Impact of age on hepatic cytochrome P450 of domestic male Camborough‐29 pigs

Swine is not only an important species in veterinary medicine research but also a popular animal model for human drug discovery. It is valuable to understand the impact of pig age on abundance and activity of porcine hepatic cytochrome P450 (CYP450). Liver microsomes were prepared from Camborough‐29 intact male pigs at the age of 1 day and 2 weeks and the castrated male pigs at the age of 5, 10, and 20 weeks. Hepatic CYP450 content in the liver microsomes was measured using a UV/visible spectroscopic method. The activities of CYP450s were evaluated by metabolism of phenacetin, coumarin, tolbutamide, bufuralol, chlorzoxazone, and midazolam. The porcine hepatic CYP450 content increased with age with a plateau between age 2 and 5 weeks. Activities of all CYP450 enzymes increased with age of pigs too. The bufuralol 1’‐hydroxylase showed the highest hepatic activities compared with other CYP enzymes at all ages of pigs. The average activities at the age of 20 weeks were about five times higher than those at the age of 5 weeks for most of the CYP enzymes. With compensation of the ratio of liver to body weights, the overall CYP450 metabolism capability of the pigs may be peaked around ages of 10 to 20 weeks. Those findings suggest that metabolism can be significantly different in growing phase of pigs and that the age may be an important factor in porcine medicine evaluation and pig model development.     

Age, genotype and sex effects on growth performance of local chickens kept under improved management in Ghana

Characterisation of animal genetic resources has been recognised globally as an important step towards their sustainable use. Body weight data of local chickens (213 forest and 160 savannah chickens) and 183 French free-ranging SASSO T44 chickens kept under improved management were collected from hatch to 40 weeks of age and analysed to determine the effects of age, genotype and sex on their growth performance. At all ages, SASSO T44 chickens had significantly (P < 0.05) higher weights (2.6–3.2 kg at 28 weeks) than the local chickens (1.2–1.7 kg at 28 weeks). The rate of growth at the earlier ages in the local genotypes (5.57–7.80 g/day) was lower than the range of 13.81–15.42 in SASSO T44 chickens. Except at hatch, savannah chickens were significantly heavier (P < 0.05) than the forest chickens at all ages. Male chickens had significantly (P < 0.05) superior growth rates than females across all genotypes except from the 20th to the 28th week. Growth trends in both sexes depicted linear increase in body weights; however, the rate of increase in body weights was higher in males as compared to females, thus showing clear sexual dimorphism. There were no significant (P > 0.05) differences in the growth rates of SASSO T44 chickens and local genotypes at the later ages (20–28 weeks). Local chickens from the savannah zone had better growth rate than forest chickens. The significant effect of ecozone on the growth potential of local chickens is an indication that their productive potential could be improved through interventions in the environment such as provision of feed and some veterinary care.     

Skatole Metabolism in the Pigs with Reduced Testicular Oestrogen Synthesis

The objectives of the study were to investigate the involvement of oestrogens in the regulation of skatole levels in pigs. In total, 44 intact male pigs, siblings from 10 litters, were included in the study. Pigs were orally treated weekly with either 0.1 mg letrozole/kg body weight to reduce endogenous oestrogens or the canola oil vehicle. Fat and liver samples were collected at slaughter at 16, 20 and 40 weeks of age. Skatole and androstenone levels in fat and activities of hepatic cytochrome P4501A1, CYP1A2, CYP2A19 and CYP2E1 were analysed. Letrozole treatment did not significantly change either the levels of skatole or activities of skatole‐metabolising enzymes, suggesting that oestrogens are not responsible for gender‐related differences in skatole concentrations in porcine tissues.     

