Genetic Resistance of Barbari and Jamunapari Kids to Natural Infection with Gastrointestinal Nematodes

An investigation was made in 252 Barbari and Jamunapari kids to assess their resistance to natural infection with gastrointestinal (GI) nematodes and to establish indicator traits for such resistance in Indian goats. The indicator traits, faecal egg counts (FEC) and packed cell volume (PCV) were affected by various genetic and non-genetic factors. There were no breed differences in the FEC or PCV at 3, 6 or 9 months of age. Jamunapari male kids had a higher FEC than the female kids at 6 months of age. However, Barbari female kids had a higher FEC than the respective male kids at 9 months of age. At 6 months of age in both breeds, the kids born in the spring (March–April) had a higher FEC than those born in the autumn (October–November). The FEC of kids at 9 months of age was higher than at 3 or 6 months of age. Sire had a significant effect on PCV at 6 and 9 months of age. The kids born in the autumn had a higher PCV than those born in the spring. The PCV of male Barbari kids differed significantly from that of female kids at all the ages. The correlation coefficient of FEC on both body weight and body weight gain was negative, and there was a loss of body weight in the individuals with a high FEC.     

Genetic parameters for body weight, reproduction, and parasite resistance traits in the Creole goat

We estimated the genetic parameters for BW, reproduction, and parasite resistance traits to implement a breeding program for the Creole goat. The traits were preweaning BW at 70 d of age (BW70d), BW at 11 mo of age (BW11), fecal egg count at 11 mo of age (FEC11) for all animals, packed cell volumes of lactating does (PCV), and their fertility (FER) and litter size (LS). We analyzed about 30 yr of data, which included 18,450 records on 11,970 animals from the INRA experimental flock in Guadeloupe (French West Indies). Heritability estimates were low for reproduction traits (0.11 ± 0.02 for LS and FER) to moderate for production traits (0.32 ± 0.03 for BW11; 0.20 ± 0.03 and 0.08 ± 0.02 for the direct and maternal heritability estimates of BW70d, respectively). Heritability estimates for gastrointestinal nematode resistance traits were situated in an intermediate range (0.13 ± 0.05 for PCV and 0.18 ± 0.04 for FEC11). Genetic correlations between FER, PCV, BW11, and the maternal effect of BW70d were altogether positive, whereas LS and FEC11 were almost uncorrelated phenotypically and genetically. These correlations are very favorable for setting up a breeding program, making it possible to improve BW, reproduction, and parasite resistance traits simultaneously.     

Variability of resistance in goats infected with Haemonchus contortus in Brazil

The variability between and within breeds with respect to nematode egg counts (EPG), packed cell volume (PCV) and hemoglobin (Hb) was studied in 36 yearling female goats of the Caninde (15), Bhuj (6) and Anglo-Nubian (15) breeds, exposed to Haemonchus contortus. Nematode-free goats were turned to a contaminated paddock in late February. From then on, fecal egg per gram counts (EPG), packed cell volume (PCV) and hemoglobin (Hb) were determined at 2-week intervals up to Week 18. The EPG, transformed as [log(EPG + 75)], varied (P < 0.01) between goats within breeds and between weeks of exposure, but not between goat breeds (P > 0.05). PCV and Hb were affected by goat breeds (P < 0.05), by goats within breeds (P < 0.01) and by weeks of exposure (P < 0.01). Anglo-Nubians had higher (P < 0.01) PCV and Hb than Caninde; Bhuj had intermediate values. There were two EPG rises; one between Weeks 6 and 10 and the other between Weeks 14 and 16. The within breed variability was marked during the EPG rise on Week 6, when individual egg counts ranged from 130 to 2500. The EPG rises coincided with drops in Hb. PCV presented a similar trend, though not as marked. Haemonchus was responsible for more than 95% of nematode eggs counted. Considering the goat as experimental unit, the correlation coefficients (r) were: -0.45, P = 0.0064, between log(EPG + 75) and PCV; and -0.53, P = 0.0009, between log(EPG + 75) and Hb. The negative correlation between egg counts and blood values suggested breed differences in PCV and Hb were related to resistance to H. contortus infection and/or to its effects.     

