Kamel Z. Mahmoud

Influence of selenium sources on age-related and mild heat stress-related changes of blood and liver glutathione redox cycle in broiler chickens (Gallus domesticus)

Selenium is an essential trace element that up-regulates a major component of the antioxidant defense mechanism by controlling the bodys glutathione (GSH) pool and its major Se-containing antioxidant enzyme, glutathione peroxidase (GPX). Evidence has emerged suggesting that organic selenium, natural seleno-amino acids found in plants, grains and selenized yeast, maintains the antioxidant defense system more efficiently than inorganic selenium. Inorganic selenium is a pro-oxidant, whereas organic selenium possesses antioxidant properties itself. As a pro-oxidant, inorganic selenium is not suitable for animals or humans. Therefore, we examined the GSH-GPX system in broiler chickens and determined that organic selenium was indeed more beneficial than inorganic selenium. Chickens fed the organic selenium as Sel-Plex, a selenized yeast, had elevated GPX activity in both blood and liver in a thermoneutral environment and after heat distress. More importantly, the ability to reduce the oxidized glutathione (GSSG to 2 GSH) was enhanced and facilitated by maintenance of glutathione reductase activity. Organic selenium-fed chickens were less affected by mild heat distress than inorganic selenium-fed chickens, and this assessment was based upon less induction of heat shock protein 70 (hsp70) in organic selenium-fed chickens. Our results clearly show that heat distress, a potent inducer of oxidative stress and hsp70, can be partially ameliorated by feeding organic selenium. We attribute this observation to an enhanced GSH-GPX antioxidant system in organic selenium-fed chickens.

Decay of maternal antibodies in broiler chickens

The objective of this study was to determine the decay rate of maternal antibodies against major broiler chicken pathogens. A total of 30 one-day-old broiler chicks were obtained from a commercial hatchery and reared in isolation. These chicks were retrieved from a parent flock that received a routine vaccination program. Chicks were bled at hatch and sequentially thereafter every 5 d through 30 d of age. Maternal antibody titers were measured by ELISA for avian encephalomyelitis (AEV), avian influenza virus (AIV), chicken anemia virus (CAV), infectious bursal disease virus (IBDV), infectious bronchitis virus (IBV), infectious laryngotracheitis virus (ILTV), Mycoplasma gallisepticum (MG), Mycoplasma synoviae (MS), and reovirus (Reo). Maternal antibody titers for Newcastle disease virus (NDV) were measured using a hemagglutination inhibition test. Half-life estimates of maternal antibody titers were 5.3, 4.2, 7, 5.1, 3.9, 3.8, 4.9, 4.1, 6.3, and 4.7 d for AEV, AIV, CAV, IBDV, IBV, ILTV, MG, MS, NDV, and Reo, respectively. The statistical analysis revealed significant differences among half-lives of maternal antibody titers against certain pathogens. Furthermore, all maternal antibody titers were depleted by 10 d of age except for IBDV.

Breeder age affects small intestine development of broiler chicks with immediate or delayed access to feed.

1. The relationship between breeder age and chick gastrointestinal tract development to 21 days of age, as influenced by immediate or delayed access to feed, was examined in three consecutive trials. 2. Ross 708 chicks, derived from breeder flocks at 31 (young), 40 (middle) and 63 (old) weeks of age were placed randomly into either a control group with immediate access to feed and water, or a 48 h feed delayed (FD) group with free access to water. 3. FD negatively affected body weight (BW) of chicks derived from young and old flocks through the first and second weeks of age, respectively. Chicks from the older flock absorbed more yolk in the first 48 h with no FD effect. When feed was made available, chicks from the FD group showed a large increase in small intestine weight relative to BW, surpassing (P < 0·05) the control groups across all breeder flock ages. 4. Morphological measurements in all intestinal sections had higher values in chicks derived from the middle age breeder flock. FD to newly hatched chicks from the young breeder flock shortened villi (P < 0·01), decreased crypt depth and villus surface area (P < 0·001) in the duodenum through the first week post hatch. 5. Crypt depths were maximised between 7 and 14 d post-hatch in chicks from young and old breeder flocks, but crypt depths in chicks from the middle aged flocks continued to deepen. 6. The increased crypt depth may augment the number of enterocytes available for villus growth, and facilitate longer villi and greater villus surface area, in chicks from the middle age flocks. Intestinal morphological variation was associated with breeder flock age, which accounted for differential growth in chicks derived from young, middle, and old aged breeder flocks.