Effects of epigallocatechin gallate on lipid metabolism and its underlying molecular mechanism in broiler chickens

The objective of this study was to investigate the effects of epigallocatechin gallate (EGCG) on fat metabolism and to establish the molecular mechanism of these effects in broilers. Seventy‐two 28‐day‐old male Ross 308 broiler chickens were divided into three groups with different levels of EGCG supplementation for 4 weeks: normal control (NC) group, L‐EGCG (a low‐level supplement of EGCG, 40 mg/kg body weight daily) and H‐EGCG (a high‐level supplement of EGCG, 80 mg/kg body weight daily). After 4 weeks of oral administration, EGCG significantly reduced the level of abdominal fat deposition in broilers. The serum triglycerides and low‐density lipoprotein cholesterol of chickens in H‐EGCG group were also significantly decreased compared with the NC group, and the high‐density lipoprotein cholesterol was notably increased at the same time. Moreover, the vital role of the liver and abdominal adipose tissue in lipid metabolism of poultry animals was examined through gene expression and enzyme activities related to fat anabolism and catabolism in these organs. Our data show that EGCG supplementation for 2 weeks significantly downregulated the expression of fatty acid synthesis and fat deposition‐related genes, and upregulated the expression of genes involved in fatty acid β‐oxidation and lipolysis genes. Simultaneously, the activities of hepatic fatty acid synthesis enzymes (fatty acid synthase and acetyl CoA carboxylase) were significantly decreased, and the activity of carnitine palmitoyl transferase‐1 was notably elevated. The results suggest that EGCG could alleviate fat deposition in broilers through inhibiting fat anabolism and stimulating lipid catabolism in broilers.     

Effects of delaying post‐hatch feeding on lipid peroxidation and antioxidant enzyme mRNA expression in the pectoralis major muscle of newly hatched chicks

Excessive lipid peroxidation negatively affects the physiological response and meat quality of chickens. Delaying post‐hatch feeding was previously found to increase lipid peroxidation in the skeletal muscle of finishing broiler chickens. The aims of this study were to investigate the effects of delayed post‐hatch feeding on lipid peroxidation and the mRNA expressions of antioxidant enzymes in the pectoralis major muscle of broiler chicks during the post‐hatching period. Newly hatched chicks either had immediate free access to feed (freely‐fed chicks) or had no access to feed from 0 to 2 days old (delayed‐fed chicks), after which both groups were fed ad libitum until 4 or 13 days old. The lipid peroxidation level was higher in the delayed‐fed than freely‐fed chicks at 2, 4, and 13 days old. At 2 days old, the mRNA expressions of Cu/Zn‐SOD, Mn‐SOD, and GPX7 were lower in the delayed‐fed than freely‐fed chicks, while catalase mRNA levels did not differ. Furthermore, at 4 and 13 days old, lower mRNA expressions of Cu/Zn‐SOD and Mn‐SOD were observed in the delayed‐fed than freely‐fed chicks. These results suggest that delaying post‐hatch feeding reduces the mRNA levels of Cu/Zn‐SOD and Mn‐SOD, consequently affecting muscle lipid peroxidation in chicks during subsequent growth.     

Tibiotarsus bone characteristics and tibial dyschondroplasia incidence of broilers fed diets supplemented with leucine and valine

Two experiments were conducted to study the effect of standardized ileal digestible (SID) leucine and valine levels on tibiotarsus bone characteristics and the incidence of tibial dyschondroplasia of broilers from day 1 to 21 (Experiment I) and day 21 to 42 post‐hatch (Experiment II). Each experimental phase was evaluated independently. In both experiments, a total of 1,500 one‐day‐old Cobb 500 male broiler chickens were distributed in a completely randomized design 5 × 5 factorial arrangement for a total of 25 treatments. The SID leucine and valine levels were ranged from 10.0 to 19.6 g/kg, and 6.0 to 12.0 g/kg from day 1 to 21 post‐hatch, respectively, while day 21 to 42 post‐hatch ranged from 10.0 to 18.0 g leucine/kg, and 5.2 to 11.2 g valine/kg. Serum calcium and phosphorus, bone concentrations of calcium, phosphorus and ash, diameter and Seedor index of the tibiotarsus were not affected (p > .05) by the treatments at 21 or 42 days of age. There was an interaction (p ≤.06) between the SID levels of leucine and valine on tibiotarsus breaking strength at 21 days, but not at 42 days of age (p > .05). Tibiotarsus breaking strength was maximized in broilers from day 1 to 21 with the dietary levels of leucine and valine at 14.2 and 9.0 g/kg respectively. Dietary leucine levels reduced linearly (p < .05) the hypertrophic zone of tibiotarsus cartilage at 21 days of age. Therefore, leucine and valine supplementation interact positively on bone strength of broilers from day 1 to 21 post‐hatch. Leucine can be a useful amino acid for reducing the hypertrophic cartilage zone in broilers from day 1 to 21, but not from day 21 to 42 post‐hatch.     

