Genetic diversity of eleven European pig breeds

A set of eleven pig breeds originating from six European countries, and including a small sample of wild pigs, was chosen for this study of genetic diversity. Diversity was evaluated on the basis of 18 microsatellite markers typed over a total of 483 DNA samples collected. Average breed heterozygosity varied from 0.35 to 0.60. Genotypic frequencies generally agreed with Hardy-Weinberg expectations, apart from the German Landrace and Schwäbisch-Hällisches breeds, which showed significantly reduced heterozygosity. Breed differentiation was significant as shown by the high among-breed fixation index (overall F_ST = 0.27), and confirmed by the clustering based on the genetic distances between individuals, which grouped essentially all individuals in 11 clusters corresponding to the 11 breeds. The genetic distances between breeds were first used to construct phylogenetic trees. The trees indicated that a genetic drift model might explain the divergence of the two German breeds, but no reliable phylogeny could be inferred among the remaining breeds. The same distances were also used to measure the global diversity of the set of breeds considered, and to evaluate the marginal loss of diversity attached to each breed. In that respect, the French Basque breed appeared to be the most "unique" in the set considered. This study, which remains to be extended to a larger set of European breeds, indicates that using genetic distances between breeds of farm animals in a classical taxonomic approach may not give clear resolution, but points to their usefulness in a prospective evaluation of diversity.     

Are DNA profiles breed‐specific? A pilot study in pigs

In this study, DNA fingerprints from 32 unrelated domestic pigs were analysed and screened for breed-specificity. Three breed groups were analysed: Chinese Meishan, Large White and a collection of other European breeds. Ninety-three distinct and variable bands were used to estimate genetic distances between the animals. Between the groups these individual genetic distances substantially exceeded those within a group. Linear discriminant analysis showed that the 23 most common DNA fragments revealed sufficient breed-specificity as to assign each pig correctly to its breed or breed group. These findings, although based on a small sample, indicate that selective use of minisatellite variation in pigs appears to be a valuable novel approach toward the development of breed DNA profiles and the resolution of breed relationships.     

光合细菌的分离鉴定及对养殖水的净化研究

水质的恶化是影响水生生物存活率和产量的主要障碍 ,因此如何净化水质已成为养殖技术的难点和研究热点。从养虾池底泥分离得到 4株光合细菌 (PSB) ,经初步鉴定分别为纤细红螺菌、球形红假单胞菌和沼泽红假单胞菌 ;将其混合培养后处理养虾池水 ,结果表明 ,PSB可以有效分解底泥中污染物 ,去除水体中的COD、氨氮 (第 4dCOD去除率为 72 .5 9% ,氨氮去除率达 89.2 % ) ,养殖池PSB的使用量以 1mg/L为宜。     

Production objectives,trait and breed preferences of farmers keeping N’Dama,Fulani Zebu and crossbred cattle and implications for breeding programs

Many local livestock breeds in developing countries are being replaced by exotic breeds, leading to a loss of genetic resources. In southern Mali, for the past two decades, a trend towards increasing crossbreeding between the trypanotolerant N’Dama cattle and the trypano-susceptible Fulani Zebu cattle has been taking place. A survey with 160 farmers owning a cattle herd was carried out in southern Mali to investigate their production objectives, as well as trait and breed preferences and correlated socio-economic determinants in order to understand farmers’ breeding decisions and to identify comparative advantages of three breed groups (N’Dama, Fulani Zebu and crossbreds) raised in the study area. Data were analyzed using an exploded logit model. The reasons for raising cattle, as well as trait and breed preferences reflected the multiple objectives of the farmers. Draught power and savings were the most important production objectives. Productive traits were ranked highest; farmers reported large body size as the most preferred trait, followed by fertility, draught ability and milk yield. Crossbreds were the favored breed group. Breed preferences were mainly explained by ‘resistance to disease’ for N’Dama cattle and ‘high market price’ for Fulani Zebu and crossbred cattle. Production objectives, trait and breed preferences were mainly influenced by farmer group (local farmers and settled transhumants). Local farmers put comparatively more emphasis on livestock functions linked to crop production such as draught power. They had a higher preference for traction ability as a selection trait and preferred N’Dama over Fulani Zebu cattle. Settled transhumants emphasized milk yield as a selection trait and preferred Fulani Zebu over N’Dama. The results indicate that the trend towards more crossbreeding will continue putting the N’Dama breed under high risk of genetic dilution in southern Mali. The N’Dama cattle remain a valuable breed due to their adaptive traits such as disease and drought tolerance and their good traction ability, fulfilling the diverse objectives of local farmers. Crossbreeding was found to be a promising breeding strategy, which might contribute to the maintenance of the local breed, provided that breeding schemes are thoroughly planned and organized.     

