Surface analysis of sheep menisci after meniscectomy via infrared attenuated total reflection spectroscopy

Menisci are very important fibrocartilaginous tissue, which maintain biomechanical functions and physiological stabilization of knee joint. Meniscectomy is known as a surgery to recover partial functions from acute meniscus tears. However, the late consequences of total or partial meniscectomy include signs of osteoarthritis and even ligament instability. Infrared attenuated total reflection (IR‐ATR) spectroscopy is a very useful technique, which can reveal molecular characteristics via the analysis of vibrational bands. The present study has employed IR‐ATR spectroscopy to investigate sheep menisci samples after meniscectomy in a label‐free fashion. Several differences of peak absorbance change and peak shift were observed between the native healthy samples and the meniscectomy samples in distinct IR wavenumber regions, such as amide I band, amide II band, C‐H bending band as well as the sugar band region. Combining the results from the collagen protein IR spectra, it can be speculated that six months after meniscectomy collagen fibrils on the incision lose its ordered arrangement and a decrease in the triple helical structure of collagen fibril is observed. In addition, the collagen fibrils and proteoglycan content might also be slight varied after meniscectomy.      

Diet selection of sheep shifted from quality to quantity characteristics of forages as sward availability decreased

Understanding the dynamic inter-relationship between grazing animals and the pasture sward is critical for sustainable grazing management. A field study was conducted to investigate the relationships between the quantity and quality characteristics of forages and diet selection of 30-kg Mongolian ewes in different seasons in Bromus inermis improved meadow steppe. Using a residual herbage mass method (1 000 kg/ha in spring, 800 kg/ha in summer and 600 kg/ha in autumn) to adjust stocking rate, three seasonal rest grazing strategies (spring rest, summer rest and autumn rest) combined with continuous grazing were studied. In each season, diet selection of sheep, quantified by diet composition and selectivity index, was estimated using a plant wax marker technique. Quantity (dry weight proportion, coverage, frequency, density and height) and quality (CP, NDF, ADF and DM digestibility) characteristics of forages consumed by sheep were determined simultaneously. Our results showed that in spring with the highest sward availability (herbage mass), diet selection of sheep could be predicted by the positive linear relationship between quality characteristics of forages and their selectivity index. In summer, the diet selection could be predicted by both positive linear relationship between quality characteristics and selectivity index, and the relationship between quantity characteristics and diet composition. While in autumn with the lowest sward availability, it could be predicted by the positive linear relationship between quantity characteristics and diet composition. During the whole grazing season, the diet composition of B. inermis (40.4%) and Leymus chinensis (35.1%) were larger than that of Potentilla bifurca (9.5%) and Carex (15.1%) and the selectivity index of P. bifurca was the highest (0.62), followed by Carex (0.17) and B. inermis (0.05), and L. chinensis (?0.29) was the lowest. The two parameters of diet selection above were positively related to their quantity and quality characteristics, respectively. These results suggested that the influence of quality characteristics on diet selection of sheep decreased gradually as a result of the decline in sward availability, while the influence of quantity characteristics increased. This study provides a comprehensive understanding of diet selection of sheep examining the trade-offs between quantity and quality characteristics of forages. The knowledge of diet selection of sheep and the corresponding prediction regressions acquired in this study could give the basis for designing appropriate grazing management strategies.     

Mapping quantitative trait Loci underlying fitness-related traits in a free-living sheep population

We searched for quantitative trait loci (QTL) underlying fitness-related traits in a free-living pedigree of 588 Soay sheep in which a genetic map using 251 markers with an average spacing of 15 cM had been established previously. Traits examined included birth date and weight, considered both as maternal and offspring traits, foreleg length, hindleg length, and body weight measured on animals in August and jaw length and metacarpal length measured on cleaned skeletal material. In some cases the data were split to consider different age classes separately, yielding a total of 15 traits studied. Genetic and environmental components of phenotypic variance were estimated for each trait and, for those traits showing nonzero heritability (N= 12), a QTL search was conducted by comparing a polygenic model with a model including a putative QTL. Support for a QTL at genome-wide significance was found on chromosome 11 for jaw length; suggestive QTL were found on chromosomes 2 and 5 (for birth date as a trait of the lamb), 8 (birth weight as a trait of the lamb), and 15 (adult hindleg length). We discuss the prospects for refining estimates of QTL position and effect size in the study population, and for QTL searches in free-living pedigrees in general.     

