Obesity has been a major concern in the horse industry for many years, and the recent discovery of leptin and leptin receptors in numerous nonequine species has provided a basis for new approaches to study this problem in equine. The objectives were to: 1) clone a partial sequence ofthe equine leptin and leptin receptor genes so as to enable the design of primers for RT-PCR determination of leptin and leptin receptor gene presence and distribution in tissues, 2) develop a radioimmunoassay to quantify peripheral concentrations of leptin in equine, 3) determine if peripheral concentrations of leptin correlate with body condition scores in equine, and 4) determine if changing body condition scores would influence peripheral concentrations of leptin in equine. In Experiment 1, equine leptin (GenBank accession number AF179275) and the long-form of the equine leptin receptor (GenBank accession number AF139663) genes were partially sequenced. Equine leptin receptor mRNA was detected in liver, lung, testis, ovary, choroid plexus, hypothalamus, and subcutaneous adipose tissues using RT-PCR. In Experiment 2, 71 horses were categorized by gender, age, and body condition score and blood samples were collected. Sera were assayed for leptin using a heterologous leptin radioimmunoassay developed for equine sera. Serum concentrations of leptin increased in horses with body condition score (1 = thin to 9 = fat; r = 0.64; P = 0.0001). Furthermore, serum concentrations of leptin were greater in geldings and stallions than in mares (P = 0.0002), and tended to increase with age of the animal (P = 0.08). In Experiment 3, blood samples, body weights, and body condition scores were collected every 14 d from 18 pony mares assigned to gain or lose weight over a 14-wk interval based on initial body condition score. Although statistical changes (P = 0.001) in body condition scores were achieved, congruent statistical changes in peripheral concentrations of leptin were not observed, likely due to the small range of change that occurred. Nonetheless, serum concentrations of leptin tended to be greater in fat-restricted mares than in thin-supplemented mares (P = 0.09). We conclude that leptin and leptin receptors are present in equine tissues and that peripheral concentrations of leptin reflect a significant influence of fat mass in equine.

Sixty-three Boer crossbred goats were used in 5 separate experiments (Exp. 1 to 5) to evaluate the effects of a commercial probiotic supplement on growth performance (Exp. 1 to 4), diet digestibility (Exp. 5), carcass traits (Exp. 3), and fecal bacterial populations (Exp. 4). Goats were either fed a commercially pelleted concentrate diet and supplemented with a commercial probiotic (PRO) that had shown anecdotal positive effects on goat growth and performance according to local goat producers, or they remained as controls. The dose of PRO used was within the labeled dose for sheep for all studies. For Exp. 1, goat BW and feed intake were measured and G:F was calculated every 7 d for 56 d. For Exp. 2 to 4, BW and feed intake were measured and G:F was calculated every 14 d. The first day of supplementation was considered d 0. Carcass traits were also collected at slaughter on d 57 for Exp. 3, and fecal samples were collected every 14 d for microbial culture for Exp. 4. For Exp. 5, which was a digestibility trial that lasted for 10 d, animals were placed in metabolic pens for collection of feces and orts. Growth performance of goats was not affected by probiotic supplementation, with the exception of performance in Exp. 2, in which ADG and G:F were improved (P < 0.03) in PRO goats compared with control goats on d 56 only (treatment x day interaction; P < 0.05), averaging 0.21 +/- 0.02 kg/d for PRO goats and 0.11 +/- 0.02 kg/d for control goats for ADG and 0.17 +/- 0.02 for PRO goats and 0.10 +/- 0.02 for control goats for G:F. Carcass weights and weights of fabricated cuts (shoulder, loin, leg, rack, shank, and total parts) as well as carcass length, leg circumference, loin eye area, and backfat were not influenced by PRO supplementation. Apparent digestibilities of OM, DM, NDF, ADF, CP, and GE (on a DM basis) were similar for the PRO and control treatments. Fecal culture analysis of Escherichia coli and coliforms, Lactobacillus, and Bifidobacterium populations were not influenced by the PRO treatment. Overall, although the PRO treatment affected goat ADG and G:F in Exp. 2, no PRO treatment effects were noted on growth performance for Exp. 1, 3, and 4. Furthermore, the PRO treatment did not affect diet digestibility, carcass traits, or fecal microbial populations in goats. In conclusion, no consistent benefits were noted from supplementing healthy, growing meat goats with PRO.

