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).

A comparison between different concentrations and sources of cobalt in goat kid nutrition.

There have been extensive studies in sheep and cattle considering cobalt (Co) supplementation and its effects on vitamin B12 concentrations in the body. However, there are limited studies on goats. The aim of this study was to compare two different sources of Co (sulfate v. glucoheptonate) at two different concentrations (0.25 and 0.5 mg/kg dry matter) in goat kid nutrition, and to evaluate the effects of these supplements on performance, serum vitamin B12, blood biochemistry and rumen volatile fatty acids. For this purpose, 30 weaned male goat kids were randomly allotted to five treatments. Serum vitamin B12 increased during the trial in the Co-supplemented groups. Co supplementation increased serum glucose concentrations. On day 35, Co-supplemented groups had greater glucose concentrations compared with control. Propionic+iso-butyric acid concentrations increased only in the 0.5 mg Co glucoheptonate treatment (P<0.05). Our results suggest that, despite the two sources of Co proving mostly similar, the main advantage of Co glucoheptonate compared with Co sulfate was in the ruminal synthesis of vitamin B12. However, although providing Co at National Research Council recommendation levels maintained vitamin B12 above or at normal concentrations, Co supplementation of the Co sufficient basal diet increased vitamin B12 and glucose concentrations.

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.

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.