Adaptability of pregnant Merino ewes to the cold desert climate in Nevada.

Grazing ability is difficult to record in animals under free-ranging conditions without sophisticated methods. Alternatively, grazing ability may be indirectly inferred from changes in BW and production characteristics during the grazing period. The present study investigated the effect of grazing on resource-limited rangelands on BW, wool characteristics, and offspring weaning weights in nine hundred five 5/8, 7/8, and fullblood Merino ewes of 2 to 7 yr of age during a grazing period of approximately 2.5 mo (between January and March). A total of 469 ewes gave birth to a single lamb, 248 to twin lambs, and 188 did not give birth. Body weights were measured and wool samples taken before and after the ewes were allowed to graze freely on the rangelands; absolute change in BW and change in BW as a percentage of initial BW were estimated. On average, grazing on resource-poor rangelands resulted in BW loss, a reduction in fiber diameter and its CV, and increased staple length. Animals with finer wool at the start of the grazing period lost phenotypically (r = -0.07, P < 0.05) and genetically (r = -0.23, P < 0.05) less BW during the grazing period and had a greater probability to carry 1 lamb (or 2) to term (P < 0.05). Animals that lost less BW produced more greasy fleece (r = 0.09, P < 0.01). Body weight change did not significantly influence offspring weaning weights. Change in BW was moderately heritable at h(2) = 0.29; fiber diameter was strongly heritable at h(2) = 0.51. Animals with the least inclusion of Merino genetics lost more BW (P < 0.01) during the grazing period and had a more uniform fiber diameter (P < 0.05) but shorter staples (P < 0.05) and less fleece (P < 0.0001) than animals with a greater level of Merino genetics. Our results indicate that animals with finer wool appeared to be better adapted to the cold Nevada desert. Thus, selection for finer wool may positively influence adaptability to resource-limited cold climate conditions; alternatively, BW change may be selected for directly. Because nutritional deficiencies during pregnancy can have adverse consequences for the offspring, indirect selection for grazing ability would foremost result in healthier ewes that can produce lambs and wool without compromising their welfare.

Effects of prolactin administered to a perfused area of the skin of Angora goats.

It is suspected that prolactin may affect mohair growth; therefore, effects of infusing prolactin on mohair growth were investigated using a skin perfusion technique. Seven Angora wethers (average body weight, 30 +/- 3 kg) were implanted bilaterally with silicon catheters into the superficial branches of the deep circumflex iliac artery and vein. For the first 14 d of the experiment, animals were infused (2.4 mL/h) with prolactin (one side) or control (other side) into the deep circumflex iliac arteries. The infusion rate of prolactin was 2.21 mg/d and was calculated to triple prolactin blood concentration in the perfused region. The area of skin supplied by the deep circumflex iliac artery was approximately 240 cm2. Two weeks after the cessation of infusions, 100-cm2 areas within the perfused regions were shorn to determine mohair growth. Greasy and clean mohair production was decreased (P < 0.05) by prolactin compared with control (3.79 vs 4.62 and 3.02 vs 3.67 g/[100 cm2 x 28 d], respectively). Oxygen satura tion in blood hemoglobin from the deep circumflex iliac veins was greater (P < 0.02) on the side infused with prolactin than on the control side (75.1 vs 68.2%). Higher concentrations of methionine, lysine, valine, isoleucine, and leucine were observed in blood of the deep circumflex iliac vein on the side infused with prolactin vs that infused with control (P < 0.05). In conclusion, direct skin infusion with prolactin decreased mohair fiber synthesis by the skin and may have concomitantly lessened oxygen consumption. Thus, effects of increasing prolactin concentration approximately two-fold in the skin on mohair fiber growth may not be limited to simple competition for nutrients between skin and other tissues such as the mammary gland.

Effects of small peptides or amino acids infused to a perfused area of the skin of Angora goats on mohair growth.

