辽宁绒山羊年龄与绒毛生产性能的关系

为研究辽宁绒山羊年龄与绒毛生产性能的关系,对1～8岁辽宁绒山羊产绒性能与绒毛品质性状进行了研究.结果表明:①周岁羊绒细度最细(14.31 μm),随年龄增加羊绒细度变粗,6岁时达到最粗(18.02 μm),而后缓慢下降.②周岁羊绒产量最低(508.21g),5岁羊绒产量最高(790.30 g),5～8岁羊绒产量差异不显著.③1～8岁内在3岁和5岁时出现了两个绒长高峰,分别为7.62 cm和7.61 cm,3～6岁阶段羊绒长度变化差异不显著.④一般认为,细度和长度与绒纤维品质最为密切,1～2岁绒纤维直径虽小,但因其长度和产绒量均很低,不是产绒性能和绒毛品质的最佳阶段.2～4岁时绒细度适中、绒长较长、绒纤维品质较高,然而其产绒量很低同样降低了经济效益.6～8岁绒产量较高且绒长下降平缓,但其绒纤维直径较粗且降低幅度小,因而不可作为产绒性能和绒毛品质的最佳阶段.由上述可知,4～5岁年龄段的羊产绒性能和绒毛品质处于最佳阶段,可适当增加4～5岁羊在群体中的比例.     

Dynamic changes of genomic methylation profiles at different growth stages in Chinese Tan sheepOA

Background: Tan sheep, an important local sheep breed in China, is famous for their fur quality. One-month-old Tan sheep have white, curly hair with beautiful flower spikes, commonly known as "nine bends", which has high economic value. However, the "nine bends" characteristic gradually disappears with age; consequently, the economic value of the Tan sheep decreases. Age-related changes in DNA methylation have been reported and may be responsible for age-induced changes in gene expression. Until...     

Village production of West African Dwarf goats and sheep in Nigeria

Results from a 41 month study of West African Dwarf goats and sheep under village conditions in south-west Nigeria are reported. Even at a very low level of management these trypanosomiasis-tolerant animals produced 2.01 kids or 1.51 lambs per dam per year. Mortality of young particularly kids and low growth rates limit production. Of these mortality is probably the first constraint to increased productivity and profitability. Control of peste des petits ruminants appears to significantly reduce mortality and should stimulate the further development of this production system.     

Relationship between growth hormone (GH) pulses in the peripheral circulation and GH-releasing hormone and somatostatin profiles in the cerebrospinal fluid of goats

Growth hormone (GH) is secreted in a pulsatile manner, but the underlying mechanisms of GH pulse generation remain to be resolved. In the present study, we investigated the relationship between GH pulses in the peripheral circulation and GH-releasing hormone (GHRH) and somatostatin (SRIF) profiles in the cerebrospinal fluid (CSF) of male goats. The effects of an intracerebroventricular (icv) injection of neuropeptide Y (NPY), galanin and ghrelin were also analyzed. Blood and CSF samples were collected every 15 min for 8 hr from the jugular vein and third ventricle, respectively. GH pulsatility in the goat was found to consist of distinct large pulses of 5 hr periodicity and small pulses of 1 hr periodicity. GHRH and SRIF in the CSF fluctuated in a pulsatile manner with 1 hr periodicity, and most of the descending phase of SRIF pulses were associated with the initiation of GH pulses. Icv injections of NPY, galanin and ghrelin stimulated GHRH release without affecting SRIF release. In addition, NPY suppressed, and galanin and ghrelin induced large GH pulses, although ghrelin was much more effective than galanin. These results suggest that an hourly fall in SRIF is involved in generating intrinsic circhoral rhythm of GH pulsatility. The mechanisms underlying the generation of large GH pulses of 5 hr periodicity remain unknown, while direct action of NPY and/or ghrelin on the pituitary might be involved.     

Milk production of West African Dwarf goats in The Gambia

Goats are important in the low-input systems of West Africa and their main importance lies in their role for income and saving. In addition, it is known that milk offtake for home consumption is also important. In order to obtain information about the real importance of milk offtake, a recording scheme was operated in 27 villages in the Central River Division of The Gambia from July 1998 until January 2000. Detailed information was obtained from about 1500 kiddings. In the recording scheme, any sheep being milked as well as the goats of the International Trypanotolerance Centre nucleus flock were also recorded. In the villages, 36% of all lactations were used for milk offtake, but the fraction milked was lower for the first two lactations. The average length of lactation was 127 days and the average daily milk offtake was 0.18 L. Goats are milked once a day and the residual milk is left for the kids. Milking starts about one week after parturition and stops when the goat becomes pregnant or the kid(s) die or the goat is drying off. The repeatability of the 90-day milk offtake was 0.24 ± 0.09. Sixty-five percent of goat owner were women and a large fraction of goat owners also owned cattle. Goat milk was used exclusively for home consumption. It is concluded that in breeding and extension work more attention should be given to aspects of milk production.     