Small intestinal histology, production parameters, and meat quality as influenced by dietary supplementation of garlic ( Allium sativum) in broiler chicks

Four hundred day-old male hatchling chicks were obtained from the female line of Lohmman grandparent stock farms and fed rations supplemented with different levels (0%, 0.25%, 0.50%, 1.0%) of dried garlic powder. Each treatment consists of 5 pens. Feed and water were provided as ad libitum throughout the experimental period. Production parameters measured were body weight, feed consumption, feed conversion ratio. Final body weight and feed conversion ratio were not affected (P>0.05) by garlic supplementation. However, feed consumption was the lowest (P<0.05) at 0.5% and 1%. Small intestinal histological measurements were influenced (P<0.05) by garlic powder supplementation. In duodenum, villus length was the highest (P<0.05) in birds fed with diets containing 1% garlic powder, and villus and epithelial width were the highest (P<0.05) in chicks fed with diets containing 0.5 percentage of dried powder. In jejunum, the villus length was the highest (P<0.05) in birds fed with diets containing 0.25% and 1% garlic powder, while villus and epithelial width were the lowest (P<0.05) in chicks fed with diets containing 0.5% of dried powder. Carcass traits were not affected (P>0.05) by garlic supplementation. All meat quality parameters measured were not affected (P>0.05) by garlic powder supplementation (cooking loss percentage, shear force, lightness, redness and yellowness), except for juiciness percentage and pH, which were the lowest (P<0.05) at 1.0% and 0.25%, respectively. As a conclusion, this study shows that garlic at a 0.5% level might be of beneficial effect on intestinal morphymetry parameters, as well as on production parameters.

The effects of Saccharomyces cerevisiae supplementation on intake, nutrient digestibility, and rumen fluid pH in Awassi female lambs

Aim: The aim of this study was to evaluate the effect of feeding low (LO)- or high (HI)-fiber diets supplemented with Saccharomyces cerevisiae (SC) on nutrient intake, digestibility, nitrogen balance, rumen fluid pH, and serum concentrations of glucose and urea nitrogen in Awassi female lambs in a 2×2 factorial arrangement of treatments. Materials and Methods: Experimental diets were as follows: (1) LO-fiber diet with no SC supplementation (−LO), (2) LO-fiber diet supplemented with SC (+LO), (3) HI-fiber diet with no SC supplementation (−HI), or (4) HI-fiber diet supplemented with SC (+HI). Eight female lambs were used in a replicated 4×4 Latin square design with 15-day experimental periods (10-day adaptation period and 5-day collection period). Results: A fiber×SC interaction (p≤0.05) was detected for dry matter (DM) and crude protein (CP) intake among diets showing greater DM and CP intake for +LO diet compared to +HI group supplemented with SC, whereas −LO and −HI were intermediate. A fiber×SC interaction (p=0.05) was also detected for the neutral detergent fiber (NDF) intake among diets. Intake of NDF was greater for the –HI diet compared with +LO and –LO diets. Similarly, NDF intake was greater for +HI diet than –LO diet. A tendency (p=0.07) for a fiber×SC interaction was detected for acid detergent fiber (ADF) intake among diets as well. ADF intake tended to be greater for HI-fiber diets. No difference was observed in the rumen fluid pH for lambs fed with the different diets. No fiber×SC interactions were detected for the digestibility of DM, CP, NDF, and ADF among dietary treatments. Digestibility of DM was greater (72.9 g/100 g vs. 67.1 g/100 g; p=0.0002) for LO versus HI fiber. However, NDF and ADF digestibilities were greater (60.8 and 61.9 g/100 g vs. 55.8 and 52.7 g/100 g for NDF and ADF digestibility, respectively; p≤0.01) for the HI-fiber than the LO-fiber diets. Conclusion: Results obtained in the current study indicate that SC supplementation has a minimal effect on the performance of Awassi female lambs fed with varying fiber levels.