Gene expression differences in the methionine remethylation and transsulphuration pathways under methionine restriction and recovery with D,L‐methionine or D,L‐HMTBA in meat‐type chickens

This study examined the molecular mechanisms of methionine pathways in meat‐type chickens where birds were provided with a diet deficient in methionine from 3 to 5 weeks of age. The birds on the deficient diet were then provided with a diet supplemented with either D,L‐methionine or D,L‐HMTBA from 5 to 7 weeks. The diet of the control birds was supplemented with L‐methionine from hatch till 7 weeks of age. We studied the mRNA expression of methionine adenosyltransferase 1, alpha, methionine adenosyltransferase 1, beta, 5‐methyltetrahydrofolate‐homocysteine methyltransferase, 5‐methyltetrahydrofolate‐homocysteine methyltransferase reductase, betaine‐homocysteine S‐methyltransferase, glycine N‐methyltransferase, S‐adenosyl‐L‐homocysteine hydrolase and cystathionine beta synthase genes in the liver, duodenum, Pectoralis (P.) major and the gastrocnemius muscle at 5 and 7 weeks. Feeding a diet deficient in dietary methionine affected body composition. Birds that were fed a methionine‐deficient diet expressed genes that indicated that remethylation occurred via the one‐carbon pathway in the liver and duodenum; however, in the P. major and the gastrocnemius muscles, gene expression levels suggested that homocysteine received methyl from both folate and betaine for remethylation. Birds who were switched from a methionine deficiency diet to one supplemented with either D,L‐methionine or D,L‐HMTBA showed a downregulation of all the genes studied in the liver. However, depending on the tissue or methionine form, either folate or betaine was elicited for remethylation. Thus, mRNA expressions show that genes in the remethylation and transsulphuration pathways were regulated according to tissue need, and there were some differences in the methionine form.     

Influence of Campylobacter jejuni cecal colonization on immunoglobulin response in chickens

The immunoglobulin response of chickens to colonization by Campylobacter jejuni isolates B-540 and Clin-1 was monitored. Chicken humoral IgG and biliary secretory IgA (sIgA) responses were assessed by enzyme-linked immunosorbent assay (ELISA). Samples were taken from 128 C. jejuni-colonized chickens and 104 uncolonized chickens housed in a controlled environment. An indirect ELISA was performed using the homologous isolate of C. jejuni as the capture antigen and was developed with the specific goat anti-chicken IgG or IgA alkaline phosphatase conjugates. The ELISA absorbance values of the test samples at 405 nm (serum diluted 1:32 and bile diluted 1:10) were normalized in direct proportion to standard sera and bile sample values. In the colonized chickens, humoral IgG activities were highest at hatch, dropped to their lowest level after 2 weeks, and increased by 8 weeks to levels similar to those detected at hatch. The sIgA activity was lowest at hatch and increased by 4 weeks in colonized chickens while remaining lower in the control chickens. Chickens colonized with isolate B-540 showed a primary sIgA response during the first 4 weeks and reached a plateau over the final 4 weeks. In spite of these limited humoral and secretory immunoglobulin responses, once the chicken ceca was colonized by C. jejuni, the organism persisted throughout the 8-week experiment.     

