Milk Production of Fall-Calving Dairy Cows During Summer Grazing of Grass or Grass-Clover Pasture

Abstract

Milk production of fall-calving dairy cows during subsequent summer grazing was evaluated in two consecutive years using a total of 80 mid- to late-lactation Holsteins. Cows calved during September and October and grazed from April to August in the following year. In yr 1, 27 cows grazed a native grass pasture and 13 cows grazed a native grass-clover mixed pasture containing 26% red clover and white clover. In yr 2, 40 cows grazed native grass pasture as one group. Also, cows in yr 2 were administered bovine somatotropin, whereas in yr 1, no bST was used. Grazing cows also were fed concentrate supplements at 6.2 kg/d of dry matter (DM) in yr 1 and 7.9 kg/d of DM in yr 2 to provide 35 to 40% of total intake. Average daily milk during the grazing period decreased 3.6 kg in yr 1 and 7.7 kg in yr 2 when compared with milk yield extrapolated from the lactation curve established 10 wk before being turned out to pasture. Estimated DM intake during grazing was also less than what would have been expected had cows continued on a total mixed ration in confinement. Cows grazing the mixed pasture of grass and clover yielded 1.3 kg/d more milk than those grazing the grass pasture in yr 1. A decrease in milk resulting from the change from total mixed ration fed in confinement to grazing supplemented with concentrates was not avoided with these mid- to late-lactation cows, but the cumulative loss over the lactation was less than with early lactation cows in a companion study. Clover enhances the grazing value of pasture when grown with grasses.

The effect of feed regimen on chewing time, digesta passage rate and particle size distribution in Holstein non-lactating cows fed pasture ad libitum

“…While ingested pasture of Period 2 had high dietary NDF and low digestibility compared to pasture in Period 1, DMI of cow was not different between periods. This suggested that physical fill of the rumen may not have been a limiting factor for pasture intake, in agreement with Wu et al (2001). Eating time and bouts was significantly higher in treatment G than C (Table 2), in which may be reflected that the size of manger was not enough to offer to cows the sufficient amount of pasture during each eating bouts.…”

Grazing increases the concentration of CLA in dairy cow milk

“…These estimates suggest that the intake from the pasture was not sufficient to support a higher milk yield above the energy maintenance requirement that usually substantially increases because of grazing activities (NRC, 2001). Milk decreases are a common observation when cows are changed from a total mixed ration to grazing, often accompanied with BW losses, and the change is considered to result from insufficient intake from pasture because of small bite sizes (Wu et al, 2001). Mean ruminal pH, obtained from measurements taken during a 10-h period after feeding, was low for both treatments (5.84 and 5.94 for grazing and total mixed ration, respectively, P < 0.10; Table 3), reflecting the high starch content of the diets.…”

“…Grazed cows were also offered a supplement mix at 10 kg/day (dry matter basis) using ingredients similar to those included in the concentrate portion of the total mixed ration for the other group of cows. The allowance was used to provide 40% of the total feed intake, assuming that animals would obtain 60% of their intake from the pasture based on previous season estimates (Wu et al, 2001). The use of these values before the commencement of the experiment was necessary, but as reported below, the actual amount of the supplement consumed was less than offered.…”

Evaluation of alfalfa inter-seeding effect on bahiagrass baleage fermentation and lactating Holstein performance

“…Interseeding legumes into perennial grass pastures often increases animal growth and milk production above that of animals grazing pure grass stands [4,5]. Most of the research on interseeding legumes into grass pastures has been conducted in the Northeastern and Midwestern USA where conditions are favorable for legume production.…”