Ovarian follicular responses in dairy cows treated with GnRH and cloprostenol

Lactating, nonpregnant (with a corpus luteum) Holsteins were given 100 ug GnRH (n = 12) or saline (n = 12) and 500 ug cloprostenol 6 d later. Following luteolysis, ovulation occurred 10.1 +/- 0.2 d (range, 9-12 d) after GnRH and 8.6 +/- 1.0 d (range, 3-12 d) after saline (differences between groups: means, P > 0.05; variability, P < 0.001). Treatment with GnRH and cloprostenol resulted in a relatively synchronous ovulation.     

不同青饲料饲喂泌乳奶牛试验

试验选择年龄、胎次、体重、体况、产奶量相近的奶牛20头，随机分为4组（即对照Ⅳ组、试验Ⅰ、Ⅱ、Ⅲ组），每组5头，进行为期40d的饲养试验，其中包括lOd的预试期。试验Ⅰ、Ⅱ、Ⅲ组的饲料配方是在对照Ⅳ组的基础上，分别用WL－323紫花苜蓿、普那菊苣和特高黑麦草替代野青草。试验结果表明：几种牧草均能显著提高泌乳奶牛的产奶性能，其中WL－323紫花苜蓿、普那菊苣显著优于特高黑麦草，特高黑麦草显著优于野青草。Ⅰ－Ⅳ组的牛奶饲料成本差异显著，分别为0．83元/kg、0．84元/kg、0．87元/kg、0．93／kg。     

The effect of season on reproduction in dairy cattle

A survey was carried out in North West Tasmania to compare the breeding performance of 2,068 cows in 27 dairy herds--15 herds calving in spring and 12 in autumn. The percentage of cows submitted to artificial insemination for the first time in the first 24 days of the mating period was 87% for the spring calving group and 75% for the autumn calving group. Figures for non-return-to-service rate over the subsequent 21 days were 72% and 55%, respectively. The difference in breeding performance associated with time of calving was not attributable to age, calving to mating interval or on cow condition or daily milk fat yield at 3 weeks (+/- 1 week) after the start of mating.     

The effect of estradiol cypionate (ECP) on ovarian follicular development and ovulation in dairy cattle.

The efficacy of estradiol cypionate (ECP) for synchronizing ovarian follicular development was determined in lactating Holstein-Friesian cattle. In Experiment 1, 13 cattle were given simultaneous intramuscular (i.m.) injections of 100 mg progesterone and 0 (control), 0.5 or 1.0 mg ECP on Day 3, after a synchronized ovulation (Day 0). Maximum diameter of the dominant follicle of Wave 1 was significantly larger in control cattle than in those given 0.5 or 1.0 mg ECP (means: 15.7, 13.2, and 12.9 mm, respectively). Mean day of emergence of Wave 2 was significantly later in controls than in those given 1.0 mg ECP, with the 0.5 mg group intermediate (Days 10.2, 8.8 and 9.5, respectively). In Experiment 2, 14 cattle were given a CIDR-B and IM injections of 1 mg ECP and 50 mg progesterone without regard to stage of cycle (treatment = Day 0). On Day 8, the CIDR-B was removed and 500 micrograms cloprostenol injected, IM. Mean days of wave emergence (Day 3.4; range: -2 to 7) and ovulation (Day 12.1; range: 10 to 14) indicated that ECP had limited efficacy for synchronizing follicular development and ovulation in dairy cattle when given at random stages of the estrous cycle.     