Effects of steam-treated rice straw feeding on growth,digestibility, and plasma volatile fatty acids of goats under different housing systems

In order to use rice straw as forage in livestock feeding, the effects of steam-treated rice straw (at 15.5 kgf/cm² for 120 s) feeding on growth performance, plasma volatile fatty acid profile, and nutrient digestibility of goats were determined. Twenty male goats (18.69?±?0.34 kg) were used in an 84-day trial. The goats were divided into four groups of five goats each to receive steam-treated (STRS) or untreated (UTRS) rice straw diet under closed house (CH) and open house (OH) systems. The results revealed that the goats fed with STRS had significantly higher dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) digestibility; similarly, the average daily weight gain and feed conversion ratio were higher for STRS groups under both CH and OH systems than those for UTRS. The plasma protein and insulin in STRS and cholesterol in UTRS groups was higher (P?P?>?0.05) at 30 days. The plasma amylase, lipase, T₃, T₄ and glucagon at 30 and 60 days were not different (P?>?0.05) among the groups. The plasma acetate, propionate, butyrate, and total volatile fatty acid were higher (P?P?>?0.05) on these parameters. It could be concluded that steam treatment of rice straw at 15.5 kgf/cm² for 120 s increased apparent nutrient digestibility, hence increased the growth and feed efficiency of growing goats.     

Microbiological quality of goat's milk obtained under different production systems

In order to determine the safety of milk produced by smallholder dairy goat farms, a farm-based research study was conducted on commercial dairy goat farms to compare the microbiological quality of milk produced using 3 different types of dairy goat production systems (intensive, semi-intensive and extensive). A survey of dairy goat farms in and around Pretoria carried out by means of a questionnaire revealed that most of the smallholder dairy goat farms surveyed used an extensive type of production system. The method of milking varied with the type of production system, i.e. machine milking; bucket system machine milking and hand-milking, respectively. Udder half milk samples (n=270) were analysed, of which 31.1% were infected with bacteria. The lowest intra-mammary infection was found amongst goats in the herd under the extensive system (13.3%), compared with 43.3% and 36.7% infection rates under the intensive and semi-intensive production systems, respectively. Staphylococcus intermedius (coagulase positive), Staphylococcus epidermidis and Staphylococcus simulans (both coagulase negative), were the most common cause of intramammary infection with a prevalence of 85.7% of the infected udder halves. The remaining 14.3% of the infection was due to Staphylococcus aureus. Bacteriology of bulk milk samples on the other hand, showed that raw milk obtained by the bucket system milking machine had the lowest total bacterial count (16,450 colony forming units (CFU)/ml) compared to that by pipeline milking machine (36,300 CFU/ml) or hand-milking (48,000 CFU/ml). No significant relationship was found between the somatic cell counts (SCC) and presence of bacterial infection in goat milk In comparison with the herds under the other 2 production systems, it was shown that dairy goat farming under the extensive production system, where hand-milking was used, can be adequate for the production of safe raw goat milk.     

Closure of the ductus arteriosus of indigenous South African goats at high altitude

The closure of the ductus arteriosus (DA) of 31 indigenous South African goats, whose ages ranged from 30 days prenatal to 60 days postnatal, were studied at an altitude of 1,514 m above sea level by vascular injection as well as histologically and ultrastructurally. The vascular injection results showed that functional occlusion started from the pulmonary end of the DA in kids 6 days old and progressed to the aortic end in kids 8 days old. Histologically, anatomical obliteration was observed in kids from 35 days of age. The functional closure was preceded by enlargement of the subendothelial region, progressive intimal thickening, presence of subendothelial vacuolization and endothelial detachment. There was radial orientation of the subintimal smooth muscle cells and subsequent migration towards the intima. The inner tunica media contained mast cells and areas of cytolysis. Following functional closure, the subendothelial region showed migrating subintimal smooth muscle cells with extensive cytoplasmic processes and, ultrastructurally a fragmented internal elastic lamina. In 15-day-old kids there were prominent, progressively enlarged cisternae of the rough endoplasmic reticulum and numerous free, dispersed ribosomes. In kids 19 and 25 days old, there was, additionally, rarefaction of the cell cytoplasm and appearance of intracellular myofibrils and extra cellular collagen in the surrounding amorphous matrix, which culminated in the complete anatomical closure of the DA in 35-day-old kids.     

