营养因素对奶牛繁殖性能的影响及提高繁殖率的措施

近年来，一方面，牛群规模进一步扩大，饲养方法更科学，产奶量不断提高；另一方面，在追求高产的同时，奶牛繁殖性能有所下降。在生产中，奶牛繁殖性能的好坏与生产水平的高低有直接关系。影响奶牛繁殖性能的因素是多方面的，包括年龄、遗传、营养、疾病、人工授精技术、环境和管理等，适当的营养调控是提高奶牛繁殖性能的基础，是奶牛高产的关键，对于保障奶牛业稳定持续发展，进一步增加养殖效益等都有着积极的意义。     

影响奶牛繁殖性能的营养因素

随着奶牛业的快速发展,奶牛产奶量逐步提高,奶牛繁殖障碍性疾病发生有所上升,给奶牛产业造成了巨大的经济损失。营养是影响奶牛繁殖性能的重要因素之一,营养不良或营养过盛,都会对奶牛的发情、配种、受胎率、生殖系统功能及犊牛成活方面等产生不同程度的影响。本文对影响奶牛繁殖性能的营养因素进行综述,为合理饲养奶牛提供参考。     

营养对奶牛繁殖性能的影响

<正>饲料营养的全面合理是奶牛高繁殖率的基础,繁殖率高是保证奶牛终生产奶量和经济效益的关键。现将营养对奶牛繁殖性能的影响进行简单的介绍,供各奶牛场、奶牛养殖户参考。     

营养对奶牛繁殖性能的影响

影响奶牛繁殖性能的因素很多，但合理的饲料投人与平衡的营养水平是提高奶牛繁殖性能的基础，是奶牛高产高效的关键，现就几种主要营养成份对奶牛繁殖性能的影响简介如下。     

奶牛繁殖障碍的原因及提高奶牛繁殖率的措施

随着畜牧业生产结构的调整、人民生活水平的提高以及人们膳食结构的改变,使奶牛业得到进一步的发展,而提高奶牛繁殖率显得越来越重要。提高奶牛繁殖率,缩短产犊间隔,对于提高奶牛产奶量和奶牛生产、经济效益具有重要意义。笔者对引起奶牛繁殖障碍的病因及提高奶牛繁殖率的方法做以下分析,希望对养殖户有所帮助。     

影响奶牛繁殖性能的营养因素

影响奶牛繁殖性能的因素很多，本文就其能量、蛋白质、矿物质及维生素等各种营养因素做出总结。     

提高奶牛繁殖率技术措施

对于一个牛场来讲，繁殖技术管理的好坏将直接影响着整个牛群的生产水平，而繁殖水平的高低决不是做好某一项工作而奏效。只有不断改善繁殖管理，提高繁殖水平，以及与繁殖有关的各个环节必须采取综合技术措施，才能取得预期的生产效果。     

提高奶牛繁殖性能的几项措施

随着奶牛业的发展,奶牛养殖也趋向于科学化、精细化、效益化。但是,由于地区差异和生产力水平不同,奶牛生产性能表现的也不一样。繁殖管理是奶牛生产中的最为关键的环节之一。     

影响奶牛繁殖性能的因素与措施

奶牛的生产水平和养殖效益与奶牛繁殖性能密切相关。影响奶牛繁殖率性能的因素较多,归纳起来主要有：遗传因素、环境因素、营养水平、疾病、繁殖技术和饲养管理等诸多因素的影响。了解影响奶牛繁殖性能的因素,采取积极的应对措施来提高奶牛的繁殖率,对提高奶牛养殖户的经济效益具有重要意义。笔者结合多年的工作经验,简单介绍影响奶牛繁殖性能的因素和应对措施,以供参考。     

提高奶牛繁殖率的技术措施

随着奶牛业的发展，提高奶牛的繁殖率显得越来越重要。提高奶牛繁殖率，缩短产犊间隔，对于提高奶牛产奶量和奶牛生产经济效益具有重要意义。通过改善饲养管理条件、合理应用现代繁殖技术来提高繁殖率，可达到提高产奶量的目的。笔者结合实际，介绍如何提高奶牛繁殖率技术措施，供同行和养殖户参考。     

Risk factors for postpartum endometritis and the effect of endometritis on reproductive performance in dairy cows in Korea

The objectives of this study were to determine the risk factors for postpartum endometritis by evaluating several reproductive factors in individual cows, and to determine the effect of endometritis on the subsequent reproductive performance in dairy herds in Korea. The data, including health status, parity and body condition score (BCS) of cows, and calving date, were collected from 320 cows in eight dairy herds calving from January 2001 to October 2002. We used logistic regression to evaluate the effects of these factors on endometritis. A stepwise procedure, used to obtain the appropriate model with alpha=0.05, revealed that retained placenta, metabolic disorders and parity are the important risk factors for endometritis. The mean intervals from calving to first service and conception were prolonged (P<0.01) by 23 and 36 days, respectively, in the endometritis group compared to the non-endometritis group. The first service conception rate was lower (P<0.05) in the endometritis group (47.6%) than in the non-endometritis group (62.6%). The number of services per conception was higher (P<0.05) in the endometritis group (1.9) than in the non-endometritis group (1.6). We conclude that retained placenta, metabolic disorders and cow parity are strongly correlated with the development of postpartum endometritis, which decreases reproductive performance in dairy herds in Korea.     

Effect of feeding on reproductive performance in Finnish dairy cows

The effect of 2 types of feeding on the involution of the genital tract and on the fertility was studied in 79 Finnish dairy cows on a research farm. The cows were fed twice a day with home-produced feed in accordance with the Finnish feeding standard. The cows were divided according to the type of feed into a hay-urea group and a silage group. The cows were examined clinically by rectal palpation 3 times a week during 8 weeks postpartum. The time required for the complete involution of uterus and cervix was recorded. The cows in the silage group had a significantly longer time in uterine involution, a lower fertility rate at first insemination and a longer interval from calving to conception than those in the hay-urea group. The pregnancy rate in the first insemination was in the hay-urea group 91% and in the silage group 57%. The interval between calving and the first insemination was shorter in the hay-urea group than in the silage group: 71.4 +/- 10.6 and 74.0 +/- 10.3 days, respectively. The interval between calving and conception was in the hay-urea group significantly (p less than 0.01) shorter than in the silage group; 74.8 +/- 15.1 and 89.5 +/- 24.4 days, respectively.     

Effects of prostaglandin on the reproductive performance of dairy cows

A single injection of a synthetic analogue of prostaglandin F2 alpha (fenprostalene; Syntex) on the day of calving or between days 14 and 21 after calving did not affect the calving to first service interval, the number of services per conception or the conception rate of dairy cows. In a second trial, cows calved more than 45 days were injected once weekly with prostaglandin F2 alpha (dinoprost; Upjohn) or fenprostalene until served at the first detected oestrus. The calving to first service interval and the conception rate were not affected. Following injection