Effect of synchronization of follicle-wave emergence with estradiol and progesterone and superstimulation with follicle-stimulating hormone on milk estrogen concentrations in dairy cattle

Very little is known about the effects of hormonal synchronization of follicle waves and superovulation on the estrogen content of a cow’s milk. The objective of this study was to determine the effect in dairy cows of synchronization with estradiol-17β (E2) and progesterone (P4) on milk E2 concentrations and to compare these levels with those achieved during superstimulation for 4 d with porcine follicle-stimulating hormone (FSH). The milk E2 concentrations were raised significantly above pretreatment levels (P < 0.05) for 2 d after synchronization, the mean peak being 40.2 ± 18.5 (standard error) pg/mL and the pretreatment mean 1.5 ± 0.5 pg/mL. The mean peak E2 concentration during ovarian stimulation was 4.4 ± 0.7 pg/mL. The mean E2 concentration was significantly higher (P < 0.05) after synchronization than during superstimulation for the 1st milking after synchronization but not subsequent milkings. The milk estrone concentrations were above pretreatment levels for 1 d after synchronization and were not different from those observed during superstimulation.     

The effect of repeated follicular puncture on ovarian function in dairy heifers

Three dairy heifers were examined during three consecutive oestrous cycles (control period, CP). Subsequently, the animals were subjected to 4 and then 5 weeks of twice-weekly ovum pick-up (OPU) (FPP1 and FPP2, respectively) with a recovery period (RP) of two consecutive oestrous cycles between FPP1 and FPP2. After FPP2, the animals were slaughtered and the ovaries were macroscopically examined. Throughout, ovarian activity was monitored by transrectal ultrasonography and concentrations of plasma progesterone. During CP, all the heifers showed normal cyclicity. During FPPs, the heifers occasionally presented oestrous activity. Corpus luteum (CL)-like structures developed from punctured follicles with diameters and life-spans varying from smaller and shorter than those in the CP (P > 0.05) to equal to those in the CP. There was a tendency for a lower number of emerging and punctured follicles in the presence of a CL-like structure. Subsequently to FPP1, all heifers regained normal cyclicity. A thickening of the ovarian tunica albuginea and a slight hardening of the ovaries were found postmortem. In conclusion, dairy heifers can occasionally show cyclic activity and form CL-like structures during twice-weekly OPU. Further, OPU did not seem to cause any major negative effects on ovarian structure and subsequent ovarian function.     

The effect of intra-ruminal selenium pellets on growth rate,lactation and reproductive efficiency in dairy cattle

In each of two dairy herds (A and B), rising yearling heifers (Trial 1) and adult cows (Trial 2) were assigned to three treatment groups. Untreated animals were compared to animals treated with either two or four intra-ruminal pellets containing 3 g of elemental selenium. The administration of pellets at the recommended dose (two pellets per animal) was effective in elevating whole blood glutathione peroxidase activity and selenium concentration to over 10 times those of control animals.

In Trial 1, a 15% response in liveweight gain (p<0.001) occurred in yearling heifers in the herd with the lowest pre-treatment selenium status. In Trial 2, cows receiving two pellets produced a greater milk volume (p=0.06) and more milk solids (p=0.02) than untreated controls; an increase in volume of 5.4% and 8%, and in milk solids of 6.5% and 6.4%) were noted in herds A and B respectively. There was a trend toyards decreasing somatic cell counts in milk from the treated cows when compared to controls, the four-pellet group in Herd A and the two-pellet group in Herd B being significantly different from their respective control group. No between-group differences were noted in calving-first service or calving-conception intervals, nor in the proportion of animals pregnant to first or all services. The administration of selenium at twice the recommended dose rate yielded no additional response above that noted after the administration of the recommended dose. The results of this study support the use of currently recommended Ministry of Agriculture and Fisheries selenium reference ranges in cattle for the prediction of a response to supplementation.     