Methodological developments in the use of visible reflectance spectroscopy for discriminating pasture-fed from concentrate-fed lamb carcasses

The ability to authenticate the feed given to animals from the animal products has become a major challenge for scientists, monitoring bodies and commercial entities alike. This study compared two methods based on the use of the visible reflectance spectrum of the fat to discriminate pasture-fed (P) from stall concentrate-fed (S) lamb carcasses. A total of 307 (143 P and 164 S) Limousine lambs were used over 2 years. Pasture-fed lambs grazed a permanent pasture that was maintained at a leafy, green vegetative stage, and offered ad libitum; they received no supplementation at pasture. Body weight of P lambs when turning out to pasture and at slaughter averaged 9.2 (standard deviation (s.d.) 2.21) kg and 33.2 (s.d. 2.89) kg, respectively. S lambs were fed indoors on an ad libitum diet of commercial concentrate and hay until slaughter at a mean body weight of 33.7 (s.d. 3.62) kg. The reflectance spectrum of perirenal and subcutaneous caudal fat was measured at slaughter and at 24 h post mortem. Plasma carotenoid concentration was measured at slaughter. In method 1, the fat reflectance spectrum data were used at wavelengths between 450 and 510 nm to calculate an index quantifying light absorption by carotenoid pigments. In method 2, a multivariate analysis was performed over the full set of fat reflectance data at wavelengths between 400 and 700 nm. Method 2 yielded a higher proportion of correctly classified lambs compared with method 1 (P < 0.05 to 0.001), except for measurements made at 24 h post mortem on perirenal fat for S lambs. The proportion of lambs correctly classified using method 2 was 87.4% and 92.9% for measurements made on perirenal and caudal fat at slaughter, and 93.9% and 91.0% for measurements made on perirenal and caudal fat 24 h post mortem. Plasma carotenoid concentrations were higher in P lambs than in S lambs (P < 0.001), which led to correct classification of 90.7% of the lambs.     

Feeding habitats of blue sheep (Pseudois nayaur) during winter and spring in Helan Mountains, China

The feeding habitat selection of blue sheep (Pseudois nayaur) was studied by direct observation method in the Helan Mountains, China during winter (from November to December) and spring (from April to June) from 2003 to 2004. We established 25 line transects to collect information on feeding habitats used by blue sheep. Blue sheep in the study area preferred mountain savanna forests, a habitat dominated by Ulmus glaucescens, with medium tree density (<4 individuals / 400 m²), moderate tree height (4–6 m), higher shrub density (> 5 individuals / 100 m²), higher shrub (> 1.3 m), higher food abundance (> 50 g), moderate distance to human disturbance (< 500 m), and mild distance to bare rock (< 2 m). Such habitats characterized by 12 ecological factors were preferred as feeding areas by blue sheep during winter. Similar to habitat selection by the species during winter, blue sheep also showed a preference for mountain savanna with tree dominated by Ulmus glaucescens and medium tree density (< 4 individuals / 400 m²) during spring. Nevertheless, blue sheep preferred medium tree height (< 6 m), moderate tree density (5–10 individuals / 100 m²), medium shrub height (1.3–1.7 m), higher food abundance (> 100 g), moderate altitude (< 2 000 m), moderate distance to water resource (< 500 m), and medium hiding cover (50%–75%) during spring. Selection of the feeding habitats by sheep showed a significant difference in vegetation type, landform feature, dominant tree, tree height, shrub density, distance to the nearest shrub, food abundance, slope direction, slope degree, distance to water resource, and hiding cover between winter and spring. Results of principal components analysis indicated that the first principal component accounted for 24.493% of the total variance among feeding habitat variance during winter, with higher loadings for vegetation type, dominant tree, tree height, distance to the nearest tree, shrub density, shrub height, altitude, distance to water resource, and distance to human disturbance. In spring, the first principal components explained 28.777% of the variance, with higher loadings for vegetation type, distance to the nearest tree, shrub height, distance to the nearest shrub, food abundance, altitude, and distance to human disturbance. Translated from Zoological Research, 2005, 26(6): 580–589 [译自: 动物学研究]     

