- Agronomic: sorghum (milo)
- Animal Production: feed/forage, housing, rangeland/pasture management
- Education and Training: extension
- Farm Business Management: feasibility study
- Soil Management: soil quality/health
The Regional Center for Sustainable Dairy Farming was initiated with Southern Region SARE funding in 1994. Objectives included a comprehensive comparison of two integrated systems of dairy production; one based on intensively managed pasture crops, the other based on row crops and conventional confinement housing and feeding. The comparison was organized to allow us to examine animal performance, health, seasonal reproduction, and non-point source water quality and soil conservation impacts of the two systems. Estimates of milk income, feed costs, labor, equipment, and investments were evaluated in the economic analysis. The project also included a strong outreach component which included demonstrations and dissemination of results to farmers, extension personnel, service industry personnel, students, and others.
The Dairy Educational Unit of NC State University’s Lake Wheeler Road Field Laboratory was the primary location of the experimental portion of the project. In addition, the teaching herd at NC A&T State University and cooperating producers in the region (VA, NC, SC) have been resources for various demonstrations, pasture walks, field days and as advisors.
The experimental project used groups of Jersey and Holstein cows assigned at calving to either the pasture-based system or to the confinement-feeding system. Cows were paired based on parity, age and milk production and then randomly assigned to the confinement or pasture group. When the project started in 1995, we used 24 Holstein cows and 12 Jersey cows in each replicate but since then we used 18 Holsteins and 18 Jerseys in each treatment group replicate. A replicate consisted a group of either 36 spring calving (January – March) or 36 fall calving (August – October) cows on pasture and a comparable group housed and fed in confinement. We have now completed the project, with a total of four spring-calving replicates and three fall-calving replicates. The economic analysis includes three spring and three fall-calving replicates.
Cows were kept in their respective groups through lactation but were managed together in other areas on the farm during dry periods. Healthy cows that rebred within the breeding season were kept in the same treatment group for the following lactation.
Cows in the confinement system were housed in a free-stall barn with access to an outside exercise lot. Rations included a blend of corn silage and alfalfa silage with various grains and by-product feeds fed as a total mixed ration. In contrast, cows in the pasture system were kept on pasture except for supplemental grain feeding and for milking. The pasture cows ration included ground corn, soybean meal, whole cottonseed, minerals and sometimes included cottonseed hulls. The pasture ration was fed in a covered feeding area before each milking. When pasture was limiting, higher levels of supplemental grain and by-products were fed in addition to hay or round-bale silage that had been harvested from the pasture system. The hay or round-bale silage was fed on pasture paddocks using a looped electric wire to keep the forage from being trampled and spoiled. During periods of extreme heat and humidity, pasture-based cows were allowed to stay in the shade of the covered feeding area for an extra hour or two after the mid-day milking.
The pasture area was approximately 74 acres which was divided into 37 two-acre paddocks with several combinations of cool season and warm season grasses and legumes. Most of the pastures were perennial species, supplemented with winter and summer annuals to allow for grazing throughout the year. Each paddock included a water source and was accessible from a 16′ travel lane.
Data collected included: daily milk yields, compositional analyzes of feeds and forages including fresh pasture, bimonthly pasture availability amounts, routine recording of udder infections (mastitis) and other health problems, weights and body condition scores of cows twice a month, reproductive information, and monthly concentrations of fat, protein, and somatic cell count in milk.
Multiple 24-hour cow watches were conducted for the pasture group to obtain an estimate of the distribution of feces and urine on pastures and the proportion of nutrients deposited in feeding and milking areas in contrast to pasture areas.
Results showed that some factors favored the confinement feeding system while others to favored the pasture-based system and some factors were similar for both. Milk production was higher for confinement-fed cows in all seasonal breed group daily averages except for one. Differences ranged from 2.6 pounds more milk per day from one group of pastured Holsteins to 13.3 pounds less milk per day for two other groups of grazing Holsteins. Jersey cows on pasture also milked less than those in confinement and Jerseys milked less than Holsteins across all lactation groups.
