Effect of palm kernel expeller as supplementation on production performance of Jersey cows grazing kikuyu-ryegrass pasture

摘要

The aim of the study was to determine the effect of different inclusion levels of palm kernelexpeller (PKE) in dairy concentrates for grazing Jersey cows on lactation performance andrumen fermentation patterns. Forty-eight multiparous, Jersey cows, grazing kikuyu-ryegrassduring spring, were blocked according to 4% fat corrected milk, days in milk and lactationnumber and randomly allocated to three treatments based on PKE level in the concentrate.The PKE inclusion in the control (C), low PKE (LP), and high PKE (HP) treatmentconcentrates was 0, 200, and 400 g/kg, respectively, and was fed for a 60 d period, precededby a 21 d adaptation period. The PKE partially substituted some of the maize and soybean inthe concentrate. Additionally, eight rumen-fistulated, lactating dairy cows were randomlyallocated to the C and HP treatment in a two period cross-over design. Cows received 6 kg(as is) concentrate per day divided over two milkings and strip-grazed pasture as one group.Milk yield and milk fat content did not differ between treatments and were 21.3, 21.3 and20.7 kg/cow/d and 46.3, and 46.5, and 46.6 g/kg for the C, LP and HP treatment,respectively. Milk protein, milk urea nitrogen, body weight and body condition score did notdiffer between cows on all treatments. Total volatile fatty acid, mean ruminal pH, ammonianitrogen, and in situ pasture dry matter and neutral detergent fibre degradability did not differbetween cows on all treatments. The acetic to propionic acid ratio was higher (P=0.006) forcows receiving treatment HP compared to cows receiving treatment C (3.40 vs. 3.22). It wasconcluded that PKE can sustain milk yield and milk fat components at a level of up to 400g/kg of concentrate when fed at 6 kg/cow/d to cows grazing kikuyu-ryegrass pasture. A morepractical recommendation might be to limit PKE to 200 g/kg of concentrate due to potentialpalatability problems and a slow rate of intake when fed during milking in the parlour.