Impact on productivity of peri-parturient rise in fecal egg counts in Creole goats in the humid tropics

The control of gastrointestinal nematodes requires an understanding of their epidemiology so that particular parasite stages can be targeted. Dam infection during early lactation is one example of this in ruminant nematode infections. The existence of the peri-parturient relaxation in immunity and its impact on productivity were examined in a Creole goat flock from Guadeloupe, exposed to mixed natural infection (predominantly Haemonchus contortus and Trichostrongylus colubriformis). A total of 1,511 l were obtained from 909 does resulting from 463 dams and 150 sires. Fecal and blood samples were collected at kidding before anthelmintic drenching, 4 and 6 weeks after kidding. The traits analyzed were logarithm transformed fecal egg counts (FEC), packed cell volume (PCV), and logarithm transformed blood eosinophilia counts (EOS) for does at each sampling point and changes in these during the postpartum period. With the exception of the PCV values measured at kidding, lactating does had significantly higher FEC and lower PCV than control dry does at every sampling point. Geometric means of FEC in lactating does were 819 +/- 174, 677 +/- 146 and, 699 +/- 160 eggs per gram (EPG) at kidding, 4 and 6 weeks after kidding respectively. Geometric means of FEC in dry does were 187 +/- 57, 89 +/- 28, 133 +/- 43 at these time points, respectively. EOS differences were not consistent between groups and probably not specific enough for variations in Creole goats' peri-parturient rise to be discussed. As does aged, their egg output decreased and primiparous does always had greater egg output than multiparous ones. Overall, does' FEC at 4 weeks after kidding decreased by 1.3% each year. The higher the litter size, the higher the FEC at kidding and inverse applied for PCV measurements. Does that stopped lactating had significantly lower FEC and higher PCV values than lactating does with low milk yields. Higher infection rates during early lactation in Creole goats were recorded in does with lower maternal ability assessed by the average daily weight gain of kids between 10 and 30 days of age. Kids from dams with higher FEC (i.e. >600 EPG higher than corresponding does) had 17% lower average daily weight gain between 30 and 70 days postpartum and were approximately 1 kg lighter at weaning than kids from dams with lower FEC. Thus, it is clear that a peri-parturient rise in FEC exists in Creole goats. By controlling the intensity of this peri-parturient rise in FEC, herd health and productivity could be substantially improved.     

Segregation of natural and experimental gastrointestinal nematode infection in F2 progeny of susceptible Suffolk and resistant Gulf Coast Native sheep and its usefulness in assessment of genetic variation

Gastrointestinal nematode parasitism is a concern to small ruminants worldwide. Productivity has been compromised because such nematodes, particularly Haemonchus contortus, have developed resistance to available anthelmintics. Some sheep breeds and lines within breeds are relatively resistant to infection, a trait that may be useful for developing control strategies. Suffolk sheep, which are susceptible to infection, were crossed with Gulf Coast Native sheep, which are more resistant to infection, to produce F1 progeny. F1 rams were bred to F1 ewes which produced 227 F2 offspring. These F2 offspring were evaluated for variability in infection levels, based on fecal egg count (FEC) and blood packed cell volume (PCV), under two natural infection conditions (one at weaning and another after a summer grazing period) and one experimental infection. The range of both FEC and PCV was large for all three infection periods with annual variation. Overall, the range for the three infection periods, respectively, were 167-149,933, 0-31,400 and 17-114,667 eggs per gram (EPG) of feces and 8.7-37.0%, 7.3-33.0% and 8.3-36.0%. This segregation of infection is what would be expected of F(2) progeny from susceptible and resistant parent breeds. Heritabilities of FEC and PCV for the three infection periods, respectively, were 0.15, 0.29 and 0.12, and 0.11, 0.22 and 0.12. Based on segregation of infection, larger heritabilities and maternal environment effects that declined after weaning, the summer natural infection was probably the best model for assessing genetic variation.     

