The effect of replacing maize with dried apple pomace in the concentrate on performance of Jersey cows grazing kikuyu pasture

Dried apple pulp (DAP) is a by-product of the apple juice industry. It has a comparable ME and CP content to maize but has a higher NDF content. It has been used as a substitute to maize with success in various TMR systems, offering an affordable alternative to maize. The aim of the study was to determine whether the replacement of maize with DAP would be beneficial to milk production and rumen health of Jersey cows grazing kikuyu pasture. Seventy two lactating Jersey cows were blocked according to milk yield, days in milk and lactation number. Cows within blocks were randomly allocated to one of four treatments. Treatments were: 0% DAP inclusion (AP 0), 25% DAP inclusion (AP 25), 50% DAP inclusion (AP 50) and 75% DAP inclusion (AP 75). Cows received 6 kg as is/day of the allocated concentrate in the milking parlour. Cows of all four treatments strip grazed kikuyu-ryegrass pasture, as one group, over an area of 8.6 ha. A rising plate meter was used to estimate pasture DM yield pre- and post-grazing and manage the allocation of pasture. Pasture samples and feed samples were collected on a weekly basis, dried at 60° C for 72 h and pooled every two weeks. An additional eight ruminally cannulated cows were used and were subjected to a four period crossover design with a 14 day adaptation period between treatments. Rumen pH, pasture DM and NDF degradability and VFA profile were determined. Treatment did not have an effect on milk yield; however, there was a linear decrease in 4% FCM and fat yield as the level of DAP inclusion in the diet increased. Cows receiving the AP 0 concentrate supplement yielded 0.9 and 1.2 kg more 4% FCM than cows on the AP 50 and AP 75 concentrate supplements (P < 0.001), respectively. Treatment had no effect on milk composition, except for the lactose content which was lower for cows receiving the AP 0 concentrate supplement (P < 0.001). Average rumen pH was lower for cows receiving the AP 75 concentrate supplement (P < 0.001); however, treatment did not affect the VFA profile or pasture DM and NDF degradability. It was concluded that the replacement of maize with DAP for cows grazing kikuyu pasture is a viable option; however, the possible decrease in 4% FCM yield should be taken into consideration.