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Research data were collected on two different dairying systems: (1) the pasture-based system in Puerto Rico versus (2) the confinement plus forage and concentrate feeding system largely followed in Florida. The dairy industry is an integral part of Florida agriculture and the state’s economy. There are about 178,000 dairy cows in Florida, and revenue from milk sales exceeds $385 million per year. In Puerto Rico, cow numbers total about 88,000 and milk sales contribute $185 million annually to the island’s economy. Florida dairy herds are large, averaging 600 cows per farm. Most lactating dairy cows in Florida are housed in confinement and fed diets containing mixtures of forage and concentrates. In contrast, the Puerto Rico industry is pasture-based, with cows receiving concentrate supplements.

In the past two years, some Florida dairy farmers have begun to adopt pasture-based production systems. Reasons for this change include high capital inputs for buildings and equipment on total confinement dairies, increasingly negative public perception of the effects of dairies on quality of life of surrounding communities, and growing pressure by regulatory agencies and environmental interests.

Over 90% of the 475 dairies operating in Puerto Rico at the end of 1993 depended partially or totally on grazed pastures to supply forage to lactating cows. Grazed pastures occupied over 92% of the total cultivated land area on these farms. In the past, stocking rates on dairy pastures were low, however, recent urban development spawned by rising land value has resulted in smaller farms and greater stocking rates. In the Arecibo milkshed, where 60% of the cows are concentrated, stocking rate is about 3.7 cows per hectare. Greater animal pressure on available grasslands requires better pasture management to maximize forage yield, optimize nutritive value, and maintain farm profitability.

Research was needed to address the void of information on pasture-based dairying in Florida. Questions addressed included: effects of forage species grazed, stocking rates imposed, and amounts of concentrate fed on (a) milk production and farm profits, (b) nutrient cycling and commercial fertilizer requirements of the pasture, and (c) water quality. One objective was to assess milk income over feed costs for different pasture management and grain feeding systems. Two pasture types were grazed at two stocking rates and lactating cows grazing these pastures received two different rates of grain supplement.

Impact

Income over feed costs varied by more than $0.60 per cow per day for the treatments tested. Thus, for an average Florida dairy farmer housing 600 cows, choosing the best treatment could result in an increase in income of $360 per day. Highest income over feed costs was achieved using rhizoma peanut as the forage with a stocking rate of 5 cows per hectare and when cows were receiving about 5 kg of grain supplement per day.