农牧交错区不同牧草时期放牧奶牛采食量与食性的研究

用饱和烷烃法对不同牧草时期放牧奶牛的采食量进行了测定.结果表明:放牧奶牛在牧草幼嫩期、旺盛期、枯黄期3期的采食量结果分别为:绝对采食量(kg/d)为11.54±0.66、13.83±0.55、5.75±0.32,采食量在牧草旺盛期时达到最高.采食组成幼嫩期以苔草为主、旺盛期以隐子草为主、枯黄期以赖草为主,这与草场植物的生长和奶牛的喜好有关.     

The Relationship Between Post‐Thaw Sperm DNA Integrity and Non‐Return Rate Among Norwegian Cross‐Bred Rams

With the aim of investigating the relationship between sperm DNA integrity and non‐return rate (NRR) among Norwegian cross‐bred rams, semen from 15 individuals was examined by flow cytometry. Sperm Chromatin Structure Assay (SCSA) quantifies the proportion of spermatozoa with denatured DNA after in situ acid treatment, and the four parameters % DFI, % HDS, MEAN DFI and SD DFI are all different measures of DNA denaturation and maturation. Field fertility, reported as NRR 25 days after insemination was based on all inseminations from a large‐scale breeding programme and supplied by the Norwegian Association of Sheep and Goat Farmers. From each ram, four straws from four different weeks of the breeding season were analysed, and the associations between 25‐day NRR and the mean of the four SCSA parameters were tested using a logistic regression model. The results revealed no association between fertility and % DFI or % HDS, while SD DFI and MEAN DFI showed a significant negative association with NRR. Further, the SCSA values varied significantly between ejaculates within ram among some of the rams in the study. However, no significant association was seen between these intra‐individual differences in sperm DNA integrity and NRR. In conclusion, this study suggests an association between sperm DNA integrity and NRR for rams. However, further research must be conducted to confirm these findings and determine whether sperm DNA assessments can be applied to predict ram fertility.     

Effect of Sward Height on Pasture Nonstructural Carbohydrate Concentrations and Blood Glucose/Insulin Profiles in Grazing Horses

Six mature stock-type geldings with maintenance only requirements were used in a randomized cross-over design to determine the effect of sward height on pasture plant nonstructural carbohydrate (NSC) concentrations and blood glucose and insulin concentrations. Horses were randomly assigned to one of two tall fescue (Lolium arundinaceum Schreb cv Max-Q, Pennington Seed, Madison, GA) grazing cells (0.37 ha) having two different sward heights for a period of 7 days: (1) short (approximately 15 cm; n = 3) or tall (between 30 and 40 cm; n = 3). After the first 7-day period, treatment groups were reversed by moving horses to ungrazed cells having similar characteristics to those used in the first 7 days, so that all horses receive all treatments resulting in six observations per treatment. Both short and tall grazing cells were mowed to a height of approximately 15 cm 32 days before the experiment starts. The short grazing cells were removed to approximately 15 cm at 11 days before the start of the first 7-day period and again 1 day before the start of each 7-day period. All horses had access to pasture for 10 h/d beginning at 8 AM and ending at 6 PM. Although not at pasture, all horses were individually housed in 3.7 × 12.2 m partially covered pens containing automatic water troughs and a crushed stone surface. Herbage mass (kg DM/ha) was determined by use of a falling plate meter for each pasture to ensure that both groups of horses had adequate dry matter to provide grazing for at least 7 days. On day 7 of each period, jugular venous blood samples were collected from each horse before being turned out to pasture, and then at 2, 4, 6, and 8 hours after turn-out. Pasture samples were also collected from each grazing cell at the same time blood samples were taken. Serum and plasma from blood samples were harvested and analyzed for insulin and glucose concentrations, respectively. Pasture samples were analyzed for water soluble carbohydrate (WSC), ethanol soluble carbohydrate (ESC), and starch. The sum of WSC and starch were used as an estimate of NSC. Area under the curve (AUC) and peak concentration were calculated for both plasma glucose (PPG) and serum insulin (PSI) concentration and were analyzed using analysis of variance for randomized cross-over designs. Pasture WSC, ESC, starch, and NSC concentrations were analyzed using analysis of variance for randomized complete block design. A P value of < .05 was considered significant. Mean pasture plant NSC, WSC, and ESC concentrations were lower (P < .001) in short as compared with tall. Pasture plant starch concentration was not different between treatments. Mean pregrazing plasma glucose concentrations, PPG concentrations, and plasma glucose AUC were not affected by treatment. Mean pregrazing serum insulin concentrations were not affected by treatment. Mean PSI and insulin AUC were greater (P < .01) when horses grazed tall, as compared with short. In conclusion, decreasing the sward height by mowing pasture decreased NSC, WSC, and ESC concentrations and subsequently decreased the postprandial insulin response of horses grazing the pasture. These findings may be important in developing strategies aimed at preventing insulin resistance in grazing horses.     

