Effects of mimosine and 2,3-dihydroxypyridine on fiber shedding in Angora goats.

The effects of intravenous infusion of mimosine or 2,3-dihydroxypyridine (2,3-DHP) and the effects of oral dose level of mimosine on fiber shedding in Angora goats were determined. In one experiment, 20 mature Angora wethers (36+/-1.9 kg BW) were infused for 2 d with 79, 102, or 135 mg/(kg BW.d) of mimosine, 90 mg/(kg BW.d) of 2,3-DHP, or saline. At 7 d after infusion began, fiber shedding was observed in all goats receiving mimosine but not in any goats infused with 2,3-DHP or saline. Fiber shedding varied among goats; in some goats, fiber shedding was complete and occurred without hand-plucking, whereas in others fiber was retained by nonshed fibers but could be removed by hand-plucking. Nonshed fibers were larger in diameter and more likely to be medullated (P < .05) compared with hand-plucked fibers. Mean plasma mimosine concentration at 24 and 48 h after infusion began was 79 and 98 micromol/L (P < .05), respectively, and greater (P < .05) for mimosine infused at 135 than at 102 mg/(kg BW.d) (89, 68, and 108 micromol/L for mimosine infused at 79, 102, and 135 mg/[kg BW.d], respectively; SE 9.5). In another experiment, oral dosing of eight Angora bucks (23+/-.5 kg BW) with 400 or 600 mg/kg BW of mimosine rapidly increased plasma mimosine concentration, which reached approximately 100 and 160 micromol/L at 5 h after dosing; however, periods of time during which plasma mimosine concentrations were comparable to those in the first experiment were considerably shorter. Oral mimosine dosing did not induce fiber shedding in 7 d. After 31 d, fiber was retained by nonshed fibers but could be removed by hand-plucking or could only be partially removed with difficulty by hand-plucking. There were no toxic effects of mimosine or 2,3-DHP administration; only minor, short-term inhibitions of feed intake by mimosine were noted in some goats. In conclusion, mimosine holds promise as a safe means to remove fiber of Angora goats; further research is necessary to characterize the seasonality of follicle activity and to develop convenient means of mimosine delivery.     

Effects of bovine somatotropin and thyroid hormone status on hormone levels, body weight gain, and mohair fiber growth of Angora goats.

Forty-eight Angora goats (24 wethers and 24 doelings; 5 mo old; 16 +/- 0.5 kg initial BW) were used in an experiment with a 2 x 3 factorial treatment arrangement (n = 8) to evaluate effects of recombinant bovine somatotropin (bST) administration and thyroid hormone status (euthyroid, hypothyroid, and hyperthyroid) on hormone levels, ADG, and mohair fiber growth. The bST was a slow-release zinc-based suspension, with sustained delivery (100 microg/[kg BW x d]) over a 14-d period. Hyperthyroidism was maintained by daily treatment with thyroxine (T4; 150 microg/[kg BW x d]), and hypothyroidism was achieved by feeding 6 mg/(kg BW x d) of propylthiouracil. The experiment was conducted in July to September and consisted of a 2-wk pretreatment period and 8 wk of bST treatment. Goats were given ad libitum access to a diet with 15% CP and 2.54 Mcal/ kg ME (DM basis). Concentrations of T4 and T3 were greatest (P < 0.01) among treatments for hyperthyroid-bST and hyperthyroid-control (T4: 38.6 and 38.0 microg/dL; T3: 406 and 385 ng/dL, respectively); similar among euthyroid-control, euthyroid-bST, and hypothyroid-bST (T4: 11.1, 11.5, and 9.8 microg/dL, respectively; T3: 232, 252, and 226 ng/dL, respectively); and lowest (P < 0.01) for hypothyroid-control (T4: 5.1 microg/dL; T3: 144 ng/dL). Plasma concentration of insulin-like growth factor-I was greatest (P < 0.01) for euthyroid-bST (596 ng/mL) and hypothyroid-bST (618 ng/mL); however, concentration for hyperthyroid-bST was similar to those for euthyroid-control, hypothyroid-control, and hyperthyroid-control (188, 178, 187, and 191 ng/mL, respectively). Dry matter intake was greatest (P < 0.05) for euthyroid-bST (794 g/d), similar among hypothyroid treatments (693 and 703 g/d for control and bST, respectively) and euthyroid-control (681 g/d), and lowest for hyperthyroid groups (554 and 518 g/d for control and bST, respectively); ADG for hyperthyroid goats (11 g/d) was lower than with hypothyroidism and euthyroidism (72 and 73 g/d, respectively); and mohair fiber growth was greater (P < 0.01) for hyperthyroidism (0.133 g/[100 cm2 x d]) than for hypothyroid and euthyroid goats (0.102 and 0.104 g/[100 cm2 x d], respectively). Hyperthyroidism also increased mohair length growth rate by 15% and decreased fiber diameter by 7.8% (P < 0.01). These results demonstrate interactions between growth hormone administration and thyroid hormone status, although these influences had limited effects on ADG and mohair fiber growth.     