Response of Thai indigenous crossbred chickens to various dietary protein levels at different ages

The objective of this study was to evaluate the protein requirement of Korat chicken (KRC), a slow-growing cross strain between the Thai indigenous fighting cock (Leung Hang Khoa) and the modern genotype females. Four periods were considered: from hatch to 21 days (phase 1), 22 to 42 days (phase 2), 43 to 63 days (phase 3), and 64 to 84 days of age (phase 4). A total of 3120 mixed-sex KRC were randomly allocated to 5 dietary protein levels containing 19, 20, 21, 22, and 23% with 2978 kcal of ME/kg (900 birds in phase 1); 18, 19, 20, 21, and 22% with 3151 kcal of ME/kg (780 birds in phase 2); 16, 17, 18, 19, and 20% with 3200 kcal of ME/kg (720 birds in phase 3); and 15, 16, 17, 18, and 19% with 3200 kcal of ME/kg (720 birds in phase 4) with 6 replicates in a completely randomized design. The results showed that BW, BW gain, average daily gain (ADG), and protein intake (P?<?0.05) were increased with increasing dietary protein (P?<?0.05) in all phases. However, FI, feed cost per kg of BW gain, energy intake, and blood urea nitrogen of chickens were not found to be significantly different among treatments. On the other hand, increasing dietary protein levels depressed the protein efficiency ratio of chickens from hatch to 21 and from 64 to 84 days of age (P <?0.05), and tended to decrease it from 22 to 42 (P?=?0.08) and from 43 to 63 (P =?0.07) days of age as well. According to a broken-line regression analysis, the protein requirements of chickens from hatch to 21 and from 22 to 42 days of age for maximum BW gain were 21.26 and 20.45%, respectively. While the requirements of maximum responses for BW gain and FCR in the period of 43 to 63 days of age were 18.00 and 18.04%, respectively, and in the period of 64 to 84 weeks of age were 17.94 and 18.03%, respectively.

     

Effect of dosage and application mode of l‐carnitine on plasma lipid and egg‐yolk cholesterol of turkeys,hatchability of eggs and post‐hatch growth of their offsprings

The effect of dosage and application mode of l ‐carnitine on plasma lipid and egg‐yolk cholesterol of breeder turkeys, hatchability of eggs and post‐hatch growth response was investigated using 180 breeder hens. The hens were assigned to six dietary treatments in a 2 × 3 factorial arrangements of two application modes of l ‐carnitine (diet and drinking water) supplemented at 0, 50 and 100 ppm (mg/kg or mg/l) levels, respectively. Each treatment was replicated five times with six hens per replicate. Dietary inclusion of 50 ppm l ‐carnitine showed the lowest (p < 0.01) plasma total cholesterol (TC) and low‐density lipoprotein concentration (LDL). Breeder hens offered 50 ppm l ‐carnitine with no regard to application mode recorded the highest (p < 0.01) plasma high‐density lipoprotein (HDL). Hens offered 50 and 100 ppm l ‐carnitine irrespective of application mode also showed reduced (p < 0.01) egg‐yolk TC concentration at 32 weeks of age. Dietary supplementation of 50 ppm l ‐carnitine for breeder turkeys recorded the lowest (p < 0.01) egg‐yolk triglyceride (TG) at 40 weeks of age. Hens offered 50 ppm l ‐carnitine irrespective of application mode recorded the highest (p < 0.05) hen‐day egg production. Incidence of dead‐in‐shell also reduced (p < 0.05) with increasing dosage of l ‐carnitine. Dietary supplementation of 50 ppm and oral application in drinking water of 100 ppm l ‐carnitine for breeder turkeys resulted in highest (p < 0.05) egg fertility. Offsprings from breeder hens fed diets supplemented with l ‐carnitine recorded no post‐hatch mortality. Highest (p < 0.05) post‐hatch final live weight and weight gain was obtained with poults obtained from hens fed diet supplemented with 50 ppm l ‐carnitine. In conclusion, dietary supplementation of 50 ppm l ‐carnitine for turkey hens showed improved serum lipid profile, egg fertility, reduced dead‐in‐shell, egg‐yolk cholesterol and resulted in improved post‐hatch growth performance.     

