Recipient Organization
VIRGINIA STATE UNIVERSITY
(N/A)
PETERSBURG,VA 23803
Performing Department
(N/A)
Non Technical Summary
The United States (US) is experiencing a growing demand for live and processed meat goats and sheep that mirrors demographic diversity along the East coast with increases in ethnic populations. These demographic changes were partly responsible for over 250,000 increases of frozen imports through the Philadelphia port between years 2000 and 2008 and up to 100,000 through other US ports. The growing US market demand for meat goats also mirrors increasing consumer preferences for tastier, more nutritious, and healthier organic farm products such as grass-fed meat/ milk, even at higher premiums. The growing demand for meat goats presents alternative income opportunities for limited-resource producers, who cannot afford more costly livestock operations. Given that feeding usually accounts for the largest proportion of variable costs of livestock production, the role of locally produced high quality, high yielding perennial legumes in profitable small ruminant production is gaining popularity. One leading candidate is alfalfa (Medicago sativa L.) whose production in the southern USA, in recent years, has expanded due to increasing costs of fertilizers and transportation. Another major impediment to profitable small ruminant production in the US is infections by gastrointestinal nematodes (GIN), which reduce animal performance (Torres-Acosta and Hoste, 2008). Producers are in need of alternatives to chemical anthelmintic to satisfy the growing market demand. Stinging nettle (Urtica dioica), whose methanol leaf extract has shown higher potency as anthelmintic with notable health benefits to GIN-infected animals, is a bio-active forage that also detars herbivores due to its stinging properties. This project, therefore, seeks to generate data on sustainable forage-based gastro-intestinal parasite control using locally available bioactive forages that are protein-rich and not susceptible to depredation by wild ungulates and without using N fertilizers. Specifically, the project will assess effects of inter-seeding alfalfa into existing stinging nettle stands and that of maturity stages at harvest on the yield and quality of forage biomass, species composition and the health and performance of yearling meat goats supplemented with the pelletized bioactive forage mixture.
Animal Health Component
80%
Research Effort Categories
Basic
0%
Applied
80%
Developmental
20%
Goals / Objectives
This project seeks to generate data on sustainable forage-based gastro-intestinal nematodes (GIN) control using local bioactive forages that are protein-rich and not susceptible to depredation by wild ungulates and without using N fertilizers. Specifically, the project assesses effects of inter-growing alfalfa into existing stinging nettle stands and that of maturity stage at harvest on the yield and quality of forage biomass, and species composition. The project will also generate data on health and growth responses of yearling meat goats grazing in gamagrass pastures supplemented with pelletized stinging nettle-alfalfa forage mixtures. The information will be helpful to producers interested in climate-smart forage-based small ruminant production by promoting stinging nettle as a bioactive forage plant that can also deter depredatory deer damages to alfalfa in the region. Potentially, this innovative approach will also be helpful to dairy farmers interested in high-value forages that feed heavily on N, P, & K to minimize pollution of vulnerable water bodies.While inter-growing stinging nettle with compatible legumes may sustainably meet its N needs for vigorous growth, doing so with a highly nutritious and palatable type may ensure that the resulting forage mixture is of higher nutritional value and more acceptable to the animals. Furthermore, because animals can only consume stinging nettle if fed dry, the choice of legume to inter-grow with should also consider its suitability for quality haymaking, and similarities in shoot morphology and growth rate to allow for harvesting at the same time. However, although alfalfa is both a high quality and very palatable ruminant forage resource, there is paucity of information on how defoliation management may influence nutritive value of the forage mixture and/or subsequent species composition of the mixed stands. It is also not clear how species composition or maturity stage at harvest and the pelletizing process may affect the palatability, or anticipated health benefits of the stinging nettle-alfalfa forage mixture to small ruminants.