Association of Season and Pasture Grazing with Blood Hormone and Metabolite Concentrations in Horses with Presumed Pituitary Pars Intermedia Dysfunction

Background: Pituitary pars intermedia dysfunction (PPID) is a risk factor for pasture‐associated laminitis, which follows a seasonal pattern. Hypothesis: Hormonal responses to season differ between PPID and unaffected horses. Animals: Seventeen horses aged 8–30 years (14 horses ≥ 20 years of age). Methods: Longitudinal observational study. Blood was collected monthly from August 2007 until July 2008 after pasture grazing and again after overnight stall confinement. Blood hormone and metabolite concentrations were measured and pasture grass samples were analyzed to determine carbohydrate content. Analysis of variance analysis for repeated measures was performed. Results: Mean ACTH concentrations varied significantly over time (P < .001), with higher concentrations detected in August, September, and October compared with November–April. Pasture × time effects were detected for glucose and insulin concentrations, with peaks observed in September. Horses were retrospectively allocated to PPID (n = 8) and control (n = 9) groups on the basis of plasma ACTH concentrations. Changes in insulin concentrations over time differed in the PPID group when compared with the control group. Insulin concentrations were positively correlated with grass carbohydrate composition. Conclusions and Clinical Importance: PPID did not affect the timing or duration of the seasonal increase in ACTH concentrations, but higher values were detected in affected horses. Insulin concentrations differed between groups, but hyperinsulinemia was rarely detected. Glucose and insulin concentrations peaked in September when horses were grazing on pasture, which could be relevant to the seasonal pattern of laminitis.     

Effects of Feeding Dry Glycerol to Primiparous Holstein Dairy Cows on Follicular Development,Reproductive Performance and Metabolic Parameters Related to Fertility during the Early Post‐partum Period

This study examined the effects of dry glycerol supplementation on follicular growth, post‐partum interval to first ovulation, concentration of serum metabolites and hormones related to fertility, body condition score (BCS) and body weight (BW) in primiparous Holstein dairy cows. Sixty primiparous Holstein dairy cows were randomly assigned to two groups (control: n = 30 and glycerol supplemented: n = 30). Dry glycerol (250 g/day/cow) was fed as a top dressing to the common lactating total mixed ration (TMR) from parturition to 21 days post‐partum. Ovaries were examined four times using ultrasonography on days 13, 19, 25 and 36 post‐partum to determine ovarian follicular growth. Concentration of serum metabolites and hormones was determined weekly. Body condition score was evaluated weekly from weeks 1 to 5 after parturition, and BWs were recorded three times on days 1, 11 and 21 during the experimental period. The cows fed dry glycerol had more large follicles (p < 0.0001) and corpora lutea (CL) (p = 0.02) compared with the control cows. Days to the first ovulation (p = 0.06), days to first oestrus (p = 0.05), services per conception (p = 0.06) and days open (p = 0.004) were positively affected by dry glycerol supplementation. Serum concentration of glucose and insulin was higher in dry glycerol‐supplemented cows (p = 0.1; p = 0.06, respectively). Feeding glycerol had no effect on mean serum concentrations of β‐hydroxybutyrate, non‐esterified fatty acids and IGF‐1 during the experimental period. However, significant differences were observed at concentration of BHBA and IGF‐1 (p = 0.02 and p = 0.04, respectively) between two groups on day 21 after calving. The cows in the glycerol‐fed group had higher serum progesterone concentrations on days 33 (p = 0.007) and 36 (p = 0.004) after calving. Supplemented cows had lower body condition loss during weeks 1–5 after calving compared with the control cows (0.34 vs 0.41 BCS). In week 13 post‐partum, the proportion of cycling cows was 83.3 and 69.9% for those which received supplemented or non‐supplemented diet, respectively. These results demonstrated that feeding dry glycerol as a glucogenic supply may be useful to improve negative energy balance and reproductive efficiency in young cows which calve with high requirement of energy.     