Suppression of IgA synthesis in chickens

Four different protocols were tested for the induction of IgA deficiency in chickens: (I) inoculation of anti-alpha intra-peritoneally (i.p.) on alternate days after hatching up to a period of three weeks; (II) bursectomy within 6 h and at 24 h after hatching; (III) in-ovo injection of anti-alpha on the 17th day of embryonation followed by bursectomy at 24 h of hatch and a single injection of anti-alpha i.p. on the day of hatching; (IV) as in III above but bursectomy within 6 h of hatch, followed by three further injections of anti-alpha on days 3, 10 and 34 after hatching. Treatment (I) produced temporary dysgammaglobulinemia during the period of treatment. Bursectomy at 24 h of hatch rendered 75% of the chicks IgA deficient up to four weeks of age. Early bursectomy within 6 h of hatch resulted in substantial improvement of IgA suppression. Such chicks, when tested at 4, 6 and 10 weeks of age, were found to be 81, 72 and 58.3% IgA deficient, respectively. With treatment (III) all the treated birds were IgA deficient at four weeks of age. However, as the birds grew older, IgA appeared in the serum so that at the age of 12 weeks only 27.3% were deficient. Treatment (IV) completely suppressed the IgA system of 13 out of 14 chickens. These chickens lacked both serum and secretory IgA as well as IgA-containing cells in their intestinal mucosa. Both IgG and IgM continued to be produced.     

Comparing the glucuronidation capacity of the feline liver with substrate‐specific glucuronidation in dogs

This study aimed to assess the overall glucuronidation capacity of cats, using prototypic substrates identified for human UDP‐glucuronosyltransferases (UGTs). To this end, Michaelis–Menten kinetics were established for the substrates using feline hepatic microsomal fractions, and results were compared with similar experiments carried out with dog liver microsomes. Cats are known for their low capacity of glucuronide formation, and UGT1A6 was found to be a pseudogene. However, functional studies with typical substrates were not performed and knowledge of the enzymology and genetics of other glucuronidation enzymes in felidae is lacking. The results of this study showed extremely low formation of naphthol‐1‐glucuronide (1.7 ± 0.4 nmol/mg protein/min), estradiol‐17‐glucuronide (<0.7 nmol/mg protein/min), and morphine‐3‐glucuronide (0.2 ± 0.03 nmol/mg protein/min), suggesting a lack of functional UGT1A6 and UGT2B7 homologues in the cat's liver. Dog liver microsomes were producing these glucuronides in much higher amounts. Glucuronide capacity was present for the substrates 17β‐estradiol (estradiol‐3‐glucuronide, 2.9 ± 0.2 nmol/mg protein/min) and 4‐methylumbelliferone (31.3 ± 3.3 nmol/mg protein/min), assuming that cats have functional homologue enzymes to at least the human UGT1A1 and probably other UGT1A isozymes. This implies that for new drugs, glucuronidation capacity has to be investigated on a substance‐to‐substance base. Knowledge of the glucuronidation rate of a drug provides the basis for pharmacokinetic modeling and as a result proper dosage regimens can be established to avoid undesirable drug toxicity in cats.     

Methyl donors dietary supplementation to gestating sows diet improves the growth rate of offspring and is associating with changes in expression and DNA methylation of insulin‐like growth factor‐1 gene