Digestibility and feeding value of pearl millet as influenced by the brown-midrib, low-lignin trait

Our objectives were to determine the intake and digestibility of pearl millet as influenced by the brown-midrib (BMR), low-lignin trait and to determine the relative acceptability of BMR pearl millet in relation to its normal counterpart. Two field replicates of brown-midrib pearl millet and its normal counterpart were harvested as hay at the boot to heading stage twice during the growing season (2 genotypes x 2 cuttings x 2 field replicates). Twenty-four wethers had ad libitum access to a total forage diet (pearl millet forage), water and trace mineralized salt. The experimental period was 21 d (14 d for adjustment and 7 d for sample collection). Lignin was 23% lower (P less than or equal to .01) and in vitro DM digestibility (IVDMD) was 4% higher (P less than or equal to .01) in BMR vs normal genotype forages. Wethers preferred first-cutting millet to second-cutting millet, as evidenced by 62% higher (P less than or equal to .01) DMI for first-cutting forages. Dry matter intake of second-cutting forages was higher (P less than or equal to .10) for BMR pearl millet forage than for normal pearl millet (2.0 vs 1.5% of BW), but first-cutting forages were similar in DMI (2.9% of BW). In an acceptability trial of pearl millet regrowth (4 wk), grazing lambs with access to both genotypes displayed a marked preference (P less than .01) for the BMR genotype, spending an average of 2.6 min on plots containing the brown-midrib pearl millet for every minute spent on the normal genotype.(ABSTRACT TRUNCATED AT 250 WORDS)     

Heat energy for growing goats and sheep grazing different pastures in the summer.

Angora goat, Spanish goat, and Suffolk x Rambouillet sheep wethers (20 of each type; 30.4+/-.57, 31.3+/-.93, and 32.4+/-1.08 kg BW for Angora goats, Spanish goats, and sheep, respectively) were used to investigate influences of animal type and two grass-based pasture treatments on heat energy during summer grazing (mid-August through September in Oklahoma). The improved pasture treatment consisted of .7-ha paddocks primarily of Old World bluestem and johnsongrass, whereas the native pasture treatment entailed 10.8-ha paddocks dominated by big and little bluestems and indiangrass. Grasses were 95 to 100% of diets for the improved pasture treatment and 71 to 95% for the native pasture treatment; forbs were 2 to 25%, and shrubs were less than 4% of diets for the native pasture treatment. Metabolizable energy intake was similar (P > . 10) between pasture treatments but differed (P <.01) among animal types: 79, 99, and 113 kcal/(kg(.75) BW.d) for Angora goats, Spanish goats, and sheep, respectively; SE 7.1. Heat energy estimated via CO2 entry rate was affected by pasture treatment ( P = .08) and animal type (P < .001): improved pasture treatment 109, 132, and 151 kcal/(kg(.75) BW.d); native pasture treatment 126, 138, and 163 kcal/(kg(.75) BW.d) for Angora goats, Spanish goats, and sheep, respectively. Likewise, daylight grazing time was greater (P = .04) for the native than for the improved pasture treatment and differed (P < .01) among animal types: improved pasture treatment 5.3, 4.7, and 6.7 h; native pasture treatment 6.0, 5.7, and 8.1 h for Angora goats, Spanish goats, and sheep, respectively. In conclusion, heat energy during summer grazing of grass-based paddocks was less for goats than for sheep, and animal type can affect the increase in heat energy as energy intake and grazing time increase.     

The induction of cashmere shedding via cyclophosphamide injection

The aim of this study was to investigate the effects of cyclophosphamide (CPA) on cashmere shedding in cashmere goats. Thirty‐two castrated Liaoning cashmere goats were randomly allotted to four groups, with eight replicates in each group. The four groups were injected intravenously with CPA doses of 0, 15, 20 and 25   mg/kg body weight, respectively. Feed intake, body weight, body temperature, and sphygmus were recorded and the erythrocyte count, leukocyte count, hemoglobin content, and cashmere yield and length were determined. CPA has no significant effect on feed intake, body weight, body temperature, or sphygmus of cashmere goats. It was found that CPA significantly decreased the erythrocyte count and hemoglobin content in cashmere goats on the days immediately following injection, but the effects on erythrocytes diminished within 6 days, with hemoglobin content returning to normal within 10 days. Cashmere fiber began to shed on about day 10 after injection with CPA. CPA had no significant effect on cashmere length but significantly increased cashmere yield. The results indicate that CPA can induce cashmere shedding and achieve the purpose of concentrated defleecing. A dose of 20 mg/kg body weight is preferable for hair removal and regrowth in cashmere goats.     