Project Methods
The study will be conducted at Virginia State University research farm in Chesterfield County, Virginia (37º 13" 43' N; 77 º 26" 22' W, 45 m above sea level). Three specific objectives will address (i) effects of growing season and growth stage at harvest on forage biomass production and nutritive value of stinging nettle and alfalfa mixed stands, (ii)effects of vegetative stage at harvesting of stinging nettle and alfalfa forage mixtures on their voluntary intake when pelletized, health and performance of naturally GIN-infected yearling meat goats grazing in gamagrass pastures, and (iii) effectiveness of intercropping alfalfa with stinging nettle in preventing forage yield losses to depredatory deer damages. The fourth objective seeks to promote the potential of stinging nettle intercropped with alfalfa as bioactive, high-value forage mixtures for integrated GIN control in climate-smart small ruminant production in Virginia using extention and outreach. In a field research on growth and forage production responses of stinging nettle intercropped with alfalfa to defoliation management, two stining nettle blocks established back in 2019 will be gap-filled using green-house raized poted cluster transplants and one interseeded with alfalfa. An adjacent block, about a third in size, will be planted in pure alfalfa at the same spacing within-rows but closer between-rows (30 cm). During the vegetation data collection phase, first two years, the field will be fenced to minimize potential effects of predatory deer damages.Subsequently, the pure stinging nettle and nettle-alfalfa (mixture) blocks will be divided into two, each assigned to early- or late-harvesting at begining of flowering and full bloom stages, respectively. There will be no difference of harvest dates for the alfalfa monoculture. At pelletizing, the alfalfa forage biomass will be balked and homogenized as a non-bioactive supplement control in the feeding trials. The resulting five pellet types will form six pelletized treatment rations; T1, Grazing + mixed early flowering stinging nettle-alfalfa, T2, Grazing + mixed late flowering stinging nettle-alfalfa, T3, Grazing + pure early flowering stinging nettle, T4, Grazing + pure late flowering stinging nettle, T5, Grazing + Higher rate pure late flowering stinging nettle, and T6, Grazing + pure alfalfa pellets. On every harvest event, the fresh forage biomass from each block will be air-dried on separate tarps, according to treatment, then stored in ventilated bags until processed into pellets. The air-dried material will be ground in a hammer mill then pelletized and stored at room temperature, in labeled parking bags ready for feeding trials. For each harvest lot, representative samples of milled material and the resulting pellets as well as their respective oven-dried grab samples will be ground to pass 1-mm sieve and later analyzed for nutritive value assessment.During the second growing season, changes in sward structure and species composition in the stinging nettle and alfalfa mixed stands harvested at different maturity stages in the preceding year will be assessed. Between harvest events, the rate of regrowth and forage buildup will be monitored by non-distractive biomass estimates using Sonar Automatic Pasture Reader by Naroaka Enterprises, 1188 Coalville Road, Narracan, Victoria 3824 Australia that determines pasture heights using light signals and calculate the available forage mass (kg DM ha-1). A day or two before the first spring and fall harvest in each year, data on vegetation structure will be recorded; sward heights (cm), every 60-cm and ground cover [the percentage of material other than bare ground covering the land surface (Anderson, 1986)] showing proportional contributions by stinging nettle, alfalfa, and weeds combined, within 1-m2 quadrats. before the first spring and fall harvests stand density -based on percentage light interception, from instantaneous proportions of photosynthetically active solar radiation (PAR) above the sward not reaching the ground will be recorded using the SunScan plant canopy analyzer system that also instantly calculates the respective leaf area index (LAI) values. As well, leaf chlorophyll concentration will be recorded using SPAD-502 chlorophyll meter from the recently fully expanded stinging nettle leaf and thus assess the likely benefit from N-fixation by the intercropped alfalfa.In two consecutive years, summer-time grazing trials, each involving 36 male growing goats on gamagrass pastures supplemented with pelletized stinging nettle, alfalfa or a mixture of the two will be conducted to assess effects of vegetative stage at harvest of pelletized stinging nettle and alfalfa forage mixtures on voluntary intake, health and performance of naturally GIN-infected yearling meat goats grazing in gamagrass pastures. Starting early June of each year, two groups of 18+ candidate animals will be separately introduced to the experimental pastures for a month-long acclimatization period of frequent grazing rotations including feeding off aCalan system-equiped mobile supplement feeder. From the fourth week of the acclimatization period, animals will be weighed and screened for GIN infection status based on FAMACHA scores, packed cell volume (PCV; microhematocrit method) and fecal egg counts according to Whitlock (1948), sensitivity of 50 eggs/g, on fecal samples collected directly from the rectum. FAMACHA scores will be recorded based on red coloration of the ocular mucous membranes (Kaplan, 2004). Additionally blood will be collected for baseline total serum proteins determination and overall immune health status. During the 60-d long collection period, 6-animal treatment groups will share the same grazing unit but with individual access to assigned treatment rations on the mobile feeder with specific rations corrected for differences in initial live body weight (LBW). Accordingly, animals on T5 will receive the same ration as for T4 but at about 50 % higher rates intended to confirm the potential of stinging nettle dose effect on the expected GIN control. The VSU herd's manager, in consultation with the resident veterinarian, will monitor the animals' health and administer treatment as needed with the same chemical anthelmintic in use at the farm and number of returns to treatment recorded so can be treated a response variable during statistical analyses. At the end of the live animal data collection period, three animals from each treatment group will be selected for humaine slaughter, after a 12h fast with ad libitum drinking water access, to assess treatment effects on the yield and quality of carcass and non-carcass components.During the third project year, the fence around the stinging nettle and alfalfa blocks will be removed so susceptibility to depredatory deer damages can be assessed using exclosures as control by comparing depredatory wildlife damages to alfalfa in pure stands Vs when intercropped with stinging nettle.Before each scheduled harvesting, depredatory damages on alfalfa will be scored in three 1-m2 quadrats along each of two peripheral harvest strips and a middle one. From each exclosure, stinging nettle and alfalfa row segments will be clipped into paper bags and processed as described above for yield estimation and quality assessment.The data collected will be analyzed using standard ANOVA for effects of species, intercropping, and maturity stage at harvest and that of pelletized rations on animal health and performance including initial LBW and GIN infection status as covariates, in the model. For the analyses, FEC data will be log-transformed, but results presented as means of the original data.