Genetic analysis of the potential role of IgA and IgE responses against Haemonchus contortus in parasite resistance of Creole goats

Small ruminants are affected by gastrointestinal nematode (GIN) infection. A promising alternative strategy for control of GIN infection is to increase the level of resistance in the population by taking advantage of the host's immune response. Immunoglobulin A (IgA) and E (IgE) are known to be involved in immune response to GIN. The aim of this study was thus to investigate genetic parameters of IgA and IgE responses against Haemonchus contortus in Creole kids naturally challenged at pasture and to determine the relationship with other resistance criteria such as faecal egg counts, packed-cell volume, eosinophil counts and bodyweight. Variance and covariance components for genetic and residuals effects for each trait were estimated on 3862 males at 11 months of age. Heritability estimates for IgA and IgE ranged between 0.15 and 0.57. Strong positive genetic correlations were observed between either IgE or IgA responses against L3 and adult excretory/secretory products (ESP) antigens of H. contortus, suggesting that the humoral immune response is not specific to the life cycle stage of the parasite suggesting that there is substantial cross recognition between the different parasite antigens. Heritability estimates for faecal egg count (FEC), packed-cell volume (PCV) and bodyweight (BW) were in accordance with previous results in Creole kids. Blood eosinophil counts were found moderately heritable and negatively correlated with FEC, suggesting that this cell population plays a role in resistance to nematode parasite infection in Creole goats. IgA response was positively correlated to FEC, in contrast with the negative correlation between IgE against L3 of H. contortus and FEC. In Creole goats, IgA response against L3 or ESP of H. contortus would rather be associated with the worm burden than an immune protective response. The immune response involving activity of IgE against L3 of H. contortus may be one important pathway for development of resistance to gastrointestinal nematode infections in Creole goats.     

Expression of acquired immunity to a local isolate of Haemonchus contortus by the Nigerian West African Dwarf goat.

The capacity of young Nigerian West African Dwarf (WAD) goats to express good acquired immunity to their native geographic strain of Haemonchus contortus and the correlates of this responsiveness were studied in a laboratory experiment involving forty 7-8 month old kids. A primary immunising infection with 2000 L3 (equivalent to 260-450 L3/kg body weight) with or without challenge on D42 with 2000 L3 resulted in a mild chronic infection with a pre-patent period of 18-20 days and little or no reduction in worm burden between D14 and D56. In contrast, another group (D) of kids, whose immunising infection had been truncated with fenbendazole on D35 and later received similar challenge infection, developed good protection against challenge. Thus, worm burdens were largest in group E (challenge control), larger in group C (primary+challenge) and least in group D. Of the measures of infection used, namely faecal worm egg counts (FECs), circulating eosinophil (EOS) responses, packed cell volume (PCV) and body weight, FEC and EOS responses exhibited marked individual variability, but only FEC (geometric mean of transformed counts) and PCV showed strong correlation with worm burden. There was also a significant negative correlation between FEC and PCV. The size of inoculum used was well tolerated by the kids, as it induced only mild changes in PCV in some goats and no effect at all on body weights. This suggests that the WAD goat may possess a good measure of resistance to the pathogenic effects of its native strain of H. contortus. The wide individual variability in FEC and its strong relationships to worm burden and PCV are pointers to its likely genetic basis. There are, therefore, good prospects for further studies to identify H. contortus resistant genotypes among the WAD goat population.     

Inheritance of fecal egg count and packed cell volume and their relationship with production traits in sheep infected with Haemonchus contortus