Effect of intraperitoneal administration of lysine and methionine on mohair yield and quality in Angora goats.

Eight mature Angora wethers (average BW 47.2 kg) were used in a 4 x 4 replicated Latin square design to evaluate responses to intraperitoneal (IP) administration of amino acids. The IP treatments consisted of saline (Control), methionine 1 g/d (Met), lysine 2 g/d (Lys), and methionine + lysine (Met + Lys). The amino acids dissolved in Control were infused continuously for the first 14 d of each 28-d period using peristaltic infusion pumps. Average d-28 grease and clean mohair yields (grams/100 square centimeters), and fiber diameter (micrometers) and length (centimeters) measurements during Control administration were 8.8, 7.6, 40, and 2.3, respectively. Mean clean mohair yield and fiber diameter increased by 5.3% (P less than .039) and 2.5% (P less than .067), respectively, with Met administration but were decreased by 9.2% (P less than .033) and 3.8% (P less than .001), respectively, by Lys administration; however, mean fiber length was increased (P less than .014) 21.7% by Lys infusion. The goats did not exhibit increased grease (P greater than .939) and clean (P greater than .477) mohair yields and fiber diameter (P greater than .619) when treated with Met+Lys. A N balance trial was conducted during d 10 through 14 of each period. Total retained N (grams per day) during Control administration was 18.4 and 24% greater than Met (P greater than .281) and Lys (P less than .061), respectively. When expressed as a proportion of N intake, retained N was lowest (P less than .127) in the Lys infusion group. Jugular blood ammonia N and plasma glucose and total protein concentrations were not affected (P greater than .10) by treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of tryptophan supplementation on cashmere fiber characteristics, serum tryptophan, and related hormone concentrations in cashmere goats

This study was designed to investigate the effects of tryptophan (Trp) supplementation on cashmere fiber characteristics and on serum Trp, melatonin (MEL), prolactin (PRL), insulin-like growth factor 1 (IGF-1), triiodothyronine (T(3)), and thyroxine (T(4)) concentrations in cashmere goats during the cashmere fast-growth period. Thirty-six Liaoning cashmere wether goats were stratified on the basis of body weight (28 ± 0.8 kg) and assigned randomly to 1 of the following 4 rumen-protected Trp treatments: 0, 2.0, 4.0, and 6.0 g per goat per day. The experimental period lasted 137 d. Blood samples were collected monthly during the daytime (8:00 AM) and at night (8:00 PM). Tryptophan supplementation improved cashmere growth rates, cashmere weight, and body weight (P = 0.001) and increased serum Trp levels, nighttime MEL concentrations, IGF-1, and T(3) and T(4) concentrations (P < 0.05). Across the treatments and sampling months, a highly positive correlation between cashmere growth rate and nighttime serum MEL concentrations was observed (r = 0.879, P = 0.001). A moderately negative correlation between cashmere growth rates and serum PRL concentrations during the day and at night (r(day) = -0.645, P = 0.007; r(night) = -0.583, P = 0.018) was observed. A moderately positive correlation between the cashmere growth rate and the daytime serum IGF-1 concentration (r = 0.536, P = 0.032) was observed, and no correlation was found between the cashmere growth rate and the other serum hormone concentrations. These data indicate that changes in serum concentrations of MEL, IGF-1, and PRL are related to cashmere growth in Liaoning cashmere goats during the cashmere fast-growth period. Under the experimental conditions of the current trial, we suggest that Trp may promote cashmere growth by increasing daytime IGF-1 and nighttime MEL secretion.     

