectant for cryopreservation of bull spermatozoa.

People usually have fundamentally incorrect notions about bacteria. Only a few people know that some bacteria have a positive influence upon our health apart from making goose bumps all over body. There are several microbes harboured by our intestine, which benefit us by stimulating the digestive system and protecting against diseases.

The present study was conducted to evaluate the effects of feeding whole linseed on the laying performance and egg characteristics in laying hens kept at high ambient environmental temperatures (average 34 ºC; the diurnal temperature range 26 ºC to 41 ºC). Two hundred and forty 38-wk-old white Leghorn laying hens were fed diets containing 0, 5, 10 or 15% whole linseed (as a source of n-3 polyunsaturated fatty acids) for a period of 12 weeks. Egg production was recorded daily, while feed intake and egg characteristics were monitored on weekly basis. The results of the study demonstrated that egg production and feed intake decreased, while feed conversion ratio (FCR) per dozen of eggs increased (p ≤ 0.05) with increasing dietary linseed levels. Egg weight, yolk weight, albumen height, eggshell weight, and eggshell thickness were not influenced (p > 0.05) by linseed levels in the diets offered to the laying hens. The results of the present trial suggest that feeding linseed to the laying hens in hot climates has no detrimental effects on egg characteristics, but has suppressive effects on egg production, feed intake and feed efficiency of laying hens. Ahmad S, Ahsan-ul-Haq, Yousaf M, Kamran Z, Ata-ur-Rehman, Sohail MU, Shahid-ur-Rahman