Sustainable Year-Round Forage System for Goat Production in the Southern USA
Preliminary defoliation pattern, stocking rate and weight gain data were obtained using 45 goats rotationally stocked on the mimosa paddocks for 49 days. The mimosa defoliation pattern was monitored for 14 days. Partial defoliation is unlikely to result in higher forage production than complete defoliation. Animals gained 55.7 to 175.7 g/day, and ADG was 102.6 g/day. Animals with an initial body weight of 15-20 kg gained more than those with lower or higher BW. Also, four acres were seeded with Marshall annual ryegrass and are currently being grazed by 26 goats to obtain data on stocking rate and weight gain.
- Study the pattern of foliage removal from mimosa by goats, and determine the optimal degree and frequency of defoliation.
Establish the optimal stocking rates and associated animal weight gain for goats when feeding on mimosa in summer, and annual ryegrass in winter.
Determine whether mimosa has any anthelmintic effect when browsed by goats.
Determine carcass quality and if there is a consumer preference for meat from browse-fed goats.
Compare productivity of goats on ryegrass with that of cattle.
Evaluate (on an experiment station) and demonstrate (on two small farms) an integrated year-round forage system of mimosa in summer and annual ryegrass in winter for goat production by limited resource farmers.
Defoliation pattern of mimosa plants was studied using 45 goats placed on one acre of mimosa field for 14 days. Mimosa plants were marked prior to introduction of the animals. Foliage removal by animals was observed daily. Unlike cattle and deer, goats strongly selected the leaflets from mimosa leaves, and did not consume the rachis unless the leaf was very young. Previous observations indicated that cattle consumed the entire leaf, as well as twigs up to 0.25 in. in diameter. Deer tend to remove the entire distal portion of the leaf, including both rachis and leaflets, but leave the entire basal part of the leaf intact. However, goats tended to remove all the leaflets from a leaf, leaving the entire rachis intact. This suggests that goats are more selective than deer (for details, see attached paper). In addition, goats tended to completely (not partially) defoliate one stem at a time. Therefore, partial defoliation of all the plants in a paddock is really not feasible, and will not lead to higher forage production than complete defoliation (as has been observed in previous hand defoliation studies). These preliminary results were definitely not predicted and are therefore extremely useful. Altering canopy structure by pruning stems to about 2 ft and allowing only limited re-growth prior to defoliation may be more effective in achieving more uniform partial de-foliation. Therefore, this is the approach that will be applied in 2003.
Mimosa Study: In July and August, 2002, five acres of mimosa were fenced with goat- and predator-proof (mesh and electric) fencing into five one-acre subdivisions for rotational stocking, with shelters and facilities to pen animals at night. Major annual weed infestations of the mimosa paddocks were also eliminated by hand on these five acres during this same period. Forty-five animals with average initial BW of 16.6+3.98 kg were placed on about 5 acres of mimosa plant fields for 49 days. The paddocks were mown in April 2002, and growth was allowed to accumulate without defoliation for the entire summer. By the end of August, mimosa plants had mostly 5 to 8 stems that ranged between 6 and 10 ft in length. Animals were allowed to browse during the day and they were penned at night to protect from predators. Body weight was recorded every two weeks. Preliminary results indicated that body weight gain ranged from 55.7 g/day to 175.7 g/day with ADG of 102.6+ 27.4 g. Animals (n=19) with initial body weight (IBW) of 15-20 kg performed better (ADG=114.9+5.9, P<0.03) than those (n=19) with lower (10-15 kg, ADG=92.0+5.9 g) or (n=6) higher IBW (20-29 kg, ADG=97.2+10.5 g). Smaller animals were probably more challenged to reach the higher branches (6-10 ft) and older animals had slower growth rate. Mimosa plants should be pruned at a lower height (2 ft.) or, for best performance, goats should reach certain weight (IBW of at least 15-20 kg), before placing on mimosa. In December 2002, and January 2003 all mimosa plants in all 5 one-acre paddocks were pruned by hand to a height of about 2 feet in preparation for the 2003 experiment. Preliminary results are very promising when compared to reported ADG of 131 g for similar size goats (IBW of 21 kg) kept indoors and consuming more than 80% grain in their diet (Hopkins and Solaiman, 2002).
