Non Technical Summary
Goats are increasingly popular with small landowners and fit well into forage-based production systems in the central United States, including Missouri. However, goats are acutely susceptible to infection by internal parasites. Traditionally, parasites have been controlled using commercial dewormers, but there are increasing concerns about parasite resistance to these chemicals. Thus, this research seeks to utilize the host animals natural or acquired immunity through a selection program to increase the level of parasite resistance.At the George Washington Carver Farm, a base population of does have been established, evaluated for resistance to internal parasites, and assigned to one of two selection lines: 1) high (high resistance to internal parasites) and 2) low (low resistance to internal parasites). Those does have been mated for three breeding seasons to corresponding high or low line bucks, which were purchased from various private breeders on the basis of parasite resistance. Resulting kids, from each line, are being selected based on parasite resistance and will be further crossed with high line and low line bucks, respectively, to produce the next generation of offspring. After this, lines will be closed. From then on, the most parasite resistant animals from the high line and the least parasite resistant animals from the low line will be mated within line and this will continue for several more generations. Typical production traits will continue to be recorded to determine the correlated response to selection for parasite resistance.Genetically selecting goats for improved parasite resistance may provide producers with a novel option for alleviating the negative effects of parasitism, may reduce commercial chemical dependence, and would be compatible with the modern trends toward sustainable agriculture. This research is part of a long-term selection project and is ongoing.

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
303	3820	1080	100%

Knowledge Area
303 - Genetic Improvement of Animals;

Subject Of Investigation
3820 - Goats, meat, and mohair;

Field Of Science
1080 - Genetics;

Goals / Objectives
Continued efforts at genetic selection of goats for improved parasite resistance can provide producers with a novel option for alleviating the negative effects of parasitism thereby reducing commercial anthelmintic dependence.1. To continue establishment of a parasite resistant line of goats.2. To calculate associations between FEC, PCV, and FAMACHA© scores in a closed line of Kiko × Boer goats. 3. To calculate genetic parameters for FEC, PCV, and FAMACHA© scores in a closed line of Kiko × Boer goats. 4.To determine the correlated response of selection for parasite resistance with production traits including kidding percentage, weight measures, and general health related traits.

