Well Managed Pastures = Superior Heifer Gains

Dr. Ronald L. Boman
USU Extension Dairy Nutritionist

At the Utah State University 'George B. Caine Research & Teaching Center' for the past two years bred Holstein dairy heifers have gained 1.75 (1998) and 2.0 (1999) lbs/day for the grazing season on perennial ryegrass/white clover pastures. These heifers have grazed one or two days after the milking cows have had first chance to graze the same pastures. The only supplement offered to the heifers was a free choice salt/mineral mix with Bovatec. Even though the heifers grazed after the milking cows, there was still an adequate amount of grass available for them.

With these two years of data I was convinced that bred heifers (950 to 1050 lbs) would make satisfactory gains under this type of management. What I didn't know was if yearling heifers could be expected to gain well enough grazing after the milking cows. The weight gain of 24 yearling Holstein heifers for the first 29 days of this year's grazing season are presented in Table 1. These heifers grazed one or two days behind the milking cows and had free choice access to a salt/mineral mix with Bovatec as the only supplement. Of course, clean drinking water was available at all times and there was ample pasture available. These heifers had slick hair coats and looked really athletic. We were surprised to find when we weighed them that they had gained 2.71 lbs/day.

Table 1. Middle grazing yearling heifers, 2000.

Initial Weight 652.9 lbs May 4 & 5
29-day Weight 731.4 lbs June 2
ADG 2.71 lbs 24 Heifers

These heifers grazed paddocks after the lactating cows had grazed.

The bred Holstein heifers were the clean-up grazers. They grazed after the yearling heifers. Here again there was ample pasture available, even though they were forced to clean up after the other two groups. As shown in Table 2, the average daily weight gain for 23 bred heifers was 2.87 lbs. These gains are remarkable considering that they were the third grazers. Heifers were offered a new pasture every 48 hours and we tried to leave at least a 2 to 3 inch residual of the grass after all groups had grazed so that there was enough leaf surface for photosynthesis and regrowth to occur.

Table 2. Last grazing bred Holstein heifers, 2000.

Initial Weight 1125.5 lbs May 4 & 5
32-day Weight 1217.3 lbs June 5
ADG 2.87 lbs 23 Heifers

These heifers grazed paddocks after cows and after yearling heifers.

We will be weighing these heifers every four weeks during the grazing season. We may not get quite as good gains for the rest of the season, but I expect that both groups will average over 2 lbs of daily gain. Why do I say that?

Because "Management Intensive Rotational Grazing" implies that:

� Grasses and legumes will be maintained in a vegetative stage of growth, preferably no more than 6 to 8 inches tall.

� We will provide irrigation water to keep the grass growing. This may mean sprinkling every 7 to 10 days (for about 12 hours each set) during the heat of the summer. Flood irrigation, if used, should probably occur every 10 to 14 days during this hot period.

� Grasses really respond to nitrogen fertilization (assuming that the other fertilizer nutrients are available in proper amounts). We have applied up to 200 units of nitrogen during the pasture season. We have found it convenient (and effective) to add nitrogen fertilizer in small amounts through the irrigation system each time we sprinkle.

� We will provide adequate drinking water in the paddocks for the grazing cattle. They will never run short of water!!

� We will control flies and internal parasites and frequently monitor animals for injury or sickness and treat them promptly.

Management Intensive Rotational Grazing is not a "Silver Bullet" that will solve all of your problems. It does require attention to details and a commitment to succeed, but it will pay big dividends if done properly.