The Comparison of Antioxidative/Oxidative Profile in Colostrum,Milk and Blood of Early Post‐Partum Cows During their First and Second Lactation

The aim of the study was to compare antioxidative/oxidative profile in blood, colostrum and milk of early post‐partum cows during their first and second lactation. A total of 19 healthy, primiparous cows were included in experiment and samples were collected during 2 years from the same animals immediately after parturition, 24, 48 h as well as 6 and 12 days later. All parameters including the activity of glutathione peroxidase (GSH‐Px), total antioxidant capacity (TAC), the content of vitamin A, C as well as the contents of products of lipid and protein peroxidation were determined by the use of spectrophotometric methods. Comparing the profile within lactation, TAC and GSH‐Px activity in blood showed decreasing trends, while parameters of lipid and protein peroxidation fluctuated. All examined parameters in colostrum and milk except from intermediates of lipid peroxidation exhibited increasing trends. These results which showed dynamic changes of antioxidative/oxidative profile not only in blood but also in colostrum/milk within examined period of time suggested appropriate answer of organism to current challenge. Moreover, not uniform but detectable changes between first and second lactation suggested that two consecutive lactations are not the same. Comparing first and second lactation, TAC and parameters of lipid and protein peroxidation in blood showed increasing tendency in second as first lactation while GSH‐Px activity was opposite. The content of antioxidative vitamins and SH groups in colostrum/milk showed increasing tendency in second as first lactation, while TAC and content of end products of lipid peroxidation showed opposite trend, and GSH‐Px together with intermediates of lipid peroxidation remained stable. Molecular and biochemical background for it require further elucidation.     

泌乳早期奶牛的饲养与保健

本文结合笔者多年的实践经验,对奶牛泌乳早期的饲养、挤奶方法、兽医保健、繁育保健等几个方面加以总结,供广大养殖户参考。     

Pre‐ and Post‐Partum Mild Underfeeding Influences Gene Expression in the Reproductive Tract of Cyclic Dairy Cows

Undernutrition before and after calving has a detrimental effect on the fertility of dairy cows. The effect of nutritional stress was previously reported to influence gene expression in key tissues for metabolic health and reproduction such as the liver and the genital tract early after calving, but not at breeding, that is, between 70 and 90 days post‐partum. This study investigated the effects of pre‐ and post‐partum mild underfeeding on global gene expression in the oviduct, endometrium and corpus luteum of eight multiparous Holstein cows during the early and middle phases of an induced cycle 80 days post‐partum. Four control cows received 100% of energy and protein requirements during the dry period and after calving, while four underfed received 80% of control diet. Oestrous synchronization treatment was used to induce ovulation on D80 post‐partum. Oviducts, ovaries and the anterior part of each uterine horn were recovered surgically 4, 8, 12 and 15 days after ovulation. Corpora lutea were dissected from the ovaries, and the endometrium was separated from the stroma and myometrium in each uterine horn. The oviduct segments were comprised of ampulla and isthmus. RNAs from ipsi‐ and contralateral samples were pooled on an equal weight basis. In each tissue, gene expression was assessed on a custom bovine 10K array. No differentially expressed gene (DEG) in the corpus luteum was identified between underfed and control, conversely to 293 DEGs in the oviduct vs 1 in the endometrium under a false discovery rate (FDR) < 0.10 and 1370 DEGs vs 3, respectively, under FDR < 0.15. Additionally, we used dedicated statistics (regularized canonical correlation analysis) to correlate the post‐partum patterns of six plasma metabolites and hormones related to energy metabolism measured weekly between calving and D80 with gene expression. High correlations were observed between post‐partum patterns of IGF‐1, insulin, β‐hydroxybutyrate and the expression in the oviduct of genes related to reproductive system disease, connective tissue disorders and metabolic disease. Moreover, we found special interest in the literature to retinoic acid‐related genes (e.g. FABP5/CRABP2) that might indicate abnormalities in post‐partum tissue repair mechanisms. In conclusion, this experiment highlights relationships between underfeeding and gene expression in the oviduct and endometrium after ovulation in cyclic Holstein cows. This might help to explain the effect of mild undernutrition on fertilization failure and early embryonic mortality in post‐partum dairy cows.     