Project Methods
Foundation herd establishmentDivergent breeding lines of Kiko (K) × Boer (B) goats, selected as kids for resistance or susceptibility to gastrointestinal parasites, were first established at the Lincoln University Carver Farm in 2011.Resulting F1 doe progeny from initial K × B matings were selected prior to the breeding season based on parasite resistance as determined by FEC EPD (described in detail later). Starting in 2012, and each year for 4 more years, the top 80% of F1 K × B doe kids from HL and bottom 80% of F1 K × B doe kids from LL, will continue to be backcrossed to unrelated HL and LL K bucks, respectively, to produce ¾ K × ¼ B progeny. Selection of F1 K × B does occurs from within line and no matings are made across lines. All F1 K × B buck kids will be removed from the experiment at weaning.Selected animalsAfter 3 years of ¾ K × ¼ B foundation individuals are produced, lines will be closed. From then on and starting in 2014, the 4 (2 as alternates) most parasite resistant ¾ K × ¼ B buck kids from HL and the 4 (2 as alternates) least parasite resistant ¾ K × ¼ B buck kids from LL, will be mated, within line, to the top 80% most parasite resistant ¾ K × ¼ B doe kids from HL and the top 80% least parasite resistant ¾ K × ¼ B doe kids from LL. All animals will be selected based on FEC EPD. Selected ¾ K × ¼ B bucks will be used for one breeding season only, and then removed from the experiment.After producing one set of kids, the 60% most parasite resistant ¾ K × ¼ B does from HL and the 60% least parasite resistant ¾ K × ¼ B does from LL will be retained and mated to the corresponding and most recent generation of ¾ K × ¼ B bucks to produce an additional set of kids. Removal from the experiment will occur in the remaining does after producing one crop of kids and will occur in the further selected does after producing a second crop of kids. As a consequence, each line will eventually stabilize and consist of ¾ K × ¼ B does from the most current generation, and further selected ¾ K × ¼ B does from the preceding generation.Selection procedures Bucks and does will continue to be selected each fall, prior to the breeding season, based on FEC EPD. Multiple FEC measurements will be taken in an effort to improve accuracy of selection decisions, because of environmental conditions associated with traits such as FEC (Falkoner and Mackay, 1996). Fecal egg counts, FAMACHA© scores, and PCV values will be measured monthly (or more often as necessary), beginning at weaning in August, until just prior to selection and breeding in December. Selection will be based on FEC EPD calculated from data taken at a minimum of 4 different times. In the event that an animal meets 2 of the following: a FEC of 4,000 eggs per g, a FAMACHA© score of 4 or 5, or a PCV value ≤ 21%, then those animals will be immediately treated with commercial anthelmintic and subsequent FEC data will not be included in the selection criteria. Rather, those animals will be selected on the basis of the number of times treated rather than FEC data. In the case of treatment in HL goats, selected individuals will be those that have been treated the fewest times or have the lowest FEC EPD and in the case of treatment in LL goats, selected individuals will be those that have been treated the most times or have the highest FEC EPD.Four bucks (2 as alternates) that are the most parasite resistant within HL and 4 (2 as alternates) bucks that are the least parasite resistant in LL will be selected via FEC EPD for use each generation. No other criteria will be used for selection of bucks. Selected bucks will only be used for one season. Does will be selected on the same basis as bucks. Doe selection will be based solely on parasite resistance; no other selection criteria will be followed with the exception of removal of does based on pregnancy status. After producing one crop of kids, the 60% most parasite resistant ¾ K × ¼ B does from HL and the 60% least parasite resistant ¾ K × ¼ B does from LL will produce an additional crop of kids. Removal from the experiment will occur in the remaining does after producing one crop of kids, and will occur in the further selected does after producing a second crop of kids.Animal managementDoes will be managed as one group throughout the year, except at breeding when they will be assigned to breeding pens based on line. Within line, does will be assigned to 1 of 2 breeding pens with 1 buck each, with the only restriction being that inbreeding is minimized. The breeding season will be from approximately December 1 to January 31, annually. During the breeding season, does will be allowed access to pasture composed predominately of tall-fescue and will be supplemented at NRC (2006) recommended levels. Following the breeding season, bucks will be removed from the experiment (they will be retained until the following year when the next generation of buck kids will formerly replace them). Pregnancy status will be determined via ultrasound by a trained technician within 45 days post breeding. At that time, open does will be removed from the experiment.Does will be wintered on mixed-grass hay and supplemented at NRC (2006) recommended levels. Kidding will occur in May on pasture. Kids will be ear-tagged, weighed, and given a Vitamin E shot within 24 h of birth. Starting at 2 wk of age, kids will be allowed access to a 20% crude protein, corn-soybean meal-based creep, fed until weaning at approximately 90 d of age. At that time, kids will be sorted by sex and will be moved to separate tall fescue-based paddocks with additional supplementation (NRC, 2006) provided. Selected does will also be moved to tall fescue-based paddocks with supplementation at NRC (2006) recommended levels, and will be maintained until the following breeding season; other, unselected does, will be removed from the experiment. Typical health and vaccination protocols will be followed at all times for does, bucks, and kids.Sampling proceduresKids will be tagged and recorded at birth (to ensure accuracy of doe and sire pedigrees). Production traits that will be measured include: kidding percentage, kid birth weight, and kid weaning weight. Also, the number of morbidity and mortality cases will be recorded for kids and breeding goats. Additionally, weights and body condition scores will be monitored on breeding goats periodically.Weights, fecal samples, blood samples, and FAMACHA© scores will be collected and recorded at 30-d intervals from weaning in August, until November, just prior to when selections decisions are made. Approximately 5 g of feces will be collected from the rectum to estimate FEC. Fecal egg counts will be determined on 2 g of feces using the modified McMaster's technique (Whitlock, 1948) with the precision of each egg counted representing 50 eggs per gram of feces. Blood samples will be collected via jugular venipuncture using evacuated sample collection tubes containing an anticoagullent (such as ACD) and 18 gauge needles to estimate PCV. Packed cell volume will be determined by the micro-hematocrit centrifuge method. Also, FAMACHA© scores will be recorded as 1 (red, non-anemic), 2 (red-pink, non-anemic), 3 (pink, mild-anemic), 4 (pink-white, anemic), or 5 (white, severely anemic).