This study describes responses to artificial infection with Haemonchus contortus in ewes and lambs of 50% Dorset, 25% Rambouillet, and 25% Finn-sheep ancestry and provides estimates of genetic parameters for measures of parasite resistance. One hundred ninety-eight ewes out of 64 sires, and 386 lambs out of 25 sires were evaluated in autumn and spring of 2 yr. Ewes were dewormed shortly after weaning their lambs and lambs were dewormed at about 120 d of age. One week after deworming, ewes and lambs were dosed with approximately 10,000 infective larvae of H. contortus. After infection, BW, fecal egg counts (FEC), and packed cell volume (PCV) were measured weekly for 7 wk in lambs kept in drylot and fortnightly for 11 wk in ewes on pasture. Summary traits were defined as initial PCV, mean BW across all times, and means for PCV (MPCV) and log-transformed FEC (MLFEC) at wk 3 to 7 after infection for lambs and wk 3 to 11 after infection for ewes. Ewes and lambs did not lose weight overall in any year or season, but there was no consistent effect of year or lambing season on mean LFEC or mean PCV during infection in either ewes or lambs. Yearling ewes were less resistant to infection than older ewes, with lower PCV (P < 0.05) and higher LFEC (P < 0.05). During infection, PCV was positively correlated with BW and negatively correlated with LFEC in both ewes and lambs. In lambs, heritabilities were 0.39 (P < 0.01) for PCV, 0.10 (P < 0.05) for LFEC across all measurement times, and 0.19 (P < 0.01) for three measures of LFEC taken at the peak of infection. Heritability estimates for ewes were 0.15 (P < 0.05) for PCV and 0.31 (P < 0.01) for LFEC. Repeatabilities for LFEC and PCV across measurement times were moderate in ewes and lambs. Correlations between dam and lamb records for MLFEC were generally low, suggesting different mechanisms of resistance in lambs and nonlactating ewes. Ewes with higher genetic merit for growth as lambs were less resistant to infection as adults, but genetic merit for fertility and prolificacy were not related to parasite resistance. Lambs with higher genetic merit for body weight were more resistant to infection. Selection for resistance to H. contortus is therefore possible and should not adversely affect growth of lambs and fertility of ewes in this production environment.     

Use of copper oxide wire particles to control gastrointestinal nematodes in goats

The objectives of these experiments were to determine the optimal dose of copper oxide wire particles (COWP) necessary to reduce gastrointestinal nematode (GIN) infection in young and mature goats naturally infected with Haemonchus contortus or a mixed infection and to determine whether the effectiveness could be enhanced through feeding management. Two experiments were conducted during cooler months in Georgia, and 4 experiments were conducted during warmer spring or summer months in Arkansas. Meat goats received 0 up to 10 g of COWP under a variety of management conditions. In all experiments, blood and feces were collected every 3 or 7 d from 6 to 42 d to determine blood packed cell volume (PCV) and fecal egg counts (FEC) to estimate the degree of GIN infection. In mature goats grazing fall pasture, mean FEC of 0 g of COWP-treated goats increased, and those of 4 g of COWP-treated goats remained low on d 0, 7, and 14 (COWP x d, P < 0.03), and FEC decreased on these days (P < 0.001). In 5 and 10 g of COWP-treated goats, PCV increased (P < 0.001), but FEC and PCV remained unchanged over time in control goats. Fecal egg counts were similar among all low doses (0.5, 1, 2, 4 g) of COWP administered to weaned kids for all dates examined (P > 0.10), which were lower on d 7 through 21 (COWP x date, P < 0.05) but similar by d 28, compared with FEC of 0 g of COWP-treated kids. Packed cell volume was lower in 0 g compared with all COWP-treated kids by d 14 (COWP x date, P < 0.05). Feeding management in combination with COWP for GIN control had little effect compared with COWP alone for these short-term studies. In conclusion, a dose of COWP as low as 0.5 g, which was considered optimal to reduce the risk of copper toxicity, was effective in reducing FEC in young goats, and 5 g of COWP was effective in older goats. Copper oxide does not appear to be effective in controlling newly acquired L4 stage (preadult) larvae, which also feed on blood, leading to decreased PCV in newly infected goats.     

川渝部分山羊品种(类群)遗传多样性微卫星标记研究

为分析川渝山羊品种(类群)的遗传多样性和系统发生关系,利用30个微卫星标记,对6个山羊品种(类群)进行分析。结果表明:金堂黑山羊遗传多样性最丰富,群体多态信息含量、平均杂合度和有效等位基因数分别为0.777、0.819和6.54;大足黑山羊各项指标最低,分别为0.736、0.787和5.57。对6个品种(类群)聚类分析表明,金堂黑山羊与南江黄羊的首先聚类在一起,然后依次与板角山羊、川东白山羊、大足黑山羊和波尔山羊聚类。各山羊品种(类群)的聚类关系与其来源、育成史及地理分布基本一致。     

High genetic correlation between resistance to Haemonchus contortus and to Trichostrongylus colubriformis in INRA 401 sheep