限饲对辽宁绒山羊生产性能及消化代谢的影响

本试验旨在研究限饲对辽宁绒山羊生产性能及消化代谢的影响。将20只1周岁、体重(22.29±1.05)kg辽宁绒山羊母羊随机分为4个采食水平组,即干物质为基础分别为自由采食100%(AL),以及自由采食组采食量的90%(IR90)、80%(IR80)和70%(IR70)。结果表明:不同限饲水平对绒山羊的体重和日增重有显著影响(P<0.05),日增重随饲喂水平的下降而显著下降,分别为32.20、17.40、10.80 g/d和-8.20 g/d;饲料增重比在AL和IR90两组间无显著差异(P>0.05),其余各组间差异显著(P<0.05)。不同限饲水平对绒山羊的营养物质表观消化率无显著性影响(P>0.05)。不同限饲水平显著影响进食氮、粪氮排出和沉积氮(P<0.05);随限饲水平的下降,沉积氮分别为3.05、2.62、1.87 g/d和1.18 g/d;限饲水平对尿氮的排出和氮的利用率影响差异不显著(P>0.05)。在本试验条件下,限饲显著影响绒山羊的体重、日增重和氮沉积,辽宁绒山羊育成母羊粗蛋白的维持需要为46.16 g/d,高于NRC(1981)的相同生长阶段山羊蛋白质维持需要量推荐值。     

Effects of methionine hydroxy analog on voluntary intake, digestibility, nitrogen balance, and chewing behavior in sheep fed grass silage

Voluntary intake, digestibility, N balance, and chewing behavior of six 6-mo-old (young) and six 30-mo-old (mature) Texel wethers (32.6 and 83.1 kg average BW) given ad libitum access to grass silage and 100 g of top-dressed soybean meal with or without 5 g of methionine hydroxy analog (MHA) in the acid form were examined according to a two-period crossover design. Supplementation level of MHA in the acid form corresponded to .32 and .16 g of MHA/kg BW.75, respectively, in young and mature wethers. There was no effect (P greater than .10) of MHA on mean voluntary DMI. Methionine hydroxy analog supplementation increased (P less than .02) digestibility of DM, OM, and CP by young wethers but not (P greater than .18) by mature wethers. The MHA decreased eating time (P less than .03) in both young and mature wethers and intake level (P = .01) in young wethers during the first 1.5 h of access to grass silage. With MHA, both age groups increased (P less than .05) the daily number of meals and decreased (P less than .02) the mean duration of each meal. There was no effect (P greater than .06) of MHA on daily and unitary eating, ruminating, and masticating times; however, mean duration of consecutive rumination bolus cycles was longer (7.2%; P = .01) in young wethers. Young vs mature sheep ate more (53.4 vs 39.3 g of DM/[d.kg BW.75]; P less than .001) and had shorter unitary mastication times (P = .001). Results suggest that, depending on its relative level of supplementation, MHA in the acid form could act through both palatability and effects on ruminal metabolism.     

绒山羊皮肤毛囊兴盛前期组织形态、chi-miR-107-3p与RHBDF2基因表达分析

为了探究chi-miR-107-3p和菱形家族蛋白2（rhomboid family member 2,RHBDF2）基因在不同品种（系）和光控增绒绒山羊兴盛前期（5~7月份）皮肤毛囊重建时的表达差异,本试验在7月份采集内蒙古阿拉善型绒山羊、敏盖绒山羊和光控增绒技术处理的阿尔巴斯型绒山羊体侧皮肤毛囊组织,采用组织切片技术对组织形态比较分析,实时荧光定量PCR法检测chi-miR-107-3p和RHBDF2基因的表达量。结果显示,在皮肤毛囊兴盛前期,阿拉善型绒山羊次级毛囊正处于重建阶段,敏盖绒山羊和阿尔巴斯型绒山羊（光控增绒）次级毛囊重建已基本完成;在阿拉善型绒山羊皮肤组织中chi-miR-107-3p表达量极显著高于敏盖绒山羊和阿尔巴斯型绒山羊（光控增绒）（P<0.01）,而RHBDF2基因表达量极显著低于其他两品种（系）（P<0.01）,且RHBDF2基因表达量在敏盖绒山羊皮肤组织中显著低于阿尔巴斯型绒山羊（P<0.05）。不同品种（系）和光控增绒绒山羊皮肤毛囊兴盛前期组织显微结构与chi-miR-107-3p、RHBDF2基因在皮肤组织中的表达差异分析结果相一致,次级毛囊重建初期chi-miR-107-3p表达量较高,而RHBDF2基因表达量极低,随着次级毛囊重建完成,chi-miR-107-3p表达量明显降低,RHBDF2基因表达量逐渐增高,且在不同品种（系）内蒙古绒山羊绒毛生长发育过程中的表达机制基本相同。因此,chi-miR-107-3p和RHBDF2基因是绒山羊皮肤毛囊生长发育的重要调控因子。     

Effect of sex and rearing system on the quality and mineral content of fiber from raeini cashmere goats

