Effects of predicted milk yields sustained by grazed grass on dairy cow performance and concentrate requirements throughout the grazing season |
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| Authors: | P J Purcell A J Dale A W Gordon J Barley C P Ferris |
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| Institution: | 1. Sustainable Agri‐Food Sciences Division, Agri‐Food and Biosciences Institute, Hillsborough, County Down, UK;2. Applied Plant Science and Biometrics Division, Agri‐Food and Biosciences Institute, Newforge Lane, Belfast, County Antrim, UK;3. Veterinary Sciences Division, Agri‐Food and Biosciences Institute, Belfast, County Antrim, UK |
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| Abstract: | The objective of this study was to examine the effects of predicted milk yields sustained by grazed grass (‘Milk‐from‐Grass’: LOW, MED or HIGH) and Parity (primiparous or multiparous) on the performance and concentrate requirements of grazed Holstein‐Friesian dairy cows offered concentrates on a ‘feed‐to‐yield’ basis during the grazing season. The mean Milk‐from‐Grass values assigned to cows in the LOW, MED and HIGH treatment groups (sixteen multiparous and eight primiparous cows per group) during the experiment (24 May to 2 October; 131 d) were 12·7, 15·4 and 18·1 kg cow?1 d?1, respectively. Concentrate allocations were adjusted every two weeks (approximately) based on individual cows’ milk yields, and concentrate was offered at a rate of 0·45 kg for each kg of milk produced above the assigned Milk‐from‐Grass value at that time. Increasing Milk‐from‐Grass from LOW to MED to HIGH decreased both the mean daily concentrate allocations (4·90, 3·17 and 1·79 kg cow?1 d?1, respectively) and milk yields (23·8, 21·8 and 19·0 kg cow?1 d?1) of the cows. Cows in the LOW treatment group had lower mean and final (i.e. at the end of the study) BCS and LW than those in the MED or HIGH groups. The effects of Milk‐from‐Grass were similar for both primiparous and multiparous cows. |
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| Keywords: | dairy cows grazing management concentrates body condition |
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