Dairy Production From Pasture; A Comparison of Two Methods of Controlled Grazing at Two Rates of Stocking

Abstract

An experiment was started in 1957 that compared the production from dairy cows on daily stripfolding with that from a system of rotational grazing where the cows were given a fresh allocation of pasture about once or twice a week. Management was so arranged that equal areas of pasture were grazed off by the same number of cows in a similar period of time. The experiment was carried out at two rates of stocking, one about 20% greater than the other, the lower rate considered to be equivalent to good close folding practice and the higher rate therefore somewhat restrictive. No supplementary food was given during the grazing season.At the high rate of stocking, rotational grazing gave an average milk yield of 40 lb./cow/day whilst daily strip-folding yielded 38 lb./cow/day. At the low rate of stocking production was 42 Ib./ cow/day for both methods.At the high rate milk yield/acre from the rotational grazing was 1007 and from the strip-folding 977 gals. At the low rate comparable results were 881 and 874 gals.There was no general trend in yield per cow or per acre in favour of either the rotational grazing or daily strip-folding systems of management. Increasing cow days/acre by 21% decreased yield/ cow/day by 7% but significantly increased milk yield/acre, by 13%.

Effect of Stocking Rate on Pasture Production, Milk Production, and Reproduction of Dairy Cows in Pasture-Based Systems

“…This is consistent with the positive association between milk production per hectare and SR in many studies (Gordon, 1973;Baker and Leaver, 1986;Dillon et al, 1995). However, many of these experiments were short term (Castle et al, 1968;Gordon, 1973;Baker and Leaver, 1986;Kennedy et al, 2006), compared insufficient SR treatments (<3) to determine an optimum SR (Foot and Line, 1960;Castle et al, 1968;Gordon, 1973;Dillon et al, 1995), or included the use of purchased supplementary feeds (Fales et al, 1995), in effect modifying the true effect of SR on the biological (pasture utilization, milk production/cow, milk production/ha) and economic variables measured. Furthermore, much of this research is more than 30 yr old and may no longer be applicable to the modern dairy cow breed and strains being used globally.…”

“…Previous research investigating the effect of SR in grazing systems on milk production per cow and per hectare did not allow us to predict the effect of SR change. The research in question was either short-term and unable to account for the complete farm system (Castle et al, 1968;Baker and Leaver, 1986;Kennedy et al, 2006), was undertaken more than 30 yr ago (McMeekan, 1956;Foot and Line, 1960;Castle et al, 1968;Gordon, 1973), and considering the advances in cow genetics and farm management over that time, may no longer be applicable; or they merely compared "high" vs. "low" SR treatments, making it impossible to determine an optimum SR for any production system or to extend their results beyond the system investigated (Foot and Line, 1960;Castle et al, 1968;Gordon, 1973;Dillon et al, 1995).…”