The aim of this study was to compare the quality characteristics and mineral content of the fiber from male and female cashmere goats raised under different management systems. Male and female Raeini cashmere goats (<1.5 years of age, n = 48) were selected from flocks raised at a government breeding station or raised commercially under either rural or nomadic conditions. The staple length, cashmere fiber diameter, coefficient of variation for fiber diameter, percentage of cashmere in a fleece, percentage of guard hair in a fleece and cashmere tenacity averaged 4.6 ±0.1 cm, 18.0 ±0.1 m, 20.9 ± 0.4%, 66.1 ± 1.5%, 33.8 ± 1.5% and 1.8 ± 0.2 gf/tex, respectively. The sulfur, copper and zinc content of the cashmere averaged 2.8 ± 0.1%, 0.00065 ± 0.00002% and 0.01276 ± 0.00025%, respectively. Rearing method significantly affected staple length, coefficient of variation of fiber diameter, cashmere tenacity and copper content. Males had a higher coefficient of variation of fiber diameter and cashmere tenacity than females (P < 0.05).     

Growth and slaughter traits of Boer x Spanish, Boer x Angora, and Spanish goats consuming a concentrate-based diet.

The number of Boer crossbred meat goats has been increasing rapidly, although how their growth and slaughter traits compare with those of Spanish goats and influences of maternal genotype have not been thoroughly evaluated. This information would be useful to achieve optimal meat goat production systems and yield of goat products desired by consumers. Therefore, postweaning growth (9 to 24 wk of age) and slaughter traits (212 +/- 5.0 d of age) of Boer x Spanish, Spanish, and Boer x Angora wethers (n = 16, 18, and 18 for growth measures, respectively, and n = 6 per genotype for slaughter traits) consuming a concentrate-based diet were compared. Over the 16-wk performance period, ADG, DMI, and ADG:DMI were greater (P < 0.05) for Boer crossbreds than for Spanish goats (ADG: 154, 117, and 161 g; DMI: 646, 522, and 683 g/d; ADG:DMI: 263, 235, and 261 g/kg for Boer x Spanish, Spanish, and Boer x Angora, respectively). Dressing percentage (46.3, 47.3, and 47.0% of BW; SE = 1.21) and quality grade score (11.17, 9.67, and 11.17 for Boer x Spanish, Spanish, and Boer x Angora, respectively; SE = 0.66 [12 = Choice+; 11 = Choice; 10 = Choice-; 9 = Good+]) were similar among genotypes. Weights of some noncarcass components were greater for Boer crossbreds than for Spanish goats, but relative to empty BW, noncarcass component weights were similar among genotypes. Concentrations of moisture, ash, fat, and protein in carcass and noncarcass components did not differ among genotypes. Contributions to the carcass of different primal cuts were similar among genotypes, and there were few differences in concentrations of separated lean, bone, and fat in primal cuts. In conclusion, when consuming a concentrate-based diet, early postweaning growth rate was similar between Boer x Spanish and Boer x Angora wethers and greater for Boer crossbreds than for Spanish wethers. Slaughter traits were primarily related to differences in final BW.     

Influences of gender, time of castration, genotype, birthtype and feeding regimen on lamb longissimus fiber type proportions

Two trials examined genetic and environmental influences on muscle fiber type proportions. Trial 1 compared Polypay and Coopworth x Polypay male lambs either left intact or castrated early, mid or late in growth. Trial 2 compared Hampshire-sired lambs (females, early castrate wethers and late castrate wethers) from Suffolk x Coopworth dams and whiteface x Coopworth dams. Half the lambs in each trial were raised from weaning to 52 kg slaughter weight in drylot; the other half were reared to 41 kg on pasture before being finished in drylot. Analysis of longissimus tissue samples revealed no significant differences among rams, wethers and ewes in proportions of muscle fiber types. Early castration increased the proportion of alpha red fibers in Trial 1 (P less than .01) but not in Trial 2. Polypay lambs had a higher proportion of beta red fibers (P less than .05) than the Coopworth x Polypay lambs, but no differences were seen between the genotypes of Trial 2. Single-born lambs in Trial 1 had a 6% higher proportion of alpha white fibers (P less than .05) than twin-born lambs; however, this difference was not detected in Trial 2. Drylot lambs had a higher proportion of beta red fibers than pasture-reared lambs, the difference being 5% (P less than .01) in Trial 2. Muscle fiber type proportions were not found to be related to growth rate and carcass fatness, and no evidence of differential fiber transformation was found in this trial.     