To compare the protection acquired by infection with Haemonchus contortus or Trichostrongylus colubriformis, successive cross infections with the two species were conducted in two genetically similar groups of 150 ewe lambs from 30 sires of INRA 401 breed. At 6 and 7.5 months of age, each group received two doses of 10000 L3 separated by a treatment of one of the species, followed by a similar infection with the second species at 9 and 11.5 months. Faecal egg counts (FECs) were done 28 and 35 days after each dose. There were very high genetic correlation within and between species suggesting that the environmental conditions were very similar. The heritability of FEC of H. contortus ranged from 0.39 to 0.48 and the genetic correlations between FEC after the first and second infections with the same or different species were all near 1. Selection against this species could be done on the response to only one dose. For T. colubriformis, only the response to challenge infection had a similar heritability (0.47); the genetic correlations within and among species were also near one. These results will assist the selection of sheep resistant to nematode parasites.     

Genetic parameters for resistance to Haemonchus contortus in Merino sheep in South Africa

Resistance to natural infections of Haemonchus contortus (wireworm) was studied in Merino sheep. From February 1995 to July 1996 data were collected from the OTK Merino Stud on the farm Wildebeesfontein near Hendrina in Mpumalanga province. From March 1998 to January 2000 another Merino flock at Irene in Gauteng province was included in the study. In both cases, 50 randomly-chosen animals from each group of lambs weaned were sampled weekly for faecal egg count (FEC) until a mean of 2500 eggs per gram faeces (epg) was reached. At this stage, all lambs in the group were sampled for FEC, packed cell volume (PCV) and live mass in the case of the Wildebeesfontein flock. Animals were monitored from weaning to about 1 year of age. Data from 5 different groups of lambs (583 animals and 1722 records in total) with genetic links were accumulated and analysed. Variance components and resulting heritabilities for logFEC and PCV were estimated using a bivariate animal model with repeated records. The estimated heritabilities were 0.24 +/- 0.02 for logFEC and 0.14 +/- 0.02 for PCV. A strong negative correlation (-0.84 +/- 0.06) existed between the 2 traits. The genetic correlation between PCV and live mass for the Wildebeesfontein flock was low (0.28 +/- 0.09), while that between logFEC and live mass was negative, although not significantly different from zero (-0.13 +/- 0.09). These results suggest that FEC can be used as a selection criterion for resistance to H. contortus infections in Merino sheep.     

Faecal egg counts in Angora goats following natural or experimental challenge with nematode parasites: within-flock variability and repeatabilities.

Phenotypic variation in faecal worm-egg count (FEC) was studied in 100 Angora goats between 6 months and 2 years old as part of a wider investigation into the potential use of FEC as a selection trait in breeding goats for improved natural resistance to nematode infection. Shortly after weaning at 4-5 months old the goats were subjected to a procedure involving successive natural and experimental challenges, which was continued at 6-monthly intervals until the goats were 2 years old. Experimental challenges consisted of Trichostrongylus colubriformis infective larvae administered orally at a dose rate of 1000 larvae/kg liveweight. FECs resulting from both natural and experimental infections varied considerably between individual goats as well as between different sampling times. Mixed model analysis of variance of natural infections confirmed that a significant component of this variation was attributable to differences between individual goats (P < 0.01) as opposed to other potential sources of variability, indicating that although generally deemed to be more susceptible than sheep, Angora goats do nevertheless vary in their ability to resist nematode infection. Rank correlations between pairs of FECs derived from the same infection were relatively high for both natural and experimental infections (r = 0.63-0.70 and 0.54-0.79, respectively; all P < 0.01). However, those between mean FECs measured on successive 6-monthly sampling occasions were considerably lower and more variable (r = 0.01-0.41 and 0.19-0.62 for natural and experimental infections, respectively). Nevertheless, FECs resulting from natural infections showed moderate correlations with those from corresponding experimental infections (P < 0.01) on all except the first sampling occasion (r = 0.23-0.61). Correlations were marginally higher when FECs from experimental infections were adjusted for infecting dose size (r = 0.32-0.63). FECs resulting from experimental infections were significantly higher on the first sampling occasion (at 6 months) than on subsequent occasions (P < 0.01) suggesting that some degree of resistance to nematode establishment had developed in the goats by 12 months old. On the basis of unadjusted FECs there appeared to be no marked increase in resistance beyond that age, although analyses based on FECs adjusted for infecting dose size suggested an increase in acquired resistance up to 18 months of age. FECs following natural challenge in goats which had also received experimental infections were not significantly different from those exposed only to natural challenge, indicating that the drench-abbreviated experimental infections had had no immunizing effect. Does that had given birth and were lactating at 24 months had significantly higher FECs than 'dry' does in the flock (P < 0.01), suggesting that like sheep, goats exhibit a post-parturient relaxation of immunity. The use of FECs as potential indicators of resistance status in goats and as a criterion for the selection of breeding animals is discussed.     

