In vitro evaluation of aflatoxin B1 effect on gas production and ruminal fermentation parameters.

BACKGROUND: Aflatoxins are fungal secondary metabolites negatively affecting ruminant performance; however, little information is available on their impact on rumen fermentation. AIMS: This study aimed at determining the effects of different concentrations of aflatoxin B1 (AFB1) from Aspergillus flavus on in vitro gas production and ruminal fermentation parameters using two experiments (Exp.). METHODS: In Exp. 1, two concentration ranges (0, 0.5, 1, and 1.5 µg/ml of rumen inoculum as low and 0, 5, and 10 µg/ml as high concentration ranges) were used to evaluate AFB1 effect on gas production kinetics using 96-h incubations. In Exp. 2, only the high concentration range was used to investigate AFB1 effects on ruminal fermentation parameters using 24-h incubations. RESULTS: In the low concentration range, the half-time of asymptotic gas production (T1/2) increased and the fractional rate of gas production (µ) decreased linearly with AFB1 dosage (P<0.05). However, in the high concentration range, the asymptotic gas production (A) and T1/2 decreased; and the lag time (L) and "µ" increased linearly (P<0.001) by increasing the concentrations of AFB1. In Exp. 2, dry matter (DM) and organic matter (OM) disappearance, microbial biomass (MB) and total volatile fatty acids (TVFA) concentrations were depressed, but pH and ammonia-N concentration increased (P<0.01) by increasing the concentrations of AFB1. The pattern of rumen volatile fatty acids (VFAs) was also modified by AFB1, as the propionate proportion increased at the expense of acetate. CONCLUSION: Aflatoxin B1 had an adverse effect on in vitro ruminal fermentation parameters in high concentration ranges (5 and 10 µg/ml).

Effect of dietary fibres on small intestine histomorphology and lipid metabolism in young broiler chickens.

Two experiments were conducted to determine the influence of dietary fibres on small intestine histomorphology and lipid metabolism in broilers from 1 to 21 day of age. In experiment 1, diets containing insoluble [cellulose (CEL); 2% and 4%] or soluble [carboxymethyl cellulose (CMC); 2% and 4%] fibre were fed to broilers from day 1 to 21 post-hatch and ileal tissue was collected at day 21 of age for histological evaluation. In experiment 2, broilers diet was supplemented with 0%, 1% or 2% insoluble fibre (Arbocel) during day 7 to 21 post-hatch and plasma and liver lipid metabolism were evaluated at day 21. In experiment 1, inclusion of CMC reduced body weight gain (BWG) and feed intake (FI) and increased feed conversion ratio (FCR) compared with others. Intestinal histomorphology was unaffected by CEL, but CMC led to an increase in crypt depth (CD) and serosa thickness and a decrease in villus height (VH), villus width (VW), VH:CD ratio and villus surface area (VSA), rather than control and CEL groups. Treatment did not affect goblet cell type. Moreover, the CMC-fed birds had greater total goblet cell count (GCC) as compared with others. In experiment 2, fibre inclusion was associated with increases in BWG from 7 to 14 day of age and an improvement in FCR, whereas FI was not influenced by treatments. Inclusion of fibre in the diet decreased the weight of the abdominal fat and cholesterol concentrations of liver and plasma. No significant effects on fatty acid composition of liver lipid were observed by fibre supplementation. These findings suggest dietary fibre affects performance, intestinal histomorphology and lipid metabolism in young chicks, which may directly affect poultry feeding strategies.

Effects of in ovo injection of bovine lactoferrin before incubation in layer breeder eggs on tibia measurements and performance of laying hens.

There is increasing concern about welfare of laying hens in cages, and one aspect of this topic relates to bone fragility. Therefore, bone anabolic components such as bovine lactoferrin (bLF) may be an effective strategy to maintain the integrity and health of bones. A total of 1080 eggs were divided into four groups with three replicates, each comprising 270 eggs; (1) control group was injected with 100 µl of normal saline per egg; (2, 3 and 4) groups including 22.5 (low), 45 (medium) and 67.5 µg (high) of bLF in 100 µl of normal saline per egg. Eggs were incubated and after hatching, chicks were reared to 28 weeks of age. Tibia measurements were obtained at hatch and at 28 weeks of age. Tibia weight at hatch, was not influenced by in ovo injection of bLF in comparison with the control. Eggs injected with the high concentration of bLF (67.5 µg of bLF per egg) showed significant strengthening in laying-hen tibias at 28 weeks of age, as measured by ultimate force and bending stress, compared with the control. Egg weights from hens treated with this concentration of bLF were also significantly greater than the control. Our data suggest that tibia cortical thickness is a suitable variable for evaluating bone status reflecting bone integrity and strength. The present study also shows that bLF (67.5 µg of bLF per egg) injected into layer breeder eggs before incubation can be used to improve bone strength and egg weight of laying hens at 28 weeks of age, while having no detrimental effect on embryo hatchability.

Effect of Dietary Cation-Anion Difference during Prepartum and Postpartum Periods on Performance, Blood and Urine Minerals Status of Holstein Dairy Cow.

