Abstract
In an experiment conducted on 34 mid-lactation dairy cows of the Red-and-White and Black-and-White breed, in a random square design, the effect of maize or sorghum-maize silage present in partly mixed ration (PMR) on milk yield, milk composition and blood serum parameters was investigated. The PMR diet contained maize silage, which compared with PMR diet contained sorghum-maize silage made from strip-cropped plants. Both fodder plants were harvested with a 4-row precision chopper, which cut 2 rows of maize and 2 rows of sorghum, giving mixed maize/sorghum forage. The feeding experiment lasted 84 days and consisted of four sub-periods, each 21 days in length to record milk yield, feed and milk chemical composition, and blood parameters. In addition to PMR diets containing part of ration compound feedingstuffs, the cows received part of compound feedingstuffs given at feed stations to meet their nutritional requirement. The compound feedingstuffs in station were controlled by an electronic system related to actual cow's milk yield. Chemical composition of both silages and milk production efficiency were compared. The average dry matter intake in both groups was 18.80 vs 20.4±1.95 kg/day, but compound feedingstuff intake from station was 3.61 vs 4.56 (P>0.01). Milk yield was 21.8 and 20.5±0.51 kg/day, respectively (P>0.01). The amount of standardized fat and protein content of milk (FPCM) was 21.0 and 20.2 kg/g ±0.48 kg/day (P≥0.01). No significant differences were found in the fat, protein, casein, lactose, urea, total solids and solids not fat percentage of milk or in milk traits (acidity, renneting time, density) among groups (P≥0.01). Feeding cows PMR ration with maize silage significantly elevated total cholesterol (P<0.05), but decreased urea levels in blood plasma (P<0.01). It is concluded that strip cropping of sorghum and maize could be an alternative to maize grown as a pure stand in maize high-risk areas for dairy cows in mid-lactation.