An evaluation of simultaneous GnRH and cloprostenol treatment of dairy cattle with cystic ovaries

In a randomized double-blind clinical trial, 75 cows with ovarian cysts were treated with the synthetic gonadotropin releasing hormone, gonadorelin acetate (GnRH). Forty-two of these cows were simultaneously treated with cloprostenol (CP), and the remaining 33 cows received sterile saline. Milk progesterone (P₄) was measured at treatment and two days later. Clinical response 30 days after treatment was determined by palpation per rectum, and estrus and breeding dates were recorded up to 90 days after treatment. Cows were examined for pregnancy by palpation per rectum 40 days or more after breeding. Milk progesterone levels two days after treatment were significantly lower and the 30-day clinical response rate was significantly higher in the GnRH + CP group than in the GnRH group. Intervals to first estrus and to conception, proportion in heat by day 21 after treatment, and pregnancy rate by 90 days did not differ significantly between the groups. The same relationships held in a subset of cows with P₄≥1 ng/mL at treatment. Fewer cows in the GnRH + CP group became pregnant by day 90 after treatment, but this difference was not significant. These results suggest that simultaneous GnRH and cloprostenol treatment of all cows with cystic ovaries cannot be recommended at this time.     

The effect of intra-ruminal selenium pellets on growth rate, lactation and reproductive efficiency in dairy cattle

In each of two dairy herds (A and B), rising yearling heifers (Trial 1) and adult cows (Trial 2) were assigned to three treatment groups. Untreated animals were compared to animals treated with either two or four intra-ruminal pellets containing 3 g of elemental selenium. The administration of pellets at the recommended dose (two pellets per animal) was effective in elevating whole blood glutathione peroxidase activity and selenium concentration to over 10 times those of control animals. In Trial 1, a 15% response in liveweight gain (p<0.001) occurred in yearling heifers in the herd with the lowest pre-treatment selenium status. In Trial 2, cows receiving two pellets produced a greater milk volume (p=0.06) and more milk solids (p=0.02) than untreated controls; an increase in volume of 5.4% and 8%, and in milk solids of 6.5% and 6.4%, were noted in herds A and B respectively. There was a trend towards decreasing somatic cell counts in milk from the treated cows when compared to controls, the four-pellet group in Herd A and the two-pellet group in Herd B being significantly different from their respective control group. No between-group differences were noted in calving-first service or calving-conception intervals, nor in the proportion of animals pregnant to first or all services. The administration of selenium at twice the recommended dose rate yielded no additional response above that noted after the administration of the recommended dose. The results of this study support the use of currently recommended Ministry of Agriculture and Fisheries selenium reference ranges in cattle for the prediction of a response to supplementation.     

不同日粮对肉牛育肥效果研究

育肥牛试验选用 1 5～ 2 0周岁秦杂阉牛 2 0头 ,随机分为试验组和对照组 (P >0 0 5 ) ,试验期 60d。结果表明 ,试验组日增重 1 2 1kg/头 ,对照组 0 67kg/头 ,试验组比对照组多增加 0 5 4kg ,提高 80 % ,差异极显著 (P <0 0 1)。试验期试验组每头牛利润 185 4 4元 ,对照组每头牛利润 96 2 5元 ,试验组每头牛比对照组多收益 89 19元 ,每头牛日增利润 1 4 9元。     

The toxic effect of massive doses of calciferol on dairy cows

Extract

Evidence that feeding massive doses, of calciferol prior to calving may be a useful method of preventing milk fever was obtained by Hibbs and co-workers (1950, 1951) at Ohio State University. The treatment causes a rise in serum calcium and if dosing is suitably timed the post-partum fall in serum calcium may be countered, thus making up for the presumed parathyroid failure which occurs at this lime and which is believed by many to be the underlying cause of milk fever.     

The effects of varying the interval from follicular wave emergence to progestin withdrawal on follicular dynamics and the synchrony of estrus in beef cattle