Effects of melatonin implantation on cashmere yield,fibre characteristics,duration of cashmere growth as well as growth and reproductive performance of Inner Mongolian cashmere goats

Background

Exogenous melatonin could induce cashmere growth. However, induced growth of cashmere fleece by melatonin implants cannot be combined with the typical growth, resulting in earlier shedding followed by another cycle of cashmere growth. To address this issue, we examine the effects on the cashmere yield, fibre characteristics, and the growth and reproductive performance of cashmere goats of planned administration of melatonin.

Methods

Eighteen half-sib, female goats were assigned to two treatments (n = 9) including a control and a treatment where melatonin (2 mg/kg BW) was implanted at the end of April and end of June. Cashmere growth and shedding were observed for approximately 1 year following implantation. Fibre samples were collected monthly to determine cumulative cashmere length. Initiation and cessation dates for cashmere growth as well as the rate of cashmere growth were calculated. Cashmere yield, weight gain of dam, kidding date, litter size, and birth weight were also recorded.

Results

Melatonin implantation increased cashmere yield by 34.5 % (control 553.7 g vs. melatonin 745.0 g; P < 0.01), cashmere length by 21.3 % (control 95.2 mm vs. melatonin 115.4 mm; P < 0.01), and decreased fibre diameter by 4.4 % (control 14.6 μm vs. melatonin 14.0 μm; P < 0.03). In melatonin-treated goats, the average initiation date was earlier than in control goats (May 18, 2013 vs. July 2, 2013; P < 0.01) but there was a similar cessation date (March 22, 2014 vs. March 27, 2014). Consequently, the duration of cashmere growth was longer in melatonin-treated goats than in control goats (307 vs.270 days; P < 0.01). The final BW, average daily gain, kidding date, litter size, and birth weight were not influenced by melatonin implantation.

Conclusions

These data indicate that melatonin implantation (2 mg/kg BW) on two occasions (late April and June) increased cashmere yield by combining the induced growth of cashmere fleece with the typical growth and decreased the fibre diameter without changing dam growth rate or reproductive performance.     

Effects of supplemental protein type on intake, nitrogen balance, and site, and extent of digestion in whiteface wethers consuming low-quality grass hay

Two experiments were conducted to determine the effects of supplementing ruminally degradable intake protein (DIP) or ruminally undegradable intake protein (UIP) on N balance (Exp. 1; n = 6 wethers; initial BW = 48.7 +/- 4.6 kg) and site and extent of digestion (Exp. 2; n = 5 wethers; initial BW = 36.9 +/- 3.1 kg) in whiteface wethers consuming (as-fed basis) 69% blue grama and 31% love grass hay (mixture = 7.5% CP, 73.0% NDF, 36.0% ADF [DM basis]). Treatments were 1) no supplement (Control), 2) a supplement (219 g/d, as-fed basis) low in UIP (70 g/d of CP; 24.8 g/d of UIP), and 3) a supplement (219 g/d, as-fed basis) high in UIP (70 g/d of CP; 37.1 g/d of UIP). Both experiments were replicated 3 x 3 Latin square designs, with identical feeding and supplementation. Wethers had ad libitum access to the forage mixture and fresh water, and received supplement once daily. In Exp.1, forage intake (percentage of BW) was greatest (P = 0.04) for control, but total DMI (g/d) was greatest (P = 0.05) for lambs consuming supplement. Apparent total-tract OM digestibility was numerically greater (P = 0.11) for supplemented wethers than for controls, whereas total-tract ADF digestibility tended (P = 0.08) to be greater for control wethers. Lambs fed supplements consumed and retained more (P < or = 0.01) N (% of N intake) compared with controls, but no difference (P = 0.22) was observed between low and high UIP treatments. Similar to Exp. 1, forage intake (percentage of BW) tended (P = 0.06) to be greater for control than for supplemented wethers in Exp. 2. Ruminal NDF digestibility was 16.3% greater (P = 0.02) for supplemented wethers than for controls. Postruminal NDF and N digestibilities were greatest (P < or = 0.03) for controls, but apparent OM digestibility did not differ among treatments at all sites. Duodenal N flow was greatest (P = 0.05) for high UIP and least for control wethers. Nonmicrobial N flow was greater (P = 0.02) for high UIP compared with low UIP or controls. Control wethers had greater (P = 0.05) microbial efficiency. Ruminal ammonia concentration tended (P = 0.08) to be greatest for wethers fed low UIP and least for controls, with high-UIP wethers having intermediate ammonia concentrations. Results from these experiments suggest that in lambs fed low-quality forage there was no difference in apparent total-tract digestion or N balance (percentage of N intake) between lambs fed supplements that had the same CP but differed in the proportion of UIP and DIP; however, supplementing protein (regardless of UIP:DIP ratio) to wethers consuming low-quality forage increased N balance.     

