Dairy Sheep Symposium - the Department of Animal Sciences ...

EFFECT OF REDUCING THE FREQUENCY OF MILKING ON MILK PRODUCTION,
MILK COMPOSITION, AND LACTATION LENGTH IN EAST FRIESIAN DAIRY
EWES
Brett C. McKusick 1 , David L. Thomas 1 , and Yves M. Berger 2
1 Department of Animal Sciences and 2 Spooner Agricultural Research Station,
University of Wisconsin-Madison
Madison, Wisconsin
Abstract
Efforts to improve milking efficiency of dairy ruminants have concentrated on improving
overall milk yield, or alternatively, on decreasing labor input yet still being able to obtain reasonable
milk yields. Because dairy ewes are capable of storing the majority of their total milk yield
within the cistern, longer intervals between milkings might be a reasonable management tool for
this dairy species. Forty-eight third parity East Friesian crossbred dairy ewes were randomly
allocated to two milking frequency treatments from d 90 to the end of lactation: 12H ewes were
machine milked twice daily at 0600 and 1800 (n = 24); 16H ewes were milked three times every
48 h at 0600, 2200, and 1400, respectively (n = 24). Milk production and composition were
measured every 15 d. For ewes managed with a 16 h milking interval, there was a 25% reduction
in the number of milkings compared to ewes milked twice daily (180 vs. 135 milkings,
respectively). However, there were no significant differences between 16H or 12H treatments in
milk yield (118 kg), milk fat percentage or yield (5.50% and 6.3 kg, respectively), milk protein
percentage or yield (4.78% and 5.5 kg, respectively), somatic cell count (4.67 log units), or
lactation length (178 d). We conclude that East Friesian dairy ewes are well suited for midlactation
management practices that include less frequent milking (up to 16 h). Longer milking
intervals reduces labor input and provides more time to producers for other on- or off-farm
activities.
Introduction
Efforts to improve milking efficiency in dairy ruminants have been focused on increasing the
amount of milk secreted, or conversely, by limiting the amount of labor required to remove milk
from the mammary gland (e.g. by reducing the number of daily milkings). Some dairy cow
farmers, for example in New Zealand and France, practice once-daily milking in early lactation
to reduce metabolic stress (Davis et al., 1999; Rémond et al., 1999), or in late lactation to accommodate
or improve quality of farming life (Davis et al., 1999). However, once-daily machine
milking, at least in dairy cows, results in significant losses in milk production on the order of 10
to 50% compared to twice daily milking (see review by Davis et al., 1999).
Physiologically, milking routines should be in accordance with intramammary filling rate and
cisternal capacity to store milk: overfilling of the udder results in increased intramammary
pressure, distention of the alveoli, and increases in amounts of feedback inhibitors of lactation,
all of which can compromise subsequent milk synthesis (Labussière, 1993; Peaker, 1980; Wilde
et al., 1995). Conversely, under-filling of the udder has been shown to reduce milk flow rate