Integrating tropical legumes with condensed tannins into ruminant grass-based diets for sustainable production
In Puerto Rico, urban spawn has forced beef producers to diversify (increased sheep and goats farms) and move pastures to less productive marginal lands. Ruminant production are crucial to the economies of both islands and are reliant on tropical grasses, though abundant in the wet season, are of low quality and cannot meet the nutritional requirements of growing ruminants. Concentrates typically used to bridge this nutrient requirement gap are imported at considerable costs ($20 per 50lb of concentrate feed) are not economically viable. In the emerging small ruminant industry (Mutton and Chevon sells for $4-5 lb in Puerto Rico), producers are now faced with parasitism of gastrointestinal nematodes (GIN) resulting in marked production losses pre- and post weaning, in addition to the developed resistance to anthelmintic drugs by GIN. Creep grazed or conserved tropical legumes containing condensed tannins (CT) to provide supplementary nutrients may reduce parasite loads and will likely enhance growth rates and increase profitability, but these hypotheses needs to be verified in on farm research trials.
Research objectives were: (i). Determine intake, digestibility and nitrogen balance of lambs fed diets of tropical grass hay (eg. blue stem; Dicanthium annulatum or guineagrass; Panicum maximun Jacq.) supplemented with tropical legumes with condensed tannin (CT) [perennial peanut (Arachis spp.); desmodium (Desmodium heterocarpum (L.) DC. Subsp. ovalifolium (Prain.) cv. Maquenque, calliandra (Calliandra calothyrus)] and pigeonpea (Cajanus cajan), (ii). Determine average daily gain and parasite load of lamb-crops creep grazing CT tropical legumes (perennial peanut, demodium, calliandra and pigeon pea), (iii) On-farm demonstrations of CT legumes and their effects on parasite control on small ruminants, and (iv). Prepare economic costs and returns of forage and small ruminant production on conventional dewormers vs. dewormer banks.
University of Puerto Rico: Elide Valencia, Professor of Agronomy, University of Puerto Rico, Mayaguez
Studies were conducted at the University of Puerto Rico, Agricultural Experiment Sub-Station of Corozal during the period between April-November, 2009. St. Croix White hair sheep growing lambs [n=5; 15 kg body weight (BW)] and replicated twice were used for this study. There were two treatments; treatment 1 consisted of daily and night rotational grazing of an already established guineagrass (Panicum maximum Jacq.) – perennial peanut (PP; Arachis pintio) stand during the period between 1:00 PM to 7:00 AM and supplemented with guineagrass hay (3% BW) during the day, while treatment 2 consisted of rotational grazing of pure guineagrass stands during the same period. Mineral salt block was offered ad lib during the morning. Weekly, lambs were offered 200 g/animal of the condensed tannin (CT) containing Calliandra calothyrsus shrub and weight taken. FAMACHA to assess anemia was done biweekly and lambs with a score above 3 were treated with a dewormer. There were differences on average daily gain (ADG). Lambs on the legume association gained 62 g/d compared to 30 g/d on grass alone (a two-fold increase in ADG). Lambs on guineagrass-PP required less deworming (2 xs during the period of the study compared to 5x those on grass alone). The CT legume appeared to have minimum effects when offered on the low quality guineagrass. This study will be repeated in 2010.
Metabolic cages have been built to assess intake, digestibility and N balance of CT legumes and low quality grasses in the summer of 2010.
The study was conducted at farmer cooperator Vicente Ortíz, Barceloneta, Puerto Rico during the period between May to December 2010. The objective of the present study was to assess live weight performance of pre- and post weanling milk Nubian goats creep grazing CT Calliandra calothyrsus and followed by evaluating two contrasting diets using dried and ground Morus alba (MA) produced in situ within the farm compared to goat concentrate feed. Twelve kids (2-wks old) of Nubian milk goats creep grazed perennial peanut and CT Caliandra for 3-mo. There were no differences on weaning weight (17.5 kg BW). However, this weaning weight surpasses the traditional weaning on non-creep grazed legumes by 5 kg. At post weaning, kids (N=3) were randomly assigned to a semi-confinement feeding systems of a free choice offer of bluestem grass hay supplemented with ground MA (harvested at 3-mo regrowth and sun-dried for 5d) at 3% BW and a free choice offer of bluestem hay plus a goat concentrate (600 g/kid for the first 3 mo and 800 g/kid for the additional 3 mo.), a management practice used by the farmer for developing young goats. Animals allowed pasturing 5 h daily. Kids were weighed weekly. There were no differences between feeding systems. Average daily gains on supplemented MA were 58 g/d compared to 62 g/d on those fed with concentrates. Breeding stock was marketed at 9-mo age.
Farmer Cooperators: Guillermo Martinez, Altamira Norte, Vega Baja
Between July-December 2009, a protein bank of Morus alba (MA) and a deworming bank of CT Calliandra were established. Four hundred seedlings of MA and CT Calliandra were planted in a 0.20-area. At 4-mo post-planting, 17 adult lambs grazed both banks, and shrub plants were cut at 15-cm height to induce tillering. In addition, a 0.20-ha area of guineagrass and PP association was also established. Sheep flock was bred to lamb in the fall of 2010. Following the lambing period, a creep grazing study using MB, CT Calliandra and the association will be conducted and will be followed by a post-weaning average daily gain study.
Agriculture Economist, Gerard D’Souza has developed surveys and training workshops have been planned for August 2010 with farmer cooperators.
University of the Virgin Islands, Agriculture Experiment Station, St. Croix USVI: Prof. Stuart Weiss.
CT Calliandra calothyrsus has been successfully established and studies to test antihelmintic effects will be conducted in 2010.
Impacts and Contributions/Outcomes
In addition to three farmer cooperators participating on the on-farm research, 10 other small ruminant farmers have benefited from the use of MA and CT Calliandra. The local Department of Agriculture, Puerto Rico provided additional funds to our program to prepare seedlings to be distributed to other small ruminant famers. In the fall, a field day was conducted at Guillermo Martinez farm to discuss the establishment and use of CT legumes and to be repeated in May 2010. Twenty-five farmers participated in the first field day.
Agricultural & Resource Economics Program
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