The effect of infusing dipeptides or their amino acids on mohair growth of Angora goats was investigated using a skin perfusion technique. Seven Angora wethers (average BW 24 +/- 2.5 kg) were implanted bilaterally with silicon catheters into the superficial branches of the deep circumflex iliac artery and vein and carotid artery. The experiment consisted of three 28-d phases. In the first 14 d of Phases 1 and 3, saline was infused into deep circumflex iliac arteries supplying skin and in Phase 2 a mixture of dipeptides (methionine-leucine [Met-Leu], lysine-leucine [Lys-Leu]) was infused into the artery on one side, and free amino acids were administered on the other side. Infusion rates of peptides were 0.85 mg/h Met-Leu and 0.85 mg/h Lys-Leu in 2.4 mL saline. Infusion rates of amino acids were 0.474 mg/h Lys, 0.483 mg/h Met, and 0.743 mg/h Leu in 2.4 mL saline. A 100-cm2 area within the perfused region was used to determine mohair growth. Two weeks after the cessation of infusions, perfused areas were shorn. Clean mohair production from the dipeptide- and amino acids-perfused regions were similar (4.21 vs 4.35 g/[100 cm2 +/- 28 d], respectively; P > 0.05). However, clean mohair production during dipeptides and amino acids infusions was greater (P < 0.01) than that observed during saline infusions (3.63 g/[100 cm2 +/- 28 d]). There were no significant differences between dipeptides and free amino acids in concentrations of various hormones and metabolites in blood from deep circumflex iliac veins (P > 0.05). In conclusion, the studied small dipeptides and amino acids similarly increased mohair fiber growth, presumably through supplying limiting amino acids directly to the fiber follicle.

Production performance, repeatability and heritability estimates for live weight, fleece weight and fiber characteristics of alpacas in New Zealand.

The production performance, repeatability and heritability estimates for live weight, fleece weight and fiber characteristics of alpacas farmed in the South Island of New Zealand are reported. Male alpacas produced heavier fleeces (p<0.001) than females, but with relatively similar fiber diameter. Mean (S.E.) shearing weight, greasy fleece weight (GFW), clean fleece weight (CFW), yield, staple length (SL), resistance to compression (RtC) and fiber diameter (FD) in adults were 68.0kg (1.0), 2.16kg (0.06), 2.03kg (0.06), 93.6% (0.4), 9.9cm (0.2), 5.3kPa (0.1) and 31.9µm (0.5), respectively. These means in tuis were 68.1kg (1.9), 3.02kg (0.20), 2.94kg (0.27), 92.2% (0.4), 12.2cm (0.3), 4.8kPa (0.1) and 30.5µm (0.9), respectively. The corresponding measurements in crias were 40.5kg (1.1), 1.97kg (0.07), 1.84kg (0.07), 93.4% (0.3), 12.6cm (0.2), 4.6kPa (0.1) and 26.4µm (0.4), respectively. The birth weight (BWT) was 8.4kg (0.1) and SS was 28.4 N/ktex (1.9) in crias. The seasonal variation of fiber growth and fiber diameter was small to moderate, with lowest values in the winter. Mid-side fleece site FD was highly correlated with other main sites sampled and shown to be appropriate as a standard sampling site. The phenotypic correlation between CFW and FD was 0.40 (p<0.001) and for fleece weight and shearing live weight was 0.47 in adult alpacas (p<0.001). Correlation coefficients for GFW and CFW with FD and SL were highly positive (GFW with FD and SL: 0.32-0.45, 0.39-0.54; CFW with FD and SL: 0.37-0.46, 0.40-0.53) in both tui and cria fleeces. The heritabilities for BWT, summer weight, spring weight, GFW and CFW, yield, SL, RtC and FD were estimated as 0.63, 0.41, 0.99, 0.63, 0.68, 0.67, 0.57, 0.16, 0.69 and 0.73. Production performance and heritability estimates for these traits were markedly higher than that previously reported in South American camelids.

Mapping the Horns (Ho) locus in sheep: a further locus controlling horn development in domestic animals.

The presence or absence of horns in Merino sheep is under the genetic control of the autosomal Horns (Ho) locus. Sheep chromosome OOV1 is a candidate region for the Ho locus because it shows conserved synteny with cattle chromosome BBO1 where the cattle polled locus has been located. We demonstrate that the Ho locus in sheep is excluded from sheep chromosome OOV1 and we identified linkage between the Ho locus and markers from sheep chromosome OOV10. These data suggest that there are at least two loci affecting the presence or absence of horns in sheep and cattle. The orthologous regions to OOV10 are likely to be on cattle, human, and mouse chromosomes BBO12, HSA13, and MMU14.