The study aimed to investigate the effects of maternal dietary methyl donors on the performance of sows and their offspring, and the associated hepatic insulin‐like growth factor‐1 (IGF‐1) expression of the offspring. A total of 24 multiparous sows were randomly fed the control (CON) or the CON diet supplemented with methyl donors (MD) at 3 g/kg betaine, 15 mg/kg folic acid, 400 mg/kg choline and 150 μg/kg VB₁₂, from mating until delivery. After farrowing, sows were fed a common lactation diet through a 28‐days lactation period and six litters per treatment were selected to be fed until at approximately 110 kg BW. Maternal MD supplementation resulted in greater birthweight (p < 0.05) and increased the piglet weights (p < 0.01) and litter weights (p < 0.05) at the age of day 28, compared with that in CON group. The offspring pigs in the MD group had greater ADG (p < 0.05) and tended to lower F:G ratio (p = 0.07) compared with that of CON group from day 28 to 180 of age. The offspring pigs from MD group had greater serum IGF‐1 concentrations and expressions of hepatic IGF‐1 gene and muscular IGF‐1 receptor (IGF‐1r) protein at birth (p < 0.05), and greater hepatic IGF‐1 protein (p = 0.03) and muscular IGF‐1r gene expressions (p < 0.05) at slaughter, than that from the CON group. Moreover, the methylation at the promoter of IGF‐1 gene in the liver of newborn piglets and finishing pigs was greater in the MD group than that of the CON group (p < 0.05). In conclusion, maternal MD supplementation throughout gestation could enhance the birthweight and postnatal growth rate of offspring, associated with an increased expression of the IGF‐1 gene and IGF‐1r, as well as the altered DNA methylation of IGF‐1 gene promotor.     

Effects of Supplementing Holstein Heifers with Dietary Melatonin during Late Gestation on Growth and Cardiovascular Measurements of their Offspring

The objective was to examine the effects of supplementing dams with dietary melatonin during late gestation on offspring growth and cardiovascular measurements. On day 190 of gestation, heifers (n = 20) were blocked by body weight and randomly assigned to one of two dietary treatments consisting of 20 mg of dietary melatonin per day [melatonin (MEL)] or no melatonin supplementation [control (CON)]. Dietary treatments were terminated on day 262 of gestation. At birth, calves were separated from their dams with no further treatments. Calf (n = 18) blood pressure, cortisol, nitrites and total antioxidant capacity were collected on weeks 0, 1, 2, 3 and 4 of age. Calf hepatic portal blood flow and concentrations of insulin‐like growth factor 1 were determined on weeks 0 and 4 of age. Calf body weight, abdominal girth, hip height and wither height increased (p < 0.05) with age. An age by treatment interaction (p < 0.01) was observed for calf body weight, which was increased at weeks 8 and 9 of age in calves born to MEL heifers compared to calves born to CON heifers. Pulse pressure, mean arterial pressure, absolute hepatic portal blood flow and blood flow relative to calf body weight were not different (p > 0.05) between treatments. A main effect of calf age (p < 0.05) was observed for concentrations of insulin‐like growth factor 1, which was decreased at week 4 compared to week 0. An age by treatment interaction (p < 0.05) was observed for cortisol, which was decreased at week 2 in calves from MEL‐treated dams compared to calves from CON‐treated dams. Early post‐natal growth was altered in offspring born to dams supplemented with dietary melatonin. This could lead to further foetal programming implications in conjunction with post‐natal development.     

Effect of sex steroids on expression of sulfotransferase 2B1 immunoreactive protein in primary cultured porcine hepatocytes

An excessive accumulation of androstenone (5α-androst-16-en-3-one) in pig adipose tissue is one of the two major contributors to the phenomenon of boar taint. High levels of adipose tissue androstenone have been related to a low rate of hepatic androstenone metabolism, which includes two stages: oxidative and conjugative. Sulfotransferases (SULTs), alongside with other specific enzymes, play the key role in the conjugative stage of androstenone metabolism. The present study investigated the mechanism regulating expression of sulfotransferase 2B1 (SULT2B1) immunoreactive protein using primary cultured pig hepatocytes as a model system. A specific objective was to determine whether the expression of pig hepatic SULT2B1 is regulated by the sex steroids; androstenone, testosterone and estrone sulphate. The study was performed on entire male pigs of a Large White (40%) × Landrace (40%) × Duroc (20%) cross-breed, average carcass weight 72.2 kg. The study shows that SULT2B1 immunoreactive protein expression can be induced by testosterone (final concentrations, 10 and 500 nM) and repressed by estrone sulphate (final concentration, 100 nM). Androstenone had no significant effect on SULT2B1 immunoreactive protein expression in the range of concentration, 10 nM to 1 μM. Time-courses (0 to 48 h) of steroid effects were investigated. The maximum effects of testosterone and estrone sulphate were observed in 24 h after the steroid treatments. This study provides direct evidence for involvement of sex steroids in the regulation of porcine hepatic SULTs.     