The objective of this experiment was to examine the effects of varying the interval from follicular wave emergence to progestin (controlled internal drug-releasing insert, CIDR) withdrawal on follicular dynamics and the synchrony of estrus. A secondary objective was to assess the effects of causing the dominant follicle (DF) to develop in the presence or absence of a corpus luteum (CL) on follicular dynamics and the synchrony of estrus and ovulation. The experiment was designed as a 2 x 2 x 2 factorial arrangement of treatments with injection of GnRH or estradiol-17 beta and progesterone (E2 + P4) at treatment initiation, duration of CIDR treatment, and injection of PG (prostaglandin F2 alpha) or saline at the time of CIDR insertion as main effects. Estrous cycles (n = 49) in Angus cows were synchronized, and treatments commenced on d 6 to 8 of the estrous cycle. Cows were randomly assigned to receive a CIDR containing 1.9 g of P4 for 7 or 9 d. Approximately half the cows from each CIDR group received either GnRH (100 micrograms) or E2 + P4 (1 mg of E2 + 100 mg of P4) at CIDR insertion. Cows in GnRH or E2 + P4 groups were divided into those that received PG (37.5 mg) or saline at CIDR insertion. All cows received PG (25 mg) 1 d before CIDR removal. Daily ovarian events were monitored via ultrasound. The intervals from GnRH or E2 + P4 treatment to follicular wave emergence were 1.4 and 3.3 d, respectively (P < 0.05). The interval from follicular wave emergence to CIDR removal was longer (P < 0.05) for cows treated with GnRH (6.6 d) than those treated with E2 + P4 (4.7 d) and longer (P < 0.05) for those fitted with a CIDR for 9 d (6.5 d) than those with a CIDR in place for 7 d (4.8 d). Cows treated with PG or GnRH at CIDR insertion had a larger (P < 0.05) DF at CIDR removal than those treated with saline or E2 + P4. Treatment with a CIDR for 9 d also resulted in a larger (P < 0.07) DF at CIDR removal compared with cows fitted with a CIDR for 7 d. The interval from CIDR removal to estrus was shorter (P < 0.05) in cows treated with PG than those treated with saline. The synchrony of estrus and ovulation was not affected by any of the treatments (P > 0.05). Altering the interval from follicular wave emergence to progestin removal or creating different luteal environments in which the DF developed caused differences in the size of the DF at CIDR removal and the timing of the onset of estrus, but it did not affect the synchrony of estrus or ovulation.     

Administration of single short-acting doses of GnRH antagonist modifies pituitary and follicular function in sheep

Current study determined the effect of two different single subcutaneous doses (1.5 and 3 mg) of GnRH antagonist (GnRHa) on pituitary and follicular function in non-lactating cyclic ewes. Both doses abolished the pulsatile secretion of luteinizing hormone (LH) for at least 3 days and decreased mean LH concentration during 6 days (0.64 +/- 0.09 for control and 0.54 +/- 0.05, P < 0.005, and 0.46 +/- 0.02, P < 0.00001, for 1.5 and 3 mg, respectively). Supply of GnRHa decreased the number of large dominant follicles, so the total number of smaller follicles, 2-3 mm in size, increased in both treated groups from day 0, reaching its maximum at day 2 in ewes treated with 1.5 mg (19.83+/-1.05 versus 5.83 +/- 0.50 in the control, P < 0.005) and at day 4 in sheep treated with 3mg (18.67 +/- 0.65 versus 5.50 +/- 0.65 in the control, P < 0.0001). However, the analysis of follicular function in terms of inhibin A indicated a possible effect of the higher dose of GnRHa on follicular function. The pattern of inhibin secretion in the group treated with 3mg of GnRHa decreased after the first 48 h, reaching its lowest value on day 4.5 (182.59 +/- 3.75 to 140.28 +/- 9.91 pg/ml, P < 0.05) concentration significant lower than control sheep (171.93 +/- 6.21 pg/ml, P +/- 0.01) or treated with 1.5 mg (168.04 +/- 7.16 pg/ml, P+ /- 0.05). Hence, the use of 1.5 mg would be more suitable to induce the presence of a high number of follicles able to grow to preovulatory sizes.     

