Regional Center for Sustainable Dairy Farming
The Regional Center for Sustainable Dairy Farming included a comprehensive comparison of two systems of dairy production; one based on intensively managed pasture, the other based on row crops and conventional confinement housing and feeding. We examined animal performance, health, seasonal reproduction, environmental, and economic impacts of the two systems. Outreach included dissemination of results to farmers, extension personnel, service industry personnel, students, and others as the project progressed.
NC State University’s Lake Wheeler Road Field Laboratory was the location of the experimental portion. The teaching herd at NC A&T State University and cooperating producers in the region (VA, NC, SC) were resources for various demonstrations, pasture walks, field days and participated as advisors.
The project was based on use of groups of Jersey and Holstein cows assigned at calving to two feeding systems. At the start, we used 24 Holstein cows and 12 Jersey cows but later there were 18 Holsteins and 18 Jerseys in each treatment group replicate. A replicate consisted of either 36 spring calving (Jan. – Mar.) or 36 fall calving (Aug. – Oct.) cows on pasture and a similar group in confinement. Data collected include 4 spring-calving replicates and 3 fall-calving replicates. Cows were kept in respective systems through lactation but were grouped together elsewhere during non-lactating periods. Healthy cows that conceived were kept in the same treatment group for their next lactation.
The confinement system was a free-stall barn with an outside bare exercise lot. Rations included a blend of corn silage and/or haylage with various grains and by-product feeds and fed as a total mixed ration. Cows in the pasture system were kept on pasture except for supplemental grain feeding and for milking. When pasture was limiting, additional supplemental grain and by-products were fed and/or hay or hay-crop silage was offered.
The pasture was 37 approximately two-acre paddocks with combinations of perennial cool season and warm season grasses and legumes to allow for grazing throughout the year. Winter and summer annuals were used strategically. Each paddock was accessible from a 16′ travel lane and included water.
Data included daily milk yields, weekly estimates of feed intakes, analyses of feeds and forages including fresh pasture, routine recording of udder infections (mastitis) and other health problems, weights and body condition scores of cows, reproductive information, and monthly concentrations of fat, protein, and somatic cells (udder health) in milk. Storm water runoff samples were collected from a 3-acre exercise lot and from drainage from about 22 acres of pasture area for nutrient and sediment analyses. Cow watches were conducted to estimate distribution of manure on pastures and the proportion of nutrients deposited in feeding and milking areas in contrast to pasture areas.
Milk production was higher (P< .05) for confinement-fed cows and seasonal averages differed by 9 to 16 % between subgroups. This meant reduced milk income for cows in the pasture system. Feed costs were lower for cows using pasture but that alone did not offset the difference in income. Jersey cows milked less than Holsteins and milk income over feed costs was also lower for Jerseys in both systems. Based on data from the project and a computer simulation model, one PhD dissertation examined differing stocking rates and supplementation strategies on pasture systems and projected that moderate to high stocking rates and high concentrate supplementation would improve the profitability of the pasture system. That projection did not consider potential effects on animal health or manure nutrient management.
Incidence of udder infections (mastitis) was higher for cows in confinement versus cows on pasture (42.2% vs. 22.8%, P< .05). There were also significant (P< .05) breed differences in incidence of mastitis with Holsteins at 41.1% vs. Jerseys at 23.9%. Adjustments for udder health and milk loss reduce differences in net production income for Holsteins over Jerseys and for the confinement system over grazing.
No differences due to treatment were observed in reproductive measures, but the pregnancy rate in a 75-day breeding period was numerically higher for cows on pasture. There were breeding efficiency advantages for Jersey cows over Holsteins in first service conception rate, conception to all services, proportion of cows inseminated and overall pregnancy rate. Overall 75-day pregnancy rate was 84.2% for Jerseys compared to only 58.9% for Holsteins (P< .05).
Body weight changes and body condition scores have shown that cows in the pasture system were thinner (.2 to .6 points on a 5-point scale; P <.05) through the lactation.
All of the feces and urine of the confinement cows had to be handled or processed in some way. This requires special needs for handling, storage, and redistribution of nutrients to crop land or other uses. In contrast, 24-hour cow watches showed that 87% of urine events and 86% of feces events occur in or near paddocks where nutrients are recycled for pasture use. Therefore, a pasture-based system only needs storage and handling facilities for about 14% of manure plus milking facility wash water.
Nutrient runoff from the bare exercise lot had high concentrations of sediment and nutrients. Measures of carbon-oxygen demand and conductivity were also high for storm water runoff from that lot used by confinement cows (and other cows not on experiment). In contrast, such measures were significantly lower for runoff samples from pasture. The densely vegetated, rotationally grazed pasture was effectively retaining feces, urine, and soil on the field instead of washing away during storm events. Additional structures have been installed for runoff from the bare exercise lot to prevent nutrients and sediment from reaching the stream. Because of the runoff data, confinement cows are to be managed in the future using rotational vegetative lots for exercise.
In our environment, the pasture-based cows have lower housing and facility requirements and perhaps lower equipment needs. Both confinement and pasture systems have equipment needs that may vary depending on the size and scale of the farm. Estimates of labor requirements were lower for the pasture system but can vary from farm to farm. These factors must be considered in any economic analysis or for dairy producers considering alternative approaches.
Observations from the teaching herd at NCA&T State University have shown an estimated reduction in feed costs by at least 25% from 1995 before the grazing management program was initiated. They also report 50-60 % less time scraping and handling manure because cows are on the pasture much more of the time. Body condition of cows has remained acceptable and overall health problems have been low. However, milk production and reproduction in the herd were less than optimal and alfalfa-based pastures deteriorated over time.
When all factors are considered, pasture-based systems appear to be economically feasible for some producers as an alternative dairy production system for the Southeast. Pasture-based dairy systems can enhance local communities in several ways including economic stability, green space, and a pleasant rural environment compatible with nearby residential areas.
Outreach efforts include several field days and grazing schools for dairy producers, extension agents, and NRCS employees. Poster presentations have been at several events and a paper was presented at Tufts University in 1995. This project has been a focal point for several tours and some dairy producers have increased use of pasture in their management systems. December 1998.