Genetic diversity and population structure of South African smallholder farmer sheep breeds determined using the OvineSNP50 beadchip

Tropical Animal Health and Production - A population structure study was performed in South African ovine populations using the OvineSNP50 beadchip. Blood samples were obtained from 295 sheep of...     

Serum and tissue enzyme profiles of goats

Serum enzyme activities of sorbitol dehydrogenase, glutamate dehydrogenase, gamma glutamyltransferase, alkaline phosphatase, aspartic aminotransferase, and creatine kinase, were measured in five clinically normal mixed-breed goats. Tissue activities of these enzymes were also measured in two goats. These basal serum values were then used to determine the response to treatment with carbon tetrachloride (CCl4). The basal value for serum and hepatic tissue sorbitol dehydrogenase were appreciably greater for goats than previously reported for sheep and cattle. The change in the above serum enzymes after CCl4 treatment resembled that in sheep, but the amount of sorbitol dehydrogenase increase was less than that in sheep. This study established basal tissue and serum enzyme activity values and demonstrated the efficacy of the use of changes in serum S.D.H. and G.D.H. activity as indicators of acute hepatopathy in goats.     

Enzyme structure,enzyme function and allozyme diversity in mammals: trends from South African population genetic studies

In estimates of population genetic diversity based on allozyme heterozygosity, some enzymes are regularly more variable than others. Evolutionary theory suggests that functionally less important molecules, or parts of molecules, evolve more rapidly than more important ones; the latter enzymes should then theoretically be less polymorphic. In this paper I review most of the published papers on allozyme variability in southern African mammals, and correlate heterozygosity values with enzyme quaternary structure and the perceived importance of enzymes. Results provide support for the hypothesis of a linkage between enzyme quaternary structure and diversity. No association between enzyme function and heterogeneity was, however, observed.     

Preliminary comparison of different immune and production components in local and imported Saanen goats reared under a sub-tropical environment

Three objectives were included in this research work. The first objective compared different immune components in healthy mature males, mature females, and female kids of local and imported Saanen goats, reared under a sub-tropical environment. The significantly differing immune components were the blood monocyte percent, blood CD8 count, and the total white blood cell count. The second objective compared the performance of Saanen versus local does. The means of the milk yield and prolificacy of the imported Saanen does were significantly higher than those of the local does (p < 0.05). The third objective compared the immune responses (hemagglutination-HA titers) and complement fixation (CF) titers in mature does of the two breeds to chicken red blood cells (c-RBC). The HA titers showed a significant seroconversion only in imported Saanen (p < 0.05) but not in local does; however, the CF titers increased significantly at 4 weeks following priming with c-RBC in local (p < 0.05) but not in the imported Saanen does. The impact of the differences in blood immune components and responses to antigens in the compared goats on protection potential against prevalent diseases in the sub-tropical zone of the eastern Mediterranean countries is discussed.     

Growth performance and rumen development in Malabari kids reared under different production systems

Tropical Animal Health and Production - In order to investigate the effect of rearing systems on growth and rumen development in Malabari male kids, 14 pre-weaned Malabari male kids of uniform...     

Heterosis effects in a black and white dairy cattle population under different production environments

The effect of the environmental level of production (ENV) on the expression of heterosis for 305-day milk, fat, protein, and fat plus protein (FP) yields, lactation average somatic cell score (LSCS), and age at first calving (AFC) was investigated in first lactation Black and White dairy cows in the Netherlands, and officially enrolled in the Dutch herd-book. Holstein Friesian (HF), Dutch Friesian (DF), and first generation (F₁) crosses obtained from the mating of HF sires and DF dams (HD) were involved in the study, and data from animals with a calving date between 1990 and 2000 were used. A total of 22,930 cows with production and AFC information distributed in 3549 herds and 11,055 cows with LSCS information distributed in 2071 herds, were available. Adjusted lactation yield of milk for each herd was obtained using a model that accounted for fixed effects of herd, year and month of calving, genotype, and AFC. The overall mean of all adjusted data was computed, and 3 ENV were defined on the basis of the overall mean ± 0.5 standard deviations. Once ENV was defined, traits were analysed with a model that included fixed effects of ENV, herd nested within ENV, AFC (only production traits and LSCS), year and month of calving, genotype, and the interaction between ENV and genotype. Least squares means for the interaction effect were used to estimate heterosis and to evaluate its magnitude across ENV. Holstein Friesian achieved higher productions than DF. First generation crosses showed productions close to HF, especially in the low ENV. Estimates of heterosis for yield traits ranged from 2.4% (milk) in the high to 5.3% (fat) in the low ENV, and reduced with increasing ENV. Estimates for LSCS and AFC were low, with the exception of LSCS in the high ENV. Results suggest that the highest non-additive genetic effects for yield traits and LSCS were expressed in the most stressful ENV, i.e., the low one for production and the high one for LSCS.     