The Distribution of Gastrin,Somatostatin and Glucagon Immunoreactive (IR) Cells in Ostrich Stomach During the Pre‐ and Post‐hatching Period

Peptides of the gastrointestinal tract play a significant role in the digestive processes and the development of the body; therefore, it is important to have an understanding of location and distribution of gastrin, somatostatin and glucagon immunoreactive (IR) cells in the stomach mucosa of growing birds. For this purpose, 6 embryos and 37 chicks from an ostrich farm in Latvia were used. Tissue samples were collected from the proventriculus – superficial and deep glandular region and from the ventriculus – side wall and pyloric region. The number of cells was determined in 10 mucosal fields of each tissue sample. For statistical analysis, the one‐way anova method was used. Gastrin IR cells regarding the stomach mucosa were found only in the pyloric region. Somatostatin IR cells were most densely located in the pyloric region too, but some cells were also discovered in the mucosa of proventriculus and ventriculus. Glucagon IR cells were found in the epithelium of the deep glands of the proventriculus and only some cells of the superficial glands of the proventriculus, and the ventriculus side wall mucosa. Gastrin and somatostatin IR cells were present in a comparatively large quantity in the ostrich chicks' ventriculus – pyloric region yet not long before hatching. They were located deep in the mucosa of pyloric glands, and their number tended to increase with birds advancing in age.     

Distribution and Characterisation of Goblet Cells in the Large Intestine of Ostriches during the Pre‐ and Post‐Hatch Period

The role of goblet cell secretion, containing mucopolysaccharides, in the formation of a protective barrier of intestinal mucosa and transportation of the intestinal content has been described quite extensively. However, information on the quality composition of mucopolysaccharides and its changes in the intestinal tract of ostrich chicks, especially in the large intestinal segments, is unavailable. In the current study, ostrich embryos/chicks (n = 6/36) of both sexes were used shortly before hatching and during the first months of the post‐hatch period. Tissues for histology were taken from the large intestine: the medium segments of the caecum, proximal and distal parts of colon. By using histochemical reactions, the differentiation of goblet cells as well as chemical composition of mucopolysaccharides was carried out. The cells contained acid (AB+), neutral (PAS+) and mixed (AB/PAS+) mucopolysaccharides. The number of goblet cells in the large intestine per unit area of mucosa increased towards the cloaca, and it was the highest in the distal part of the colon. The qualitative goblet cell composition in different large intestinal parts was different in all ages. In the caecum, goblet cells containing acid and mixed mucopolysaccharides dominate post‐hatch, whereas in the colon, goblet cells containing acid mucopolysaccharides predominated. The most rapid changes in the qualitative goblet cell composition occur during the first week post‐hatch when in all the intestinal segments the proportion of cells containing acid mucopolysaccharides continuously increased.     