基于线粒体DNA D-loop区序列分析中国及新西兰奶山羊遗传进化关系

[目的]分析我国地方培育奶山羊品种与国外引进品种的遗传进化关系。[方法]以4个国内奶山羊品种（文登奶山羊、关中奶山羊、崂山奶山羊、雅安奶山羊）和3个新西兰引进奶山羊品种（阿尔卑斯奶山羊、吐根堡奶山羊、萨能奶山羊）为研究对象,采集33只个体的外周血样本,提取血液基因组DNA,利用PCR法扩增线粒体DNA（mitochondrial DNA,mtDNA）D-loop区全长序列,对测序获得的序列进行生物信息学分析,探究不同奶山羊品种的遗传多样性及进化关系。[结果]7个品种奶山羊的mtDNA D-loop区中A、T碱基含量高于G、C碱基含量。共检测到82个多态位点,25个单一多态位点,55个简约信息位点。各品种单倍型多样度（Hd）范围为0.905~1.000,核苷酸多样度（Pi）范围为0.001 51~0.013 32;共存在26种单倍型,文登奶山羊和萨能奶山羊各有5个单倍型,阿尔卑斯奶山羊有4个单倍型,崂山奶山羊、吐根堡奶山羊、关中奶山羊、雅安奶山羊各有3个单倍型;各品种核苷酸平均差异数（K_XY）范围为6.400 00~38.450 00,核苷酸歧异度（D_XY）范围为0.005 79~0.034 76,遗传分化系数（G_ST）范围为0.000 00~0.186 05,遗传分化指数（F_ST）范围为0.231 56~0.971 52。品种间系统发育树表明,文登奶山羊和崂山奶山羊聚为一支;关中奶山羊与3种新西兰奶山羊遗传距离较近,从遗传学角度证实了关中奶山羊由国外奶山羊与地方品种经杂交选育而成;雅安奶山羊与其他品种遗传距离最远。[结论]中国奶山羊存在2个支系起源且未发现群体扩张;中国培育奶山羊品种含有较多的国外奶山羊血统;文登奶山羊与崂山奶山羊亲缘关系较近,雅安奶山羊在遗传进化中可能存在地域隔离。     

Genetic relationship of body measurement traits at early age with carcass traits in Japanese black cattle

Estimates of genetic parameters were obtained for body measurement traits of 648 animals at 4 months of age, of 545 at 8 months and carcass traits of 14 972 animals with the use of an animal model by the restricted maximum likelihood procedure. The estimated heritabilities for carcass traits were high (0.41 to 0.54). At 4 months the estimated direct heritabilities for body measurement traits were moderate to high (0.28 to 0.64), except for chest width (0.19); at 8 months they were also moderate to high (0.23 to 0.49), except for chest depth and chest width (0.18 and 0.06, respectively). Maternal heritabilities for all body measurement traits were low at both ages. The results indicate that because of their moderate direct genetic correlations with body measurement traits, carcass weight, rib thickness and subcutaneous fat thickness can be improved; however, rib eye area and beef marbling standard show little such possibility considering their correlation with body measurement traits.     