Measures of animal health and milk quality are also important in evaluating systems of production. Our work has documented that the overall incidence of udder infections (mastitis) was nearly twice as high for cows fed in confinement compared to cows on pasture (44% vs. 25%). Subclinical udder health can also be an issue but somatic cell count scores were similar for pasture and confinement cows. There were highly significant breed differences in incidence of mastitis with Holsteins at 41.2% vs. Jerseys at 25.8%. Culling and death losses for mastitis were also higher for confinement cows and for Holsteins. Other indications of animal well being include incidences of lameness, metabolic diseases, and death. Most disease and health problems were not notably different between the two groups. During the first year of the project, we had several Holstein cows in the pasture system with lameness due to sharp gravel in the travel lanes. The incidences of foot rot, displaced abomasums, and culling due to feet and leg problems were low and did not differ between the two treatment groups.
No differences due to treatment were observed although the overall pregnancy rate in a 75-day breeding period was numerically in favor of cows on pasture (71.7% vs. 64.2%). However, there were obvious 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 is a function of the other measures and was 78% for Jerseys compared to only 57.8% for Holsteins.
Body weight changes and body condition scores have shown that cows in the pasture system do not carry as much weight and condition through the lactation. This may have been due to the increased exercise from walking to and from pastures and during grazing.
An important issue in comparing the two systems was the deposition, collection, and recycling of nutrients. All of the feces and urine of the confinement cows had to be handled or processed in some way whether from the feeding, housing, and milking areas or from the bare exercise lot. This required special needs for handling, storage, and redistribution of nutrients to cropland or other uses. In contrast, our 24-hour cow watches have shown that 87% of urine events and 86% of manure events occur in or near paddocks where the nutrients are available for pasture use. This means that a pasture-based system has to design storage and handling facilities for only about 14% of manure plus milking facility wash water. In addition, water pollutant runoff data showed that runoff from the confinement drylot area contained more than 19 times the amount of sediment than runoff from the pasture area when adjusted for cow use. Similarly, total nitrogen and total phosphorus runoff levels for the drylot area were more than 12 times the amounts from the pasture area.
In the economic analysis, milk production and income over feed costs generally favored the confinement cows but adjustments for mastitis and culling for mastitis reduced that advantage measurably. Differences in labor were small but in favor of pastured cows, particularly when manure handling is considered. Investments in equipment to support cropping practices and manure management would also be less for pastured cows under most scenarios. Housing and feeding system investments can also be lower for pastured cows. In reality there is a wide variation in profitability of dairy farms and such variability is likely to be evident among pasture-based dairies as well. Under our milk and feed price structure, a computer simulation indicated that the potentially most profitable pasture system would include high stocking rates and substantial supplementation. Documented financial records do indicate that pasture-based dairy farms can be profitable.
A short-term milk sample study was performed using the Spring1998 calving group during the summer of 1998. Milk samples were obtained from each cow for four consecutive weeks and analyzed for fatty acid composition, including the fatty acid conjugated linoleic acid (CLA) which has been identified as a natural anticarcinogen. The pasture cows had a significantly higher concentration of CLA in their milk compared to the confinement cows and Holsteins had higher concentrations of CLA than Jerseys.
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 much 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 are still less than optimal.
These results should help define alternative dairy production systems for the southeast. A farm-scale pasture-based system was dedicated in 1998 in eastern North Carolina to further examine the potential of pasture-based systems in the region. Because the region is milk deficient for much of the year, this project should lead to a more competitive local supply of milk at reasonable prices for consumers. In addition, successful 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.
The project investigators have been quite active in outreach efforts with participation in 6 field days (two hosted), two grazing schools for dairy producers and four for NRCS employees, and poster exhibits at three regional and one national sustainable agricultural conferences and at other conferences. Papers have been presented at several meetings and this project has served as a focal point for several formal and informal tours. With subsequent funding from the SARE Professional Development Program, the project investigators also initiated a dairy farm study tour of Ireland and Northern Ireland, from which multidisciplinary training sessions were developed and presented, including much of the data from this project. At least twenty dairy producers in the region have greatly increased use of pasture in their management systems including a few new dairy farms organized as pasture-based herds from the start. Discussion support groups are becoming more active among dairy graziers in the region. Currently, two new (one small and another large) pasture-based dairy herds are being planned in the region.
a. Compare and evaluate profitability of two integrated systems of dairy production; one based on intensively managed pasture crops, the other based on row crops and conventional confinement housing and feeding.
b. Evaluate the impact of the pasture-based system on animal performance and health compared to the conventional confinement system.
c. Examine the feasibility of seasonal milk production within pasture-based and conventional confinement systems.
d. Evaluate non-point source water quality and soil conservation impacts of land uses under the pasture-based and row crop forage systems.
e. Demonstrate and disseminate the results among farmers, extension personnel, service industry personnel, students, and others.