Ryegrass Study: In September 2002, 4 acres were plowed and seeded with Marshall annual ryegrass for grazing with goats, in addition to 72 acres for the beef cattle grazing experiment. The goat pasture was again fenced into two 2-acre subdivisions with goat- and predator-proof fencing. Twenty-six goats have been placed on one of the two 2.3 acres of ryegrass pastures. Animals will be rotated between the two pastures as needed. Body weights are recorded every two weeks. Forage samples are collected monthly for forage quality determination. Effect of animal on soil characteristic and compaction will be tested before and after the introduction of animals. At the end of the grazing study, 8-10 animals will be harvested to determine carcass characteristics and composition. The rest of the animals will be marketed according to a marketing plan. Sale barns in 50, 100, 150 and 200 miles radius will be strategically located to sell the animals for maximum profit.
Four animals were selected for this preliminary study to evaluate strategic de-worming method in goats and establish optimum level of parasite load for mimosa study. Animals were strategically de-wormed with cydectin (1cc/ 25 lbs. BW) for three weeks and feces were collected for fecal egg counts. Parasite free animals were inoculated with 100, 500 and 1000 eggs (Haemonchus contortus). Fecal samples were collected and monitored for several months. Animals remained clear of parasites for rest of the experiment indicating that re-inoculation was not sufficient for establishing a parasite load and reconfirming the fact that if de-worming is conducted strategically and the environment is kept clean, animals can remain clear of parasites even after re-inoculation. These animals have been placed on pasture and will be monitored for possible recontamination.
At the end of the ryegrass grazing study (under objective 2), 8-10 animals will be harvested and preliminary data on carcass characteristics and quality will be determined. Baseline data on consumer preference for meat from grazing goats will be established so it can be compared with the data collected from browsing or grain fed animals.
In September 2002, 4 acres were plowed and seeded with Marshall annual ryegrass for grazing with goats, in addition to 72 acres for the beef cattle grazing experiment. Preliminary data collected on goats’ performance and productivity will be compared with that of cattle collected in the similar conditions.
Preliminary contacts have been made and two independent producers have been identified. We will work with these producers and their farms will be used as demonstration sites. As more information is collected, on goats grazing on ryegrass and browsing on mimosa, they will be communicated with the producers and demonstration farms will be developed.
We would like to use purebred Boer goats as well as crossbred animals for this project. We will collect data from animals placed on mimosa, a warm season grass, as well as grain fed goats, to compare animal performance and carcass characteristics of browse, grass and grain fed goats. Stocking rates will be determined. A set of animals will be strategically de-wormed and re-inoculated, half will browse on mimosa and half will be fed indoors to test its anthelmintic activities and if in fact mimosa can reduce the burden of GI parasites.
One of the major problems encountered is finding uniform research goats. The goat market is not developed in Alabama and it is very unstable and unpredictable. Finding more than 10 uniform goats for research can be a great challenge. Grazing studies require more than 30 goats at one time.
Bransby, D. I., S. G. Solaiman, C. R. Kerth, R. Noble, S. Sladden and S. Durbin. 2003. Defoliation patterns of goats browsing mimosa. Proceeding, AFGC. Submitted
Hopkins, C. E. and S. G. Solaiman. 2002. Effect of high dietary copper on performance and carcass characteristics in goats. J. Ani. Sci.(Suppl. 1). Abstract.
Impacts and Contributions/Outcomes
A combination of mimosa in the summer and Marshall ryegrass in the winter is likely to provide an outstanding year-round forage system for goat production by limited resource farmers in the southern US. However, no data is available to develop the best management practices for this system, and to clearly demonstrate its superiority over typical systems currently being used (based primarily on perennial grasses). In order to establish optimal management practices, it is necessary to know how animals defoliate forage plants. Altering canopy structure by pruning stems to about 2 ft and allowing only limited re-growth prior to defoliation may be more effective in achieving more uniform partial de-foliation. This research will help establish some guidelines for the most profitable and efficient grazing/browsing practices for goats. Besides providing a high quality diet, browsing in summer may also reduce the infestation of GI parasites (major problem in Southeast), when goats spend less time grazing close to the ground where the larvae of these pathogens are present in large quantities.
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