Twenty four periparturient cows were used to determine the effects of DCAD on acid-base balance, plasma and urine mineral concentrations, health status, and subsequent lactation performance. Each group of 12 cows received either a diet containing -100 DCAD or +100 DCAD for 21 d prepartum. Both anionic and cationic groups were divided into two groups, one received a +200 DCAD and the other +400 DCAD diet for 60 d postpartum. Prepartum reduction of DCAD decreased DMI, urinary and blood pH, urinary concentrations of Na or K and increased plasma and urinary Ca, Mg, Cl and S. Also cows fed -100 DCAD diet consumed the most dry matter in the first 60 d after calving. Postpartum +400 DCAD increased milk fat and total solid percentages, urinary and blood pH and urinary Na and K concentrations, but urinary Ca, P, Cl and S contents decreased. Greater DMI, FCM yields were observed in cows fed a diet of +400 DCAD than +200 DCAD. No case of milk fever occurred for any diets but feeding with a negative DCAD diet reduced placenta expulsion time. In conclusion, feeding negative DCAD in late gestation period and high DCAD in early lactation improves performance and productivity of dairy cows.

Performance and egg quality of laying hens affected by different sources of phytase.

Ninety hens were divided into six groups as a 2 x 3 factorial design and fed diets containing Wheat Bran (WB) at two levels of 0 and 5% and the enzyme phytase at three levels of 0, 150 and 300 FTU kg(-1). Egg weight, egg production, feed intake and Feed Conversion Ratio (FCR) were determined. Eggs were collected on two consecutive days at fortnightly intervals to measure egg size and egg component weights. Shell thickness was measured. Egg production, egg weight, FCR and feed intake were not affected by WB. Egg production, egg weight and feed intake were significantly higher in phytase-supplemented groups than unsupplemented groups. FCR differed significantly between dietary treatments as phytase supplementation significantly decreased FCR. Inclusion of WB to the diets had no effect on egg size and albumen weight. Phytase supplementation did not affect yolk weight, although albumen and shell weight were significantly affected.

Decreasing broiler crude protein requirement by methionine supplementation.

The experiment was conducted with two levels of protein (23 and 20% in starter, 20 and 18% in grower) and three levels of methionine (NRC, 110 of NRC and 120% of NRC in starter and grower stages). No significant differences were found for protein, methionine or their interaction on Feed Intake (FI) and Feed Conversion Ration (FCR) for starter and grower, with the exception of an interaction of 20% CP and 0.46% (120% ofNRC) methionine which significantly improved (p < 0.05) the FCR compared with 18% CP and 0.38% (NRC) level ofmethionone, at the grower stage. Carcass yield and breast meat were significantly (p < 0.05) increased by 23% Crude Protein (CP) compared to 20% in starter. In contrast, abdominal fat was significantly decreased (p < 0.05) by 23 and 20% CP diet in starter and grower, respectively compared to the other levels of CP as well as by high levels of methionine. In the interaction of 20% CP and high level of methionine (0.46%) on carcass yield, a significant increase (p < 0.05) was found in grower stage compared with 18% CP and both 0.38% and 0.42% (110% of NRC) of methionine levels. A similar effect was found on breast meat yield compared with interaction of both 0.5% (NRC) and 0.55% (110% of NRC) of methionine and 20% CP at 21 days, as well as at 42 days of age with 0.38% methionine and 18% CP. Finally, the results of this study, have suggested that methionine/CP ratio could be adjusted at 0.024% (0.024 g methionine/per g crude protein) in starter and 0.023% for grower. Decreased CP in the diet, increased breast meat yield and reduction of abdominal fat were achieved by these ratios of methionine/protein.

Effect of different sources and levels of zinc on egg quality and laying hen performance.

Eighty layer hens were assigned in a completely randomized design to four dietary treatments containing zinc sulphate or organic zinc as Albino-Zn in two levels of 25 or 50 ppm. Feed intake was expressed on a per hen basis. Daily egg collection was expressed on a hen-day basis. Eggs were weighed to calculate egg mass. Feed conversion ratio was calculated as feed consumed per egg mass. Also all eggs produced on days 14, 28 and 42 were collected and used for egg quality parameters. Albumen height was measured and HU was calculated. The yolk and dried shell were weighed then albumen weight was calculated. There was no effect of zinc source or zinc level on egg production, egg weight or feed conversion ratio. However, feed intake was lower in the group receiving 50 mg kg(-1) organic zinc. There were no significant treatment differences for weight of egg components or shell thickness, but albumen height and HU were higher in the second fortnight for the groups receiving organic zinc at 25 or 50 mg kg(-1) than in the un-supplemented group.

Intestinal function and reproductive capacity of Tegel pullets in response to exogenous oestrogen.

The effects of varying levels of exogenous oestrogen (E2) (0, 10 or 100 micrograms E2/kg BW) on the development of 18-week old pullets were tested over a 28-day period. The hormone had no significant effects on feed intake, body growth, feed conversion ratio or weight of the oviduct. Similarly, there were no significant effects of the hormone on egg production and egg weight but eggshell thickness and weight of shell per unit area were increased (P < 0.05) at a lower level of administration (10 micrograms E2/kg BW), compared to the control and the highest level of hormone. The morphometry of the jejunal mucosa and some enzymes associated with Ca transport were similar between the three groups. Oestrogen treatment, however, intensely enhanced the expression of calbindin D22K, although this was not quantified.