Effect of β‐Carotene Supply During Close‐up Dry Period on the Onset of First Postpartum Luteal Activity in Dairy Cows

The aim of this study was to examine the effect of β‐carotene supply during the close‐up dry period on the onset of first postpartum luteal activity in dairy cows. Twelve cows were supplied with 2000 mg of β‐carotene (20 g Rovimix^®β‐Carotene containing 10%β‐carotene; DSM Nutrition Japan K.K., Tokyo, Japan) by oral administration daily from day 21 before expected calving date to parturition. Fourteen cows (control) did not receive β‐carotene supplementation. Blood samples were obtained on days 21, 14 and 7 before expected calving date and on days 1, 7, 14, 21 postpartum. When the plasma progesterone concentration exceeded 1 ng/ml by day 21 postpartum, luteal activity was assumed to have been initiated. The result showed that serum β‐carotene concentrations in the β‐carotene cows were higher than in the control cows during the experimental period (p < 0.01). The number of cows with the onset of luteal activity by day 21 postpartum was 9/12 in the β‐carotene cows and 4/14 in the control cows (p < 0.05). Retinol, certain metabolic parameters and metabolic hormones concentrations did not differ between β‐carotene and control cows. In addition, serum retinol concentration in β‐carotene cows without luteal activity was lower than in β‐carotene cows with luteal activity (p < 0.05), and serum gamma‐glutamyl transpeptidase concentration in β‐carotene cows with luteal activity (p < 0.05) and control cows without luteal activity (p < 0.01) was higher than in control cows with luteal activity. In conclusion, β‐carotene supply during the close‐up dry period may support the onset of luteal activity during early lactation in dairy cows.     

Apoptosis‐Related Protein Expression During Pre‐ and Post‐Natal Testicular Development After Administration of Glucocorticoid in utero in the Sheep

Pre‐natal glucocorticoids are used in women at risk of preterm delivery to induce foetal lung maturation. However, glucocorticoids can produce negative outcomes for other tissues such as the reproductive system. We therefore tested the effects of pre‐natal betamethasone on testicular morphology and apoptotic protein immune expression during pre‐ and post‐natal development. Pregnant ewes (n = 42) bearing singleton male foetuses were randomly allocated to receive intramuscular injections of saline or betamethasone (0. 5 mg/kg) at 104, 111 and 118 days of gestation (DG). Testes were collected at 121 and 132 DG, and at 45 and 90 post‐natal days (PD) and subjected to morphometric analysis (volume densities of sex cords and interstitial tissues; sex cord diameter). Immunohistochemistry (% stained area) was used to assess active caspase‐3, Bax, Bcl‐2 and cell‐cycle proteins (PCNA). Compared with control values, betamethasone treatment decreased sex cord diameter at 121 DG, 45 and 90 PD, and sex cord volume at 90 PD. Active caspase‐3 was decreased by betamethasone at 121 DG and 90 PD, but Bax was increased in all betamethasone groups. Bcl‐2 and PCNA decreased in the betamethasone groups at 121 DG and 45 PD, but increased at 132 DG and 90 PD. We conclude that high levels of pre‐natally administered glucocorticoid reduce foetal testicular development, perhaps via changes in the balance between pro‐ and anti‐apoptotic proteins and cell‐cycle proteins. These outcomes could compromise the future spermatogenic potential of male offspring.     

Pregnancy‐Induced ISG‐15 and MX‐1 Gene Expression is Detected in the Liver of Holstein–Friesian Heifers During Late Peri‐Implantation Period

The bovine embryonic signal interferon‐τ (IFN‐τ) produced by the trophoblast is known to pass through the uterine fluid towards the endometrium and further into the maternal blood, where IFN‐τ induces specific expression of interferon‐stimulated gene expression (ISG), for example in peripheral leucocytes. In sheep, it was shown experimentally by administration of IFN‐τ that ISG is also detectable in the liver. The objective was to test whether ISG can be detected in liver biopsy specimens from Holstein–Friesian heifers during early pregnancy. Liver biopsies were taken on day 18 from pregnant and non‐pregnant heifers (n = 19), and the interferon‐stimulated protein 15 kDa (ISG‐15) and myxovirus‐resistance protein‐1 (MX‐1) gene expression was detected. The expression of both MX‐1 (p: 24.33 ± 7.40 vs np: 9.00 ± 4.02) and ISG‐15 (p: 43.73 ± 23.22 vs 7.83 ± 3.63) was higher in pregnant compared to non‐pregnant heifers (p < 0.05). In conclusion, pregnancy induced ISG‐15 and MX‐1 gene expression in the liver already at day 18 in cattle.     

