Palm kernel expeller increases milk fat content when fed to grazing dairy cows
Palm kernel expeller (PKE) is a feed by-product that is used by the dairy and beef industries. This study investigated the effect of partially replacing maize with PKE in a dairy concentrate on milk and ruminal fermentation parameters of Jersey cows grazing kikuyu-ryegrass pasture. Seventy-two multiparous cows were blocked according to milk yield, days in milk, and lactation number and randomly allocated within blocks to one of four treatment concentrates: PKE0, PKE10, PKE20, and PKE30, containing 0, 100, 200, and 300 g PKE/kg dry matter (DM), respectively. Eight rumen-cannulated lactating cows were used in a 4 x 4 Latin square design. All cows grazed pasture as one group, and concentrate was fed at 5.4 kg DM/cow per day. Pasture was allocated at 11.1 kg DM/cow per day. Milk yield was lower with PKE30 than PKE0 (14.3 versus 15.6 kg/cow per day, respectively). Feeding PKE20 and PKE30 was associated with a higher milk fat content of 50.6 and 52.9 g/kg, respectively, than that of 46.3 and 49.3 g/kg of cows fed PKE0 and PKE10, respectively. However, feeding PKE30 compromised fibre degradability. Increased milk fat content and sustained milk yield indicated that 200 g PKE/kg DM can partially replace maize in a dairy concentrate, resulting in a possible added economical advantage, which is dependent on the milk payment system. The lack of a significant effect on milk fat yield and the negative linear relationship of milk protein to milk fat ratio, induced by PKE inclusion, may be unfavourable for certain milk payment systems.
Keywords: By-product, fibre-based concentrate, Jersey cow, pasture, ruminal fermentation