Relationship between aging and nutritionally controlled growth rate on heat production of heifers

The first objective of this study was to test how well a function that was developed to describe heat production (HP) in growing ewes fit HP data in growing heifers. The second objective was to determine the pattern of adaptation of HP to feed restriction and subsequent realimentation of nutrients. At 234.5 +/- 0.5 d of age, HP was determined by indirect calorimetry on 32 Meat Animal Research Center III heifers. Following the first calorimetry measurement, heifers on the High-High (HH) treatment continued to receive ad libitum access to feed, and daily feed offered to the Low-High (LH) heifers was set at 157 Mcal of ME/kg of BW0.75. Feed restriction of LH heifers continued for 84 d. After 84 d of restriction, LH heifers were allowed ad libitum access to feed. Heat production was determined 4 and 11 wk following feed restriction and 2, 5, 12, and 18 wk following realimentation. There was no residual bias when HP in ad libitum-fed heifers was estimated with an equation form developed in growing ewes: [(kcal/d) = f(BW, matBW) = BW (Ae[k(BW/mature BW)])], nor was there a residual bias when HP was predicted with an allometric equation: [(kcal/d) = f(BW) = A(BWk)]. However, there were residual biases when HP was estimated with an allometric equation that set the exponent to 0.75. Heat production per unit of BW of LH heifers was lower than that of HH heifers at 4 wk of feed restriction (P < 0.001), but HP did not differ between treatments at 11 wk of feed restriction (P = 0.87). At 2 (P = 0.002) and 5 wk (P < 0.001) following the increase in feed offered, HP per unit of BW of the LH heifers was greater than that of the HH heifers. Heat production did not differ between treatments at 12 and 18 wk following refeeding (P < 0.17). Our findings demonstrate that the relationship between HP and BW is described equally well by a logistic and allometric function, but applying a generalized interspecies exponent in an allometric equation to growing heifers results in a bias in estimating HP. The equation form developed in ewes can be used to develop a single equation for the prediction of HP across ages in heifers.     

Amphistome infection of goats farmed under resource-poor conditions in South Africa

From December 1998 to April 2000, a longitudinal study was conducted of the pooled trematode faecal egg counts of samples collected from goats of resource-poor farmers at Rust de Winter, Gauteng Province, Impendle, KwaZulu-Natal Province, and Kraaipan, North-West Province, South Africa. The amphistome faecal egg counts followed a seasonal pattem, with an increase in the counts during the warmer months of the year (October to March). This is the first work concerning the seasonal cycling of amphistomes in ruminants in South Africa.     

不同耕作措施旱地小麦生产应对气候变化的效应分析

为探索气候变化对小麦产量影响的机制和规律,在田间试验的基础上通过调试APSIM模型参数,并对模型进行检验,然后用APSIM模型模拟温度和CO₂浓度两因素七水平小麦产量,分析了3种耕作措施下小麦产量对温度和CO₂浓度的响应及敏感性强度。结果表明,不同耕作措施条件下,小麦产量随CO₂浓度升高呈二次抛物线上升型变化,但会出现报酬递减,且免耕覆盖的增产效应大于传统耕作和免耕2种耕作措施;小麦产量随温度升高呈二次抛物线型变化,其中传统耕作和免耕呈二次抛物线递减型变化,并呈叠加递减效应,而免耕覆盖呈二次抛物线拐点型变化,拐点值为0.94℃时,小麦产量可达到2 818.3 kg/hm²。温度和CO₂浓度互作对小麦产量的敏感性分不敏感、正敏感和负敏感区域,且免耕覆盖的敏感性变化较小。在3种耕作措施中,免耕覆盖CO₂浓度升高小麦的增产效应可以补偿高温所导致的减产,并且温度和CO₂浓度具有更好的协同促进作用。免耕覆盖小麦生产具有较好应对温度和CO₂浓度变化的能力,可以缓减气候变化带来的负效应。     

