Abstract:
The aim of the study was to determine the effect of different inclusion levels of palm kernel
expeller (PKE) in dairy concentrates for grazing Jersey cows on lactation performance and
rumen fermentation patterns. Forty-eight multiparous, Jersey cows, grazing kikuyu-ryegrass
during spring, were blocked according to 4% fat corrected milk, days in milk and lactation
number 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) treatment
concentrates was 0, 200, and 400 g/kg, respectively, and was fed for a 60 d period, preceded
by a 21 d adaptation period. The PKE partially substituted some of the maize and soybean in
the concentrate. Additionally, eight rumen-fistulated, lactating dairy cows were randomly
allocated 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 and
20.7 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 not
differ between cows on all treatments. Total volatile fatty acid, mean ruminal pH, ammonia
nitrogen, and in situ pasture dry matter and neutral detergent fibre degradability did not differ
between cows on all treatments. The acetic to propionic acid ratio was higher (P=0.006) for
cows receiving treatment HP compared to cows receiving treatment C (3.40 vs. 3.22). It was
concluded that PKE can sustain milk yield and milk fat components at a level of up to 400
g/kg of concentrate when fed at 6 kg/cow/d to cows grazing kikuyu-ryegrass pasture. A more
practical recommendation might be to limit PKE to 200 g/kg of concentrate due to potential
palatability problems and a slow rate of intake when fed during milking in the parlour.