Validation of the FAMACHA eye color chart for detecting clinical anemia in sheep and goats on farms in the southern United States

Recent studies on sheep and goat farms in the southern United States indicate that multiple-anthelmintic resistance in Haemonchus contortus is becoming a severe problem. Though many factors are involved in the evolution of resistance, the proportion of the parasite population under drug selection is believed to be the single most important factor influencing how rapidly resistance develops. Therefore, where prevention of resistance is an important parallel goal of worm control, it is recommended to leave a portion of the animals untreated. Recently, a novel system called FAMACHA was developed in South Africa, which enables clinical identification of anemic sheep and goats. When H. contortus is the primary parasitic pathogen, this system can be applied on the farm level to reduce the number of treatments administered, thereby increasing the proportion of the worm population in refugia. Since most studies validating the FAMACHA method have been performed in South Africa, it is important that the method be tested in other regions before its use is broadly recommended. We performed a validation study of FAMACHA by testing the system in sheep (n = 847) and goats (n = 537) of various breeds and ages from 39 farms located in Arkansas, Georgia, Louisiana, Florida, and the US Virgin Islands. The color of the ocular conjunctiva of all animals were scored on a 1-5 scale using the FAMACHA card, and blood samples were collected from each animal for determination of packed cell volume (PCV). Fecal samples were also collected from a majority of the animals tested for performance of fecal egg counts (FEC). Correlations between PCV and eye scores, PCV and FEC, and FEC and eye scores were all highly significant for both sheep and goats (P < 0.001). Data for both FAMACHA scores and PCV were evaluated using two separate criteria for anemia: eye score values of 3, 4 and 5 or 4 and 5, and PCV values of < or =19 or < or =15 were considered anemic. Specificity was maximized when eye score values of 4 and 5 were considered anemic and PCV cut off for anemia was < or =19, but sensitivity was low. In contrast, sensitivity was 100% for both sheep and goats when eye score values of 3, 4 and 5 were considered anemic and PCV cut off was < or =15, but specificity was low. In both sheep and goats, predictive value of a negative was greater than 92% for all anemia and eye score categories, and was greater than 99% for both eye score categories when an anemia cutoff of < or =15 was used. Predictive value of a positive test was low under all criteria indicating that many non-anemic animals would be treated using this system. However, compared to conventional dosing practices where all animals are treated, a large proportion of animals would still be left untreated. These data indicate that the FAMACHA method is an extremely useful tool for identifying anemic sheep and goats in the southern US and US Virgin Islands. However, further studies are required to determine optimal strategies for incorporating FAMACHA-based selective treatment protocols into integrated nematode control programs.     

Health and productivity of traditionally managed Djallonke sheep and West African dwarf goats under high and moderate trypanosomosis risk.

Trypanosome infections, packed red cell volume levels (PCV), body weight and nematode faecal egg counts of village-based small ruminants were monitored in two areas in The Gambia with either moderate or high trypanosomosis risk for 24 and 30 months respectively. Outflows from the flock and new-born animals were recorded and data on housing and management were compiled. Reported mortality rates were higher in goats than in sheep, but for both species highest in the moderate risk area. The peak of trypanosome infections lagged the peak of tsetse densities by 1-3 months in both areas. Trypanosoma vivax was the predominant species found in the infected animals, followed by T. congolense. Trypanosome prevalence was, in general, higher in sheep than in goats but only significantly higher during Year 1 in the moderate risk area. Trypanosome infection reduced the PCV level significantly and seasonal effects indicated significantly lower PCV levels during the rains. Trypanosome infection significantly depressed weight gain in both species at periods where infection rates were highest. In both species considerably lower weight gains were observed during the rainy season. Abortion rates were higher in goats than in sheep in both study sites, and highest in the high-risk site. Trypanosome infection in ewes in the high risk area increased lamb mortality significantly but had no effect on birth weights, nor on growth rates up to 4 months. Offspring mortality up to 4 months was generally high at both sites. Trypanosome infection in the dam between 3.5 to 7 months post parturition significantly increased parturition interval in both species. Peak faecal egg output occurred at the end of the rainy season and was highest for both species in the moderate risk site. Poor grazing management was found responsible for a seasonal nutritional constraint. Based on these results, these breeds of sheep and goats can be considered as trypanotolerant since they are able to remain productive under high and moderate levels of trypanosome challenge. Nevertheless, trypanosomosis affected their health and production level as shown by reduced PCV levels, depressed weight gains, longer parturition intervals and higher lamb mortality. In addition, during the rains, helminth infections and poor management leading to nutritional constraints had also a negative impact on health and production and therefore influenced the innate resilience to trypanosomosis in those indigenous breeds. Adaptations in management may have an equal impact as certain disease control measures to improve biological and economical returns from small ruminants in tsetse infested rural areas.     