Relationship between aging and nutritionally controlled growth rate on heat production of ewe lambs

The hypothesis of this study is that ewes that have equal body weights, but differ in chronological age due to nutrient restriction, do not differ in metabolic rate. The objective of this study was to determine how reducing growth rate nutritionally alters the relationship between heat production per unit body weight and aging. Fasting heat production of 12 Dorset ewe lambs at 114 +/- 2 d of age was determined, and ewes were assigned to treatments. Treatments consisted of two different feeding levels of the same diet (ME = 2.5 Mcal/kg DM and 16.6% CP). The High treatment was offered 4.5% of their weekly BW per day, and the Low treatment was offered 2.5% of their weekly BW per day. Each treatment consisted of six animals that remained within treatment for the remainder of the study. Indirect-calorimetry measurements were repeated every 6 wk. Treatments differed in both the linear and quadratic term for fasted BW on age (P < 0.001). The rate of BW gain decreased as ewes aged in the High treatment, and the rate of BW gain increased as ewes aged in the Low treatment. The heat production:BW (HP:BW) ratio decreased in the High treatment as ewes aged and was described well by a previously reported prediction equation, but the ratio in the Low treatment was not described by this same equation. Describing the HP:BW ratio on age response with treatment-specific decay functions fit the data better than the pooled treatment function (P < 0.001). The HP:BW ratio decreased rapidly in the Low treatment following feed restriction, but remained elevated compared to the High treatment as animals aged. After excluding the initial measurements in the Low treatment that were taken before nutritional treatments were imposed, the HP:BW ratio was best described by a linear decrease. In conclusion, this study suggests that a previous model taking into account proportion of mature body size is a reasonable predictor for heat production across breeds of sheep growing in nutritionally adequate environments; however, it cannot be extended to sheep that are proportionally smaller in their mature BW due to nutritional restriction.     

Egg production and efficiency of food conversion of khaki campbell ducks under different management systems

1. Thirty‐two Khaki Campbell laying ducks were divided into two equal groups and housed either in floor pens or in cages in an environmentally controlled building. The food for two replicate groups of four birds each in each management system was rationed by weight and two other replicate groups were fed ad libitum. Housing and feeding treatment effects were assessed by measuring efficiency of food conversion into eggs and egg production.

2. Housing ducks in cages did not reduce egg production or efficiency of food conversion compared with the more conventional floor‐pen housing system. Egg production and egg size were adversely affected by the restricted feeding programme.

3. Caging in a controlled environment with unrestricted food appears to be a potentially feasible management system for laying ducks, comparable with such systems for laying fowls.     

Growth performance of fast-growing broilers reared under different types of production systems with outdoor access: Implications for organic and alternative production systems

Outdoor access is an important part of organic and free-range poultry production, yet limited information exists on the effect of various housing and production systems on growth performance and colonization of food-borne pathogens. Therefore, the primary purpose of the current study was to evaluate the influence of different housing systems, particularly fixed versus small, portable houses, with and without outdoor access to pasture, on seasonal growth performance, leg quality, and presence of bacterial food-borne pathogens. In the current study, we used fast-growing broilers, as many small producers use commercial broilers due to their carcass conformation and high breast yield compared with slow-growing hybrids or standard heritage breeds. Although interest in alternative genetics exists because they may be more adapted to outdoor production, they require longer growing periods, with accompanying labor and cost. A pasture containing a mixture of forages was used to simulate the conditions common for small farms in the local region. The experiment had 4 treatment groups: (1) small, portable hoop houses with access to pasture, (2) small, portable hoop houses without access to pasture, (3) a fixed house with access to the outdoors, and (4) a fixed house without access to the outdoors. The present study was repeated at different times of the year to determine if a seasonal effect on the consumption of pasture and carcass quality was present. Overall, raising birds in hoop houses resulted in a reduced growth rate compared with birds raised in the fixed house. None of the production systems altered bone strength or feed conversion. Food-borne pathogens commonly associated with poultry were not found in any of the environments tested. Seasonal production was an issue in the small hoop house birds, as extreme heat in the summer resulted in early termination of that trial. Expanding on forage choice in pastures and customizing hoop houses to deal with weather fluctuations, especially in regions where extreme heat may affect production, are important considerations for these systems.