Partial Replacement of Noug Seed Cake with Brewery Grain and Linseed Cake to Mitigate Aflatoxin in Dairy Cattle Concentrate Feed

Abstract

The study was undertaken to minimize aflatoxin level of dairy cow concentrate feed by blending aflatoxin more susceptible feed ingredient (noug seed cake) with aflatoxin less susceptible feed ingredient (brewery grain and linseed cake) to reduce the aflatoxin levels in feeds and milk. The study was carried out at Holetta dairy research station using 15 mid lactating F1 Boran x Friesian crossbred dairy cows having parities of 1-5 and average weight of 450 kg. Cows were fed three diets: Treatment 1 = native hay + noug seed cake (40%) + wheat bran (58%) + salt (2%); Treatment 2 = native hay + wheat bran (42%) + brewery grain (36%) + noug seed cake (20%) + salt (2%); Treatment 3 = native hay + wheat bran (58%) + linseed cake (20%) + noug seed cake (20%) + salt (2) using Randomized Completely Blocked Design (RCBD. The feed ingredients and compound concentrate mixtures were examined for aflatoxin groups vis: aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2). Milk samples were analyzed for aflatoxin M1 (AFM1), aflatoxin M2 (AFM2), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2) following the standard procedures described for analysis of aflatoxin using High Liquid Chromatography (HPLC). The results revealed that, the aflatoxin level of feeds (AFB1) of native hay and dried brewery grain was found to be zero (0 μg/kg AFB1). Wheat bran, noug cake, noug cake based concentrate mixture, brewery grain based concentrate mixture had moderate AFB1 levels of 5.25μg/kg, 3.45μg/kg, 1.12μg/kg and 4.09μg/kg respectively. Cows supplemented brewery grain based concentrate feed had the lowest level of AFM1(0.31μg/L) as compared to milk of cows supplemented noug seed cake based concentrate feed (0.43μg/L) and that of milk of cows supplemented linseed cake based concentrate feed (4.58μg/L). Cows that fed brewery grain based concentrate feed supplement had relatively higher feed intake (14.7  0.05 kg), higher daily milk yield (9.1  0.09 L), better milk fat (3.91 ± 0.18), higher milk total solids (12.62 ± 0.17) and better daily weight gains (0.34 ± 0.01), as compared to the conventional feed supplement which resulted feed intake (13.8  0.05kg); daily milk yield (8.1  0.09L); milk fat (3.87 ± 0.18%); milk total solids (12.33 ± 0.19%); and daily weight gain (0.24  0.01kg) and linseed cake based concentrate feed supplement which resulted in feed intake (14.1  0.07kg); daily milk yield (7.7  0.1L); milk fat (3.71 ± 0.16%)and milk total solids (12.61 ± 0.18%). Therefore, dried brewery grain based concentrate feed supplement should be considered and be utilized as an important dairy feed supplement, as it provides dual benefits of minimizing aflatoxin levels and contributes to better milk production in dairy cows. Further studies should focus on aflatoxin investigation of linseed cake that is prepared from freshly harvested grain.