Influence of breed on blood and tissue copper status in growing and finishing steers fed diets supplemented with copper

To evaluate the influence of breed on the accumulation of dietary copper (Cu) in tissue, and on blood parameters indicative of Cu status, ten Galician Blond, nine Holstein-Friesian and ten Galician Blond × Holstein-Friesian cross (GB × HF) steers were fed diets supplemented with 35 mg/kg DM of CuSO₄ during their growing and finishing periods. Blood samples were taken monthly, and samples of liver, kidney, brain, heart, spleen and muscle were taken at slaughter. Cu concentrations were determined by ICP-AES. Holstein-Friesian calves had significantly higher total liver Cu contents than Galician Blonds and GB × HF crosses (mean 1070, 663 and 868 mg, respectively), combined with higher hepatic Cu concentrations (174, 140 and 166 mg/kg wet weight, respectively). Holstein-Friesian calves had also the highest prevalence (89%) of hepatic Cu concentrations exceeding the toxic limit of 150 mg/kg wet weight. Breed did not have a statistically significant influence on blood parameters. With the exception of the semitendinosus muscle, where Holstein-Friesians (0.790 mg/kg) had significantly higher Cu levels than Galician Blonds (0.541 mg/kg) or GB × HF crosses (0.631 mg/kg), no other statistically significant differences by breed in the extrahepatic tissue Cu distribution were observed. A negative statistical association between carcass performance and the ratio of semitendinosus and liver Cu concentration could indicate that the animals with a better carcass performance (Galician Blonds) could need a higher Cu mobilisation into the muscle, resulting in a lower hepatic storage.     

Comparison of DMRT3 genotypes among American Saddlebred horses with reference to gait

Horse owners choose whether or not to train American Saddlebred horses (ASHs) to perform the 4‐beat gaits called rack and slow gait. The rack and slow gait are similar to ambling gaits shown to be associated with variation in the DMRT3 gene in other breeds but are trained rather than naturally occurring gaits. A premature stop codon in the DMRT3 gene (DMRT3_Ser301STOP) caused by the Ch23:g.22999655C>A SNP has an effect on the pattern of locomotion in horses and allows for the pacing gait and strong association with performance of ambling gaits in diverse breeds. We used horse show records to identify ASHs trained to perform as 5‐gaited horses and compared them to other Saddlebreds for the prevalence of the A allele of the Ch23:g.22999655C>A SNP of DMRT3. Genomic DNA was typed using a PCR‐RFLP technique for 5‐gaited ASHs (n = 55), 3‐gaited or harness ASHs (n = 64) and ASHs not shown (n = 128). We did not observe differences in the frequencies of the Ch23:g.22999655C>A SNP of DMRT3 when comparing 5‐gaited ASHs to other ASHs (P > 0.22). These results suggest that DMRT3 alleles do not affect the choice of breeders to train and show ASHs as 5‐gaited horses.     

Genetic parameters of traits associated with the growth curve in Segureña sheep

This paper studies the genetic importance of growth curve parameters and their relevance as selection criteria in breeding programmes of Segureño sheep. Logistic and Verhulst growth functions were chosen for their best fit to BW/age in this breed; the first showed the best general fit and the second the best individual fit. Live weights of 41 330 individuals from the historical archives of the National Association of Segureña Sheep Breeders were used in the analysis. The progeny of 1464 rams and 27 048 ewes were used to study the genetic and phenotypic parameters of growth curve parameters and derived traits. Reproductive management in the population consists in controlled natural mating inside every herd, with a minimum of 15% of the females fertilized by artificial insemination with fresh semen; with the purpose being the herd genetic connections, all herd genealogies are screened with DNA markers. Estimates of growth curve parameters from birth to 80 days were obtained for each individual and each function by the non-linear regression procedure using IBM SPSS statistics (version 21) with the Levenberg–Marquart estimation method. (Co)variance components and genetic parameters were estimated by using the REML/Animal model methodology. The heritability of mature weight was estimated as 0.41±0.042 and 0.38±0.021 with the logistic and Verhulst models, respectively, and the heritability of other parameters ranged from 0.41 to 0.62 and 0.37 to 0.61, with the models, respectively. A negative genetic correlation between mature weight and rate of maturing was found.     