First Service Pregnancy Rates Following Post‐AI Use of hCG in Ovsynch and Heatsynch Programmes in Lactating Dairy Cows

Lactating dairy cows (n = 667) at random stages of the oestrous cycle were assigned to either ovsynch (O, n = 228), heatsynch (H, n = 252) or control (C, n = 187) groups. Cows in O and H groups received 100 μg of GnRH agonist, i.m. (day 0) starting at 44 ± 3 days in milk (DIM), and 500 μg of cloprostenol, i.m. (day 7). In O group, cows received 100 μg of GnRH (day 9) and were artificially inseminated without oestrus detection 16–20 h later. In H group, cows received 1 mg oestradiol benzoate (EB) i.m., 24 h after the cloprostenol injection and were artificially inseminated without oestrus detection 48–52 h after the EB injection. Cows in C group were inseminated at natural oestrus. On the day of artificial insemination (AI), cows in all groups were assigned to subgroups as follows: human Chorionic Gonadotrophin (O‐hCG) (n = 112), O‐saline (n = 116), H‐hCG (n = 123), H‐saline (n = 129), C‐hCG (n = 94) and C‐saline (n = 93) subgroups. Cows in hCG and saline subgroups received 3000 IU hCG i.m. and or 10 ml saline at day 5 post‐AI (day 15), respectively. Pregnancy status was assessed by palpation per rectum at days 40 to 45 after AI. The logistic regression model using just main effects of season (summer and winter), parity (primiparous and pluriparous), method₁ (O, H and C) and method₂ (hCG and saline) showed that all factors, except method₁, were significant. Significant effects of season (p < 0.01), hCG and parity (p < 0.01), and a trend of parity and season (p < 0.1) were detected. A clear negative effect of warm period on first service pregnancy rate was noted (p < 0.01). The pregnancy rate was the lowest in the H protocol during warm period (p < 0.05). Treatment with hCG 5 days after AI significantly improved pregnancy rates in those cows that were treated with the H protocol compared with saline treatments (41.5% vs 24.8%; p < 0.01). O and H were more effective in primiparous than in pluriparous cows (46.1% vs 29.9%; p < 0.1 and 43.6% vs 24.6%; p < 0.01). First service pregnancy rates were higher in primiparous hCG‐treated than in pluriparous hCG‐treated cows (57.9% vs 32.3%; p < 0.01). The pregnancy rate was higher for the hCG‐treated cows compared with saline‐treated cows during warm period (37.9% vs 23.6%; p < 0.001).     

Therapeutic Approaches to Pregnancy Loss of Non‐infectious Cause During the Late Embryonic/Early Foetal Period in Dairy Cattle. A Review

The problem of pregnancy loss during the late embryonic/early foetal period due to non‐infectious causes in dairy cattle is on the rise, especially in high milk producing cows. This review discusses recent therapeutic approaches designed to reduce the incidence of early foetal loss. These strategies are based on the fact that low plasma concentrations of progesterone are commonly related to foetal loss. Progesterone supplementation during the late embryonic/early foetal period has proven useful in curtailing losses, mainly in single pregnancies, whereas a more positive effect of treatment with GnRH than progesterone has been found in twin pregnancies. Therapeutics is not necessary in cows with an additional corpus luteum. In practical terms, suggestions include recording the number of embryos and corpora lutea on first pregnancy diagnosis and checking for normal pregnancy progression on day 60 post‐insemination.     

