S-A. TURNER, C.V.C. PHYN, E.S. KOLVER, P.W. ASPIN and N. LOPEZ-VILLALOBOS
Proceedings of the New Zealand Society of Animal Production 68: 79-83
Dairy product mix and milk value were investigated in Holstein-Friesian cows of New Zealand or overseas origin that grazed pasture and were supplemented with 0, 3 or 6 kg DM concentrate/cow/day during a 600-day extended lactation. A dairy product supply chain model was used to predict relative changes in dairy product mix and milk value during the "extended period" (300 to 600 days in milk) compared with the "normal period" (0 to 300 days in milk). Cow genotype and level of concentrate supplement affected dairy product yields, with little consistency of effect between "normal" and "extended" periods. Milk produced during the "extended period" resulted in more cheese, butter, butter milk powder, casein, and whey protein concentrate, but less whole milk powder, skim milk powder and whey milk powder compared to the "normal period". The overseas strain and those cows receiving higher levels of concentrates had less of a decline in whole milk powder yields associated with the "extended period". Milk value ($/L), was predicted to be 20.8% higher during the "extended period" compared with the "normal period". These results indicate that extended lactations may improve the dairy product mix and milk value following processing.
Keywords: NZSAPAB; extended lactation; dairy product mix; milk value; genotype; concentrate supplementation
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