Effects of bovine somatotropin and ruminally undegraded protein on feed intake, live weight gain, and mohair production by yearling Angora wethers.

Yearling Angora wethers (n = 24; 24+/-1.0 kg BW) were used in an experiment with a 2 x 2 factorial arrangement of treatments to investigate effects of bovine somatotropin (bST) treatment and dietary level of ruminally undegraded protein on DMI, ADG, and mohair production. Untreated casein (UC) or casein treated with formaldehyde (TC) was included at 7% DM of a diet containing 11% CP and 46% concentrate. A slow-release bST form was administered weekly to deliver 0 (Control) or 100 microg/ (kg BW.d) of bST. Plasma concentrations of bST and IGF-I were increased (P < .05) during the 7-d period following bST injection. Ruminal fluid ammonia N concentration was lower (P < .01) for TC than for UC before feeding (6.6 vs 7.5 mg/dL) and 4 h later (8.2 vs 12.2 mg/dL), and total VFA concentration was lower (P < .01) for TC than for UC. Treatment with bST decreased (P = .08) DMI with UC (1.15 vs .91 kg/d) and increased (P = .08) DMI with TC (.95 vs 1.06 kg/d). Formaldehyde treatment of casein increased ADG (65, 74, 55, and 91 g/d; P = .03) and clean fleece production (P < .01; 14.1, 17.3, 15.0, and 18.4 g/d for UC-Control, TC-Control, UC-bST, and TC-bST, respectively), with no effect of bST during the 8-wk period of treatment or for the 8 wk thereafter (P > .10). In conclusion, with yearling Angora wethers, bST does not seem useful to enhance mohair production and may not alter effects of dietary level of ruminally undegradable protein on mohair production.     

埋植外源褪黑激素对不同年龄内蒙古绒山羊产绒性能的影响

为研究非长绒期埋植外源褪黑激素对不同年龄内蒙古绒山羊产绒性能的影响,本试验选择2～6岁能繁母羊150只,每个年龄段根据产绒量和体重将母羊随机分为对照组和试验组,试验组于2014年4月30日和6月30日埋植2 mg/kg BW褪黑激素于耳部皮下。自埋植开始至试验结束(2015年4月底抓绒),逐月观察山羊绒生长情况,并于抓绒时采集绒样,分析埋植对山羊绒生长的影响。结果表明:与对照组相比,试验组所有年龄段山羊绒产量和绒长度均显著提高,绒细度显著降低(P<0.05),其中5岁埋植组山羊的产绒量提高幅度和细度下降幅度最大,分别达到28.75%、4.94%,6岁埋植组山羊绒长度增加幅度最大,为29.27%。综上,不同年龄内蒙古绒山羊埋植外源褪黑激素均有促进山羊绒生长和提高产量作用,但不同年龄绒山羊增产效果不一致,并且褪黑激素对于提高内蒙古绒山羊后期的生产力作用更大。     

Effect of feeding fat or intrajugular infusion of glucagon-like peptide-1 and cholecystokinin on dry matter intake, digestibility, and digesta rate of passage in growing wethers

A cause and effect relationship between glucagon-like peptide 1 (7, 36) amide (GLP-1) and cholecystokinin (CCK) and DMI regulation has not been established in ruminants. Three randomized complete block experiments were conducted to determine the effect of feeding fat or infusing GLP-1 or CCK intravenously on DMI, nutrient digestibility, and Cr rate of passage (using Cr(2)O(3) as a marker) in wethers. A total of 18 Targhee × Hampshire wethers (36.5 ± 2.5 kg of BW) were used, and each experiment consisted of four 21-d periods (14 d for adaptation and 7 d for infusion and sampling). Wethers allotted to the control treatments served as the controls for all 3 experiments; experiments were performed simultaneously. The basal diet was 60% concentrate and 40% forage. In Exp. 1, treatments were the control (0% added fat) and addition of 4 or 6% Ca salts of palm oil fatty acids (DM basis). Treatments in Exp. 2 and 3 were the control and 3 jugular vein infusion dosages of GLP-1 (0.052, 0.103, or 0.155 μg?kg of BW(-1)?d(-1)) or CCK (0.069, 0.138, or 0.207 μg?kg of BW(-1)?d(-1)), respectively. Increases in plasma GLP-1 and CCK concentrations during hormone infusions were comparable with increases observed when increasing amounts of fat were fed. Feeding fat and infusion of GLP-1 tended (linear, P = 0.12; quadratic, P = 0.13) to decrease DMI. Infusion of CCK did not affect (P > 0.21) DMI. Retention time of Cr in the total gastrointestinal tract decreased (linear, P < 0.01) when fat was fed, but was not affected by GLP-1 or CCK infusion. In conclusion, jugular vein infusion produced similar plasma CCK and GLP-1 concentrations as observed when fat was fed. The effects of feeding fat on DMI may be partially regulated by plasma concentration of GLP-1, but are not likely due solely to changes in a single hormone concentration.     