产蛋期母鸡血液激素的昼夜变化

用放射免疫方法检测了10只200日龄产蛋期母鸡血液激素的昼夜变化。结果:血浆雌二醇含量在11时出现一次峰值,孕酮在8时和17时出现两次峰值,黄体生成素在17时出现一次峰值,其他时间这几种激素的含量均波动不大;甲状腺素含量在一昼夜内一直较稳定,无明显波动。此外,对上述血液激素与排卵的关系作了讨论。     

拉萨河谷冬春季放牧与舍饲彭波半细毛羊牧草、血液及被毛矿物质含量

为分析拉萨河谷冬春季放牧与舍饲彭波半细毛羊采食牧草、血液及被毛中主要矿物质元素的含量,试验选用1.5岁左右彭波半细毛羊母羊60只,随机分为放牧组(GZ)和舍饲组(IF)进行试验。结果表明:试验所用牧草矿物质元素,除钼外其他元素含量均为绿麦草>冬季天然牧草。冬季天然牧草磷、镁、硫、铜、锰、锌和硒及绿麦草镁含量低于正常范围。(2)舍饲组血清钙(P=0.026)、硫(P=0.030)、铜(P=0.011)和钼(P=0.014)含量高于放牧组,镁(P=0.090)、铁(P=0.071)、锌(P=0.083)和碘(P=0.066)含量有增高的趋势;其被毛钙(P=0.003)、磷(P=0.006)、镁(P<0.001)、铁(P=0.022)、锰(P<0.001)和碘(P=0.012)含量均高于后者,铜含量有增高的趋势(P=0.068)。在血液和被毛中,放牧组血清铜、锰及被毛铜、锰和硒含量及舍饲组血锰及被毛锰、硒含量均低于推荐值。以上结果表明,拉萨河谷冬春季放牧彭波半细毛羊钙、铁、钼和碘充足,但磷、镁、硫、铜、锰、锌和硒缺乏或不足;舍饲(以谷物为主的精补料+绿麦草干草)能有效解决磷、镁、硫、铜、锌和硒的缺乏问题,但锰仍需补充。     

Corpus luteum Function and Pregnancy Outcome in Buffaloes during the Transition Period from Breeding to Non‐Breeding Season

The aim in this study was to investigate corpus luteum function and embryonic loss in buffaloes mated by artificial inseminations (AI) during the transitional period from breeding to non‐breeding season. The study was carried out using 288 multiparous Italian Mediterranean Buffalo cows at 110 ± 4 days in milk. The buffaloes were mated by AI after synchronization of ovulation by the Ovsynch‐TAI protocol 25 days after AI buffaloes underwent trans‐rectal ultrasonography to assess embryonic development. Pregnancy diagnosis was confirmed on Days 45 and 70 after AI by rectal palpation. Buffaloes pregnant on Day 25 but not on Day 45 were considered to have undergone late embryonic mortality (LEM), whilst buffaloes pregnant on Day 45 but not on Day 70 were considered to have undergone foetal mortality (FM). Corpus luteum size and blood flow were determined by real‐time B‐mode/colour‐Doppler on day 10 after AI in 122 buffaloes. The resistive index (RI) and pulsatility index (PI) were recorded at the time. Milk samples were collected on Days 10, 20 and 25 after AI in all inseminated buffaloes for the assay of whey P4 concentrations. Data were analysed by anova . Pregnancy rate on Day 25 after AI was 48.6% (140/288) and declined to 35.4% (102/288) and 30.6% (88/288) by Day 45 and Day 70 respectively. The incidences of LEM and FM were respectively 27.1% (38/140) and 13.7% (14/102). Pregnant buffaloes had greater (p < 0.01) whey concentrations of P4 from Day 20 onwards than buffaloes which showed LEM, whilst P4 in buffaloes that showed FM did not differ from the other two groups on Day 10 and Day 20. Corpus luteum blood flow on Day 10 after AI showed higher RI (p < 0.05) and PI (p = 0.07) values in buffaloes that subsequently were not pregnant on Day 25 compared with pregnant buffaloes. Buffaloes that were not pregnant on Day 45 also had a higher (p = 0.02) RI value on Day 10 than pregnant buffaloes, whilst PI values on Day 10 did not differ for the two groups of buffaloes. It was concluded that blood flow to the corpus luteum on Day 10 after AI influences corpus luteum function as judged by P4 secretion and also embryonic development and attachment in buffaloes.