影响奶牛产犊间隔因素的分析

经对徐州市某奶牛场约800头荷斯坦奶牛1998到1999年产犊间隔与产犊季节、产奶量、产犊胎次、犊牛初生重、犊牛性别等基础资料进行分析，结果表明：产犊季节对产犊间隔有极显著的影响（P＜0.01）；奶牛的产奶量对产犊间隔也有极显著的影响（P＜0.01）；产犊胎次、犊牛初生重及犊牛性别对产犊间隔无显著影响（P＞0.05）。     

理囊散治疗卵泡囊肿不孕奶牛血清白介素与激素的相关性分析

探讨理囊散治疗卵泡囊肿不孕奶牛血液生殖激素和白介素含量关系,分析其相关性与回归方程.用ELISA法测定理囊散治疗卵泡囊肿不孕奶牛前后血清中促卵泡激素（FSH）、促黄体激素（LH）、孕激素（P）和雌二醇（E2）的浓度以及血清IL-1、IL-6含量,统计分析了4种激素和两种白介素间的相关关系与回归方程.结果表明,IL-1、IL-6与P呈正相关,与FSH、LH、E2为负相关.提示卵泡囊肿不孕奶牛血清中白介素与激素的分泌存在一定的相关性.     

药草复方制剂对奶山羊体增重和免疫指标的影响

为了研究不同药草复方对奶山羊生长性能及血清生化指标的影响,试验选用体况良好、体重相近(24.09±1.25)kg的4月龄崂山奶山羊公羊16只,随机分为4组,即对照组和3个试验组,每组4个重复。对照组饲喂基础日粮,3个试验组在日粮中分别添加1.2%的复方紫锥菊提取物(试验Ⅰ组)、四君子散(试验Ⅱ组)、强壮散(试验Ⅲ组)。结果:(1)就平均日增重和料重比两项综合来看,试验I组的效果更为明显;(2)各中药复方均可提高奶山羊血清中免疫球蛋白G的含量,且复方紫锥菊提取物还可提高血清中免疫球蛋白A的含量。结果表明,自制各药草复方不仅可提高羊只的体增重,而且还可提高其免疫力,效果以复方紫锥菊提取物制剂为最好。     

Experimental use of prostaglandin F2 alpha to synchronize estrus in cattle]

Experiments were conducted for the use of prostaglandin to synchronise oestrus in dairy cows. One single dose of 5 mg F2-Alpha prostaglandin was administered via the intrauterine route. The reference values of the control groups were matched by first insemination following induced oestrus among the best of the test animals which were inseminated twice. These values reached 72 and 96 hours following application accounted for 46.7 and 50.0 per cent. The yellow body phase, a prerequisite for oestrus production by prostaglandins, had been induced in the test animals by cycle blocking, using gestagen. Possible use of the method in a bio-engineering context for large-scale oestrus synchronisation in cows is discussed.     

The effect of claw trimming on the hoof health of Swedish dairy cattle

A 2-year experiment on the effect of claw trimming on hoof health was performed in 77 Swedish dairy herds (3444 dairy cattle) selected on herd size, breed composition and membership in the official milk-recording scheme. In the autumn, cows within each herd were blocked according to breed, parity and stage of lactation and allocated to two treatments: autumn trimming (AT) or no autumn trimming (NAT). Outcome variables were claw measurements and prevalence of hoof lesions and lameness (measured at spring trimming) and the need for hoof treatments between scheduled trimmings. At spring trimming, NAT cows had longer and shallower claws than AT cows. The average net growth of the toe wall was greater for AT than for NAT cattle, with a marked variation between housing systems. Most hoof lesions present at AT had disappeared at the subsequent spring trimming. Controlled for clustering by herd-within-year and for the effects of individual-and herd-level covariates, AT cattle at spring trimmings had significantly lower odds of lameness (OR=0.66) and of haemorrhages of the sole or white-line (OR=0.86), sole ulcer (OR=0.59) and white-line fissure or double sole (OR=0.71)-but not of moderate-to-severe heel-horn erosion or dermatitis (OR=0.96). Acute hoof treatments between claw trimmings were more common in the NAT group (OR=2.02).