Leptin is an adipocyte-derived hormone that suppresses feed intake and increases energy expenditure. Leptin is also involved in regulating body temperature. Thus, the presence of leptin in milk, which can be absorbed through the gut of neonates immediately after birth, may aid in the survival of neonates born in cold weather. Our objectives were to determine the temporal relationship between concentrations of leptin in postpartum ewe blood serum and ewe milk serum, and to determine whether ewe blood and milk serum leptin concentrations were correlated with concentrations of leptin in lamb blood serum in their off-spring. Approximately 1 wk before the expected date of lambing, blood samples, weights, and body condition scores (BCS; 0 to 5 scale) were collected from 27 mixed-parity ewes. Following parturition, ewe blood and milk samples were collected within 2 h of parturition (d 0), 12 h (d 0.5) and 24 h (d 1) after parturition, again on d 5, and weekly thereafter until d 47. Lambs were blood-sampled and weighed within 2 h of parturition (d 0), bled daily until d 5, and bled and weighed weekly thereafter to d 47. Prior to lambing, ewe blood serum leptin was positively correlated with congruent BCS (r2 = 0, 10, P = 0.06), but not weight (P = 0.14). Following parturition, ewe blood serum leptin was positively correlated with BCS, weight, and milk serum leptin (r2 = 0.14, P < 0.0001, r2 = 0.12, P < 0.0001, and r2 = 0.028, P = 0.04). Leptin in milk serum was correlated with ewe weight (r2=0.05, P = 0.007) but not ewe BCS (P = 0.7); however, concentrations of leptin in both ewe blood and milk serum varied with day of lactation (P = 0.0001), being maximal within 24 h of parturition and declining to nadir concentrations by d 5. Leptin in lamb serum was correlated with milk serum leptin, (r2 = -0.05; P = 0.001), but not ewe blood serum leptin (P = 0.5). Concentrations of leptin in lamb serum increased from birth to d 5 and declined thereafter to nadir concentrations by d 19. Elevated concentrations of leptin in milk during the early stages of lactation may provide a mechanism for thermoregulation, satiation, and homeostatic endocrine control in the neonate.

Despite strong economic opportunities and incentives for small ruminant production, their health and productivity are often severely affected by parasitic disease. To combat these effects, most farms administer anthelmintics to their animals at frequent intervals, and without consideration to principles of sustainable integrated parasite management (SIPM). This has led to growing problems caused by the development of drug-resistant populations of gastrointestinal nematodes (GIN) in much of the world, particularly in Haemonchus contortus. The objectives of this research were to characterize levels of anthelmintic resistance on small ruminant farms located in the mid-Atlantic US and to compare the fecal egg count reduction test (FECRT) and larval development assay (LDA) for detecting resistance. To achieve these objectives, the DrenchRite ® LDA was used to evaluate resistance status to benzimidazoles, ivermectin, moxidectin, and levamisole on 20 goat and 14 sheep farms in the Mid-Atlantic US over a 2-year period. A FECRT was also conducted on 14 of the same farms and on 2 additional farms in which the LDA was not completed. For the LDA and coprocultures, fecal samples were collected rectally from a minimum of 10 individual animals, pooled, and express-mailed to the University of Georgia for analysis. For the FECRT, albendazole, ivermectin, moxidectin, and/or levamisole were tested on each farm. Animals were allocated randomly based on FAMACHA © scores to 2-5 treatment groups, which included an untreated control group. The number of treatment groups on a farm depended on the number of qualified animals present. Haemonchus contortus was the most common parasite recovered from fecal cultures; the mean level across all farms was 79%. Results of the LDA indicated resistance to benzimidazoles, ivermectin, moxidectin, and levamisole on 100%, 82%, 47%, and 24% of farms, respectively. Multi-drug resistance to all 3 drug classes was detected for H. contortus on 18% of farms (1 sheep and 5 goat farms). Of the 3 16 farms tested by FECRT, resistance to albendazole was present on 8/10 farms, to ivermectin on 4/4 farms, to moxidectin on 7/9 farms and to levamisole on 2/5 farms tested. Results obtained from the FECRT and the LDA (p = 0.51) were similar. The prevalence of resistance found in this study in the mid-Atlantic region of the US is very similar to that reported in an earlier survey of resistance performed in the Southern US, demonstrating that anthelmintic resistance in GIN is a serious problem on small ruminant farms throughout the Eastern US.

Follicular phase (FOL; Days 17-19; n = 8), luteal phase (LUT; Days 7-9; n = 6), and ovariectomized (OVX; n = 5) crossbred gilts were used (Day 0 = onset of estrus). Blood samples were collected via jugular vein cannula every 15 min for 2 h the day before pituitary collection. Serum was assayed for insulin-like growth factor (IGF)-I, IGF-I binding proteins (IGFBP), LH, estradiol (E2), and progesterone (P4). Anterior pituitary cells were dispersed, cultured, and challenged on Day 4 of culture (Day 0 = day of seeding) with 10(-7) M GnRH or IGF-I (10(-11), 10(-10), 10(-9), 10(-8), or 3 x 10(-8) M) individually or in combination. Serum E2 and P4 concentrations indicated that the animals were in the appropriate stage of the estrous cycle. Mean serum LH concentrations were greater (p < 0.0004) for OVX animals compared to FOL and LUT animals. Mean serum IGF-I concentrations were lower (p < 0.05) for OVX compared to FOL and LUT animals, while serum IGFBP were not different among animals. Basal LH secretion (control) was greater (p < 0.04) in OVX than in FOL or LUT cultures. Relative to control, 10(-11) M IGF-I increased (p < 0.02) LH secretion in FOL, LUT, and OVX cultures, and this response was greater (p < 0.05) in FOL and OVX than in LUT cultures. Only the 10(-11) M IGF-I enhanced basal LH secretion in LUT cultures. In addition, 10(-10) M IGF-I increased (p < 0.05) LH secretion in OVX cultures, and 10(-10) and 10(-9) M IGF-I stimulated (p < 0.05) LH secretion in FOL cultures, whereas basal LH secretion in all groups was unaffected (p > 0.05) by 10(-8) or 3 x 10(-8) M IGF-I. The GnRH-induced LH secretion was unaltered by IGF-I treatment. Results indicate that in vitro IGF-I treatment increased basal LH secretion, with reproductive status modulating LH response to IGF-I.