Ruminal fermentation and degradation patterns, protozoa population and urinary purine derivatives excretion in goats and wethers fed diets based on olive leaves

Olives leaves, accrued during the processing of olive harvests for oil extraction, are poor in N, rich in crude fat and ADF (1.19, 8.03 and 28.2 g/100 g of DM, respectively), and relatively low in condensed tannins (11.1 mg/g of DM). Three experiments were conducted in a 2 x 3 (two animal species: goats vs. wethers; and three experimental diets: olive leaves without or with polyethylene glycol supply and olive leaves supplemented with barley and faba beans) factorial design to evaluate ruminal degradation and passage kinetics (Exp. 1), fermentation pattern and protozoa population (Exp. 2), and urinary purine derivatives excretion (Exp. 3). Polyethylene glycol was supplied to evaluate the effects of condensed tannins contained in olive leaves. Ruminal degradability of CP was low in both goats and wethers, although goats showed higher (P < 0.05) values than wethers. Supplementation of olive leaves with barley and faba beans increased (P < 0.001) ruminal degradability of DM and CP. Both goats and wethers fed olive leaves showed similarly low particulate fractional passage rates (0.021 and 0.023/h, respectively). Ingestion of olive leaves promoted low NH3-N and VFA concentrations, which reflect poor microbial activity. These concentrations, especially that of VFA, increased when barley and faba beans were added. Ingestion of olive leaves affected ruminal protozoa: Entodiniomorphida showed low concentrations and Holotricha completely disappeared. When animals received a diet based on olive leaves, barley, and faba beans, Holotricha appeared in the ruminal liquor and Entodiniomorphida increased (P < 0.001). In goats and wethers fed olive leaves alone, urinary allantoin excretion was very low (163 and 164 micromol/kg BW0.75 in goats and wethers, respectively), and moderate values (352 and 389 micromol/kg BW0.75 in goats and wethers, respectively) were observed when a diet of olive leaves, barley, and faba beans was fed. The polyethylene glycol supply did not have an effect in goats or in wethers, indicating the lack of an effect of condensed tannins in olive leaves. Ingestion of olive leaves promotes a low microbial activity, although its supplementation with readily degraded carbohydrates and protein improves microbial activity and, as a consequence, increases its ruminal degradation. In general, for most of the measured variables, there were no animal species x diet interactions. Thus, goats and wethers had similar ruminal activities when fed diets based on olive leaves.     

陕北白绒山羊皮肤毛囊形态结构及其特征参数与产绒性状的相关性分析

试验旨在研究陕北白绒山羊皮肤毛囊结构及其特征参数与产绒性状间的相关性,为绒山羊绒毛生长的分子调控机理研究及皮肤毛囊性状在绒山羊选育中的应用提供参考。通过制作陕北白绒山羊皮肤组织切片,用显微照相系统观察皮肤毛囊形态特征,统计分析皮肤和毛囊的特征参数,并用SPSS 17.0软件分析特征参数与产绒性状各指标的相关性。结果显示,陕北白绒山羊毛囊成群分布且以三元型毛囊群为主,占总毛囊群的85.80%;产绒量与体重、绒长度、S/P值、次级毛球宽度均呈极显著正相关（P<0.01）,与次级毛囊密度呈显著正相关（P<0.05）,与表皮厚度呈显著负相关（P<0.05）;绒长度与产绒量、次级毛球宽度均呈极显著正相关（P<0.01）,与体重、S/P值、次级毛囊直径均呈显著正相关（P<0.05）,与表皮厚度呈显著负相关（P<0.05）;绒细度与S/P值呈显著负相关（P<0.05）;S/P值影响绒细度,而体重、绒长度、S/P值、次级毛囊密度（绒密度）显著影响产绒量（P<0.05）。综合分析认为,S/P值可以作为陕北白绒山羊选种工作中的一个重要性状指标,在育种工作中选择高S/P值个体,不仅能够提高产绒量,而且能够提高绒长度、降低绒细度,解决产绒量和绒品质同时提高的矛盾。