The aim of the present study was to study the effects of forage/concentrate ratio, year, parity and number of kids on milk yield (MY), lactation length (LL) and milk composition (fat, protein and lactose) on 180 Maltese goats analysing 530 milk samples collected from 2000 to 2002.
The main average results were: MY = 288.2 kg, LL = 254 d with 3.5% fat, 3.4% protein and 4.6% lactose.
Forage/concentrate ratio significantly affected MY and fat being highest in goats receiving a ratio of 65/35. Milk yield in goats fed with a ratio of 35/65 was richer in fat (3.6%). The protein and lactose content was not affected by the different ratios. The effect of diet on fat content was small but significant. Parity influenced all the factors considered, in particular goats in ≥4th parity, had longer LL (257 d) and consequently a higher milk yield (302.1 kg). Goats kidding twins yielded more milk and had longer lactation (P < 0.001). 相似文献
We examined the extent of linkage disequilibrium (LD) block lengths in four breed populations: Japanese Black, Angus, Hereford and Holstein. Three chromosomal regions in which QTL were previously mapped in Japanese Black populations were scanned with 84 microsatellite markers. The estimated LD lengths in these four purebred populations varied from 535 to 683 kb, which is much shorter than the values reported previously. Our findings suggest that QTL can be mapped in sub-centimorgan regions in these populations using an LD-mapping method. We also developed breed identification methods to distinguish Japanese Black from Angus, Hereford, Holstein and F1 animals (Japanese Black × Holstein) respectively using the haplotypic frequencies of a pair of markers in the breed populations. After assessing the distributions of posterior probabilities to be Japanese Black, we obtained several pairs of markers that completely distinguished Japanese Black from the other breeds. We also obtained several combinations of six markers that completely distinguished Japanese Black animals from F1 animals. 相似文献
Three feeding trials with different dietary treatments were conducted to evaluate predictions of dry matter intake and average daily gain of Chinese local beef cattle by Cornell Net Carbohydrate and Protein System (CNCPS) version 5.0. In Trial 1, 60 growing Jin Nan yellow steers (local yellow cattle breed originated from Shanxi Province) were assigned to two treatments with five pens in each treatment and six animals in each pen. Trial 2 was conducted with 72 Lu Xi yellow growing steers (local yellow cattle breed originated from Shandong Province) in 12 conventional pens. These animals were assigned to four treatments with six animals in each pen. In Trial 3, 60 Lu Xi yellow steers were allocated to four treatments with five animals in each pen. Average daily dry matter intake (DMI) for each steer was measured as a mean of each pen. All the data about animals, environment, management and feeds required by the CNCPS model were collected, and model predictions were generated for animals of each pen. Model predictions were evaluated by mean bias, mean square prediction error (MSPE) and regression between the observed and predicted values. Animals in 9 of 10 treatments showed a very close model-predicted DMI values to the observed. In another treatment, animals had a mean bias of −0.72 kg DM/day (TRT 10 in Trial 3). With overall data included, the regression equation between observed and predicted DMI was: YOBS = 1.10XCNCPS − 0.78 (R2 = 0.82; P<0.0001), with an intercept not different (P=0.32) from zero, but a slope still different (P<0.0001) from 1. Although the model-predicted ADG values were very close to the observed values in all trials, most of the predicted values were always lower than the observed values with absolute mean bias less than 0.2. When all data were pooled, the regression equation between observed and predicted ADG was: YOBS = 1.07XCNCPS + 0.02 (R2 = 0.73; P<0.0001), with an intercept not different from zero (P=0.88), but a slope that differed from unity (P<0.0001). Results suggest that the CNCPS model is an acceptable model to predict dietary DM intake and average daily gain of Chinese local beef cattle breeds. Further studies are warranted to introduce model adjustment for Chinese conditions. 相似文献
To examine the effects of maternal energy restriction along with selenium-methionine (Se-Met) and chromium-methionine (Cr-Met) supplementation on performance of pregnant sheep and their offspring, the following treatments were allotted randomly to 40 multiparous Baluchi ewes (53.9 ± 1.15 kg of body weight [BW]) from 5 weeks prior to 5 weeks after parturition: (1) Control diet (60% and 100% of NRC energy requirements in pre- and post-partum, respectively); (2) Control diet plus 5 mg Se-Met/kg dry matter (DM); (3) Control diet plus 3 mg Cr-Met/kg DM and (4) Control diet plus 5 mg Se-Met and 3 mg Cr-Met/kg DM (Se–Cr-Met) of concentrate diet. The results indicated that Cr-Met alone or in combination with Se-Met increased average DM intake of ewes. In addition, Group Cr-Met had higher average BW than the Control (p < 0.05). Se-Met and/or Cr-Met supplementation led to decreased average serum cholesterol of the ewes (p < 0.05). Groups Cr-Met and Se–Cr-Met displayed decreased average serum malondialdehyde compared to the Control (p < 0.05). At 24 h post-partum, Group Se–Cr-Met had a greater serum Se content than the Control (p = 0.006). Compared with the Control, the Se concentration in milk was significantly increased from 30 to 138 µg/l and 197 µg/l in Groups Se-Met and Se–Cr-Met, respectively (p < 0.01), which proved that Se-Met supplementation can increase the Se concentration of ewe milk. Furthermore, feeding Cr-Met may attenuate BW loss post-partum and Se-Met and/or Cr-Met supplements may ameliorate oxidative stress condition in ewes around parturition. 相似文献
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. 相似文献
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. 相似文献
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 FST = 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. 相似文献
Growth hormone (GH) exerts its effects on growth and metabolism by interacting with a specific receptor (GHR) on the surface of the target cells. Therefore, GHR has been suggested as candidate gene for traits related to meat production in cattle. The aim of the study was to analyse the polymorphism at position 257 in exon 10 of the GHR gene and investigate relationships with 14 in vivo traits and four meat characteristics in Piemontese animals. The biallelic polymorphism already described was detected using a new PCR procedure. The statistical analysis did not show significant gene substitution effects on growth, size and meat conformation traits. As for meat characteristics, a significant gene substitution of GHR(A) over GHR(G) was observed for drip losses at day 3, with the allele GHR(A) associated with higher values. A significant dominance effect was also observed for this trait. Further investigations in other breeds will be useful for better understanding information on the effect of this GHR polymorphism. 相似文献