绵羊肌肉中FAS基因和HSL基因的发育性变化及其对肌内脂肪含量的影响

选取不同日龄的雄性哈萨克羊和新疆细毛羊共54只,屠宰后取背最长肌,用索氏抽提法检测肌内脂肪(intramuscular fat,IMF)含量,用荧光实时定量PCR法检测肌肉脂肪酸合成酶(fatty acid synthase,FAS)和激素敏感脂肪酶(hormone-sensitive lipase,HSL)基因表达的发育性变化,并分析基因表达对肌内脂肪沉积的影响。结果表明:1)随着日龄的增加,雄性哈萨克羊的IMF含量持续上升,各生长时期差异显著(P<0.05),而新疆细毛羊的IMF含量在各生长时期无显著差异(P>0.05)。雄性哈萨克羊的IMF含量30~90日龄期间极显著高于新疆细毛羊(P<0.01)。2)FAS基因mRNA水平在哈萨克羊肌肉中初生时最高(P<0.05),然后随日龄的增加呈下降趋势;在新疆细毛羊肌肉中,FAS mRNA水平表现出"下降-上升-下降-上升"的发育模式,其中60日龄显著高于90日龄(P<0.05),其余日龄之间差异不显著。HSL基因在2品种绵羊肌肉中的表达模式基本类似,在哈萨克羊肌肉中随年龄的增加而下降,初生时的水平显著高于60~90日龄(P<0.05);在新疆细毛羊中30日龄时达到最高(P<0.01),到60日龄时下降到最低(P<0.05),随后保持这种低表达水平。3)FAS和HSL基因mRNA的表达量均与哈萨克羊IMF含量呈负相关,相关系数分别为:r=-0.485(P=0.02),r=-0.423(P=0.05);在哈萨克羊中两基因表达量水平比值(FAS:HSL)与IMF呈极显著负相关r=-0.552(P=0.01)。在新疆细毛羊中两基因的表达水平及比值均与IMF无显著相关性(P>0.05)。     

高原型藏羊和小尾寒羊睾丸小叶及附睾微动脉的解剖学特征

分别从青海和甘肃采集高原型藏羊(Ovis aries)和小尾寒羊睾丸各20枚,用血管铸型技术和扫描电镜方法,研究两品种绵羊睾丸小叶及附睾微动脉的超微形态特征。结果显示,两品种绵羊的睾丸小叶及附睾微动脉走形呈一定程度的弯曲,其中睾丸小叶内离心动脉、离心小动脉及向心小动脉均呈"树枝"状分布。研究发现,与低海拔地区的小尾寒羊相比,高原型藏羊睾丸的绳结状动脉具有更密集的螺旋状排布,小动脉分支也较多,并且向心动脉、绳结状动脉、离心动脉、附睾头微动脉的管径也较粗。此外,高原型藏羊睾丸小叶和附睾头微动脉表面的"梭形"压痕较浅,而小尾寒羊的则较深;高原型藏羊睾丸小叶毛细血管前微动脉的表面缢痕较多且密集,而小尾寒羊的则相对少而稀疏。研究认为,高原型藏羊睾丸小叶及附睾微动脉的超微形态特征,有利于血管的收缩、睾丸供血及高原环境下精子的成熟,是睾丸对高原环境的适应性特征。