Effects of body condition score (BCS) on steroid‐ and eicosanoid‐metabolizing enzyme activity in various mare tissues during winter anoestrus

The objective of this study was to determine the activity of steroid‐ and eicosanoid‐metabolizing enzymes in horses with varying BCSs. The BCSs of twenty non‐pregnant, anoestrous mares were determined prior to euthanasia, and tissue samples were collected from the liver, kidney, adrenal gland, ovary and endometrium. Cytochrome P450 1A (CYP1A), 2C (CYP2C), 3A (CYP3A) and uridine 5′‐diphospho‐glucuronosyltransferase (UGT) activities were determined using luminogenic substrates. The MIXED procedure of SAS was used to test the effect of BCS on enzyme activity and differences between tissues. Activity of CYP1A in adrenals was increased (p ≤ .05) in BCS 5 versus BCSs 4 and 6. Activity of CYP1A in the liver was increased (p = .05) in BCS 4 versus BCSs 5 and 6. Activity of CYP1A was 100‐fold greater (p < .0001) in the liver than in the adrenal, ovary and kidney. Activity of CYP2C was 100‐fold greater (p < .0001) in the liver than in the adrenal, ovary and endometrium. Activity of CYP3A was only detectable in the liver. Activity of UGT in the kidney was decreased (p = .02) in BCS 4 versus BCSs 5 and 6. Activity of UGT was threefold greater (p < .0001) in the liver than in the kidney, whereas activity of UGT was ninefold greater (p < .0001) in the kidney than in the ovary and endometrium. In general, BCS did not alter the activity of steroid‐ and eicosanoid‐metabolizing enzymes in horses. However, tissue differences in these enzymes indicated abundant hepatic metabolism in horses, which is similar to other livestock species.     

Genetic parameter estimates for body weight in local Venda chickens

Genetic parameters were estimated for Venda chicken body weights at hatching, and at 4 weeks, 10 weeks and 21 weeks of age. A single-trait animal model with restricted maximum-likelihood procedures was used. Random effects were additive direct and maternal genetic, common environmental and error. The heritability estimates for direct effects were 0.36, 0.25, 0.41 and 0.22 for hatch, 4 weeks, 10 weeks and 21 weeks, respectively. The maternal effects were estimated at hatch and 4 weeks of age and were not present at later ages. Common environmental effects disappeared with increasing age. There was an antagonistic relationship between direct and maternal effects. The results show potential for genetic improvement of indigenous Venda chickens through selection. Maternal effects should be considered if selection is carried out at early ages.     

Comparative development of digestive organs,intestinal disaccharidases and some blood metabolites in broiler and layer‐type chicks after hatching

1. Body weight, digestive organ weights, and activities of disaccharidases (maltase and saccharase) activities were determined from day of hatch to 21 d of age in meat‐ and egg‐type chickens. Blood plasma was analysed for enzyme activities and metabolite concentration.

2. In meat‐type chickens food intake and growth rate were about 3‐fold those in egg‐type chickens. Food efficiency was superior in meat‐type chickens throughout the experimental period.

3. Meat‐type chickens hatched with disaccharidase activities exceeding those found in their egg‐type counterparts 2‐ to 5‐fold. From 7 d of age on, this trend reversed, i.e. activity was much higher in egg‐type than in meat‐type chickens.

4. Blood plasma amylase activity increased gradually in meat‐type chickens and was higher than in egg‐type chickens to 14 d of age. No breed differences were observed for alkaline phosphatase or lactate dehydrogenase activities during the experimental period.