四川5个山(绵)羊品种随机扩增多态DNA分析

本研究参阅文献挑选 80个随机引物 ,从中筛选出 3 0个重复性好的引物 ,对四川黑山羊、南江黄羊、北川白山羊、成都麻羊 4个山羊品种和藏绵羊进行RAPD分析 ,并进一步对 1 3只南江黄羊个体 ,1 8只黑山羊个体的基因组DNA进行PCR扩增。用Nei氏公式计算品种间的遗传距离 ,用UPGMA法构建树状聚类图。结果表明 :黑山羊与南江黄羊的遗传距离最小 ,亲缘关系较近 ;藏绵羊与各品种间的遗传距离都很大 ,亲缘关系远 ;RAPD技术可作为一种有效的分子标记用于山羊品种之间遗传亲缘关系的分析     

Sericea lespedeza hay as a natural deworming agent against gastrointestinal nematode infection in goats

Infection with gastrointestinal nematodes (GIN), particularly Haemonchus contortus, is the biggest constraint to profitable goat production in the United States (US). Due to widespread prevalence of anthelmintic resistance in goat GIN, alternative, non-chemical control methodologies are needed to increase profitability of small ruminant industries. A study was designed to test the efficacy of a high condensed tannin (CT) legume, sericea lespedeza [SL, Lespedeza cuneata (Dum.-Cours. G. Don)] against GIN of goats fed in confinement. The goats were given a trickle infection of 500 H. contortus larvae/animal three times per week during the trial to simulate natural infection. Twenty Boer bucks (6-8 months old) were fed bermudagrass [BG, Cynodon dactylon (L.) Pers.] hay plus concentrate for 5 weeks in confinement and then 10 animals were switched to SL hay for an additional 7 weeks. Throughout the trial, feces and blood were collected weekly from individual animals to determine fecal egg count (FEC) and blood packed cell volume (PCV). Fecal cultures were made weekly from pooled samples to determine treatment effects on GIN larval development. All goats were slaughtered at the end of the trial, with adult worms in the abomasum and small intestine of each goat recovered, counted, and identified to species. Feeding SL hay to goats significantly (P<0.01) reduced FEC and increased PCV compared with BG hay. In addition, a lower percentage of ova in feces from SL-fed goats developed into infective (L3) larvae. There was a direct effect of SL hay on adult worms, with significantly (P<0.01) lower numbers of both abomasal (H. contortus, Teladorsagia circumcincta) and small intestinal (Trichostrongylus colubriformis) nematodes compared with goats fed BG hay. Feeding SL hay to goats is an effective means of controlling parasitic nematodes and may be a potential supplement/replacement for chemical anthelmintics.     

Epidemiological observations and heterosis analysis of gastrointestinal nematode parasitism in Suffolk, Gulf Coast Native, and crossbred lambs.

A crossbreeding program was conducted to evaluate the resistant status to gastrointestinal nematode parasite infection in crossbred (F1) lambs and their Suffolk and Gulf Coast Native (Native) breed counterparts. A total of 253 lambs were included in the study over 2 years. Fecal egg count (FEC) and blood packed cell volume (PCV) of 18-20 monitor lambs of each breed group in each year were collected every other week from birth to 24-30 weeks of age. The FEC and PCV of all lambs were determined at weaning (11-12 weeks of age) and at three subsequent times when anthelmintic treatment was administered. Nematode counts of wether lambs were obtained at 30 weeks of age in the first year. The epidemiological patterns of FEC and PCV of each breed group were similar in both years. The Suffolk group consistently showed the highest FEC and the lowest PCV. Conversely, the Native group had the lowest FEC and highest PCV. For the most part, all parameters for the F1 group fell intermediate to the Native and Suffolk groups. Nematode count followed the same pattern. Heterosis analysis showed that FEC, PCV, nematode count and weight gain of the F1 group favored the Native group. These results suggested that crossbreeding Suffolk to Native sheep may be a suitable way to produce lambs with improved resistance to gastrointestinal nematode infection, but production may be compromised.