长江中下游热量资源时空演变特征及其对双季稻种植的影响

热量资源的时空特征是影响双季稻种植布局的主要气候因素.为了分析近52年长江中下游主要双季稻区热量资源的变化特征及其对双季稻种植的影响,本研究选取湖南、江西和湖北3省作为双季稻代表性研究区域,根据3省240个气象站1961—2012年的地面气象观测资料,利用气候倾向率及突变分析等方法,分析研究区双季稻温度生长期的热量资源和双季稻的安全生长期的演变规律,在此基础上分析研究时段内不同水稻品种搭配布局及种植北界的变迁.结果表明: 近52年双季稻温度生长期及安全生长期的热量资源均呈明显增多趋势,其中,双季稻生长期及安全生长期的热量资源由寡至多的突变点均出现在2000年;双季早稻安全播种期提前3～7 d、双季晚稻安全齐穗期延后2 d,双季稻安全生长期平均延长7 d;双季稻种植北界明显北移了200 km左右,至33° N附近;同时,双季稻品种搭配由“早熟早稻+中熟晚稻”和“中熟早稻+中熟晚稻”向“中熟早稻+晚熟晚稻”转变.长江中下游双季稻区热量资源的增加为双季稻种植北界北移、中晚熟品种替代早中熟品种提供了可能.     

Genetic parameters and genetic trends in the Chinese × European Tiameslan composite pig line. I. Genetic parameters

Genetic parameters of body weight at 4 (W4 w), 8 (W8 w) and 22 (W22 w) weeks of age, days from 20 to 100 kg (DT), average backfat thickness at 100 kg (ABT), teat number (TEAT), number of good teats (GTEAT), total number of piglets born (TNB), born alive (NBA) and weaned (NW) per litter, and birth to weaning survival rate (SURV) were estimated in the Chinese × European Tiameslan composite line using restricted maximum likelihood methodology applied to a multiple trait animal model. Performance data from a total of 4 881 males and 4 799 females from 1 341 litters were analysed. Different models were fitted to the data in order to estimate the importance of maternal effects on production traits, as well as genetic correlations between male and female performance. The results showed the existence of significant maternal effects on W4w, W8w and ABT and of variance heterogeneity between sexes for W22w, DT, ABT and GTEAT. Genetic correlations between sexes were 0.79, 0.71 and 0.82, respectively, for W22w, DT and ABT and above 0.90 for the other traits. Heritability estimates were larger than (ABT and TEAT) or similar to (other traits) average literature values. Some genetic antagonism was evidenced between production traits, particularly W4w, W8w and ABT, and reproductive traits.     

Effect of breed, gender, housing system and dietary crude protein content on performance of finishing beef cattle fed maize-silage-based diets

Maize silage-based diets with three dietary crude protein (CP) supplements were offered to 96 finishing cattle of contrasting breed (Holstein Friesian (HF) v. Simmental × HF (SHF)) and gender (bull v. steer) housed in two types of feeding system (group fed v. individually fed). The three protein supplements differed either in CP or protein degradability (degradable (LUDP) v. rumen undegradable (HUDP)) and provided CP concentrations of 142 (Con), 175 (LUDP) and 179 (HUDP) g/kg dry matter (DM) respectively, with ratios of degradable to undegradable of 3.0, 1.4 and 0.9:1 for diets Con, LUDP and HUDP, respectively. DM intakes were marginally higher (P = 0.102) for LUDP when compared with Con and HUDP. Rates of daily live-weight gain (DLWG) were higher (P = 0.005) in LUDP and HUDP when compared with Con. HF had higher DM intakes than SHF although this did not result in any improvement in HF DLWG. Bulls had significantly better DM intakes, DLWG and feed conversion efficiency than steers. Conformation scores were better in SHF than HF (P < 0.001) and fat scores lower in bulls than steers (P < 0.001). There was a number of first order interactions established between dietary treatment, breed, gender and housing system with respect to rates of gain and carcass fat scores.