5. Blood plasma concentrations of total protein, albumin, glucose, and calcium, were lower in meat than in egg‐type chickens.     

Effects of in ovo feeding of L‐arginine on the development of digestive organs,intestinal function and post‐hatch performance of broiler embryos and hatchlings

This study was to investigate the effects of in ovo feeding (IOF) L‐arginine (Arg) solution on the development of digestive organs, the duodenal mucosa of broiler embryos and hatchlings, and the growth performance of chicks during the first week post‐hatch. A total of 720 fertilized eggs with similar weight were randomly allocated to three groups, consisting of eight replicates of 30 eggs each. Three treatments were arranged as non‐injected control, diluent‐injected (0.75% NaCl solution) group and Arg solution‐injected group containing 1% Arg, dissolved in diluent. At 17.5 days of incubation, 0.6 ml of IOF solution was injected into amniotic fluid of each egg of injected groups. Results showed IOF of Arg solution increased (p < .05) the chick embryo weight at 19 days of incubation; the body weight gain of post‐hatch broilers during 1–7 days; the weights of liver, pancreas, proventriculus and gizzard; the concentrations of duodenal ghrelin, vasoactive intestinal peptide and glucagon‐like peptide 2; and the duodenum mucosal enzyme activities of alkaline phosphatase, maltase, sucrase and inducible nitric oxide synthase of 7‐day‐old post‐hatch broilers compared with other groups. The IOF of Arg solution also increased (p < .05) the villus height (VH) and the ratio of VH to crypt depth (CD) and decreased (p < .05) the CD in duodenum of broiler embryos and post‐hatch hatchlings, except for the CD at 19 days of incubation. In conclusion, IOF of 1% Arg solution into the amnion at 17.5 days of incubation could improve the development of digestive organs, the duodenal morphology, the releasing of gastrointestinal hormones and mucosal enzyme activities of broiler embryos and hatchlings and finally the growth performance of chicks during the first week post‐hatch. Therefore, IOF of appropriate Arg solution could be an effective technology for regulating early nutrition supply and subsequent growth development in poultry industry.     

Effects of in ovo injection of chrysin,quercetin and ascorbic acid on hatchability,somatic attributes,hepatic oxidative status and early post‐hatch performance of broiler chicks

An experiment was conducted to evaluate the effects of in ovo injection of chrysin, quercetin and ascorbic acid on hatchability, somatic attributes, hepatic antioxidant status and early post‐hatch growth performance of broiler chicks. Four hundred and eighty embryonated broiler breeder eggs containing live 18‐day‐old embryos were divided into six groups of 80 eggs each. One group remained intact and served as a control group (i), whereas the other five groups were injected with the prepared injection solutions as follows: (ii) 0.05 ml distilled water; (iii) 0.05 ml distilled water containing 6 mg ascorbic acid; (iv) 0.05 ml dimethyl sulfoxide (DMSO); (v) 0.05 ml DMSO containing 4.5 mg quercetin; and (vi) 0.05 ml DMSO containing 4.5 mg chrysin. The hatchability rate, hatching weight, residual yolk sac weight, yolk sac‐free body weight, liver weight, hepatic glutathione peroxidase and total superoxide dismutase activities, as well as malondialdehyde concentrations, were not affected by the injected solutions. There were no differences between chicks hatched from the control and in ovo injected eggs in weight gain, feed intake and feed conversion ratio from 0 to 11 days of age. However, the specific contrast performed between the in ovo injected groups and intact eggs revealed that in ovo injection significantly increased hatchability rate (p = .0493). This finding also implies that our injection procedure was harmless. In conclusion, the intra‐egg injection of chrysin, quercetin or ascorbic acid at the injection rates used in this study did not have a significant effect on hatchability, somatic characteristics, early growth performance and hepatic antioxidant status of broiler chicks. However, the overall hatchability was higher in the in ovo injected eggs as compared to non‐injected ones. These findings also confirmed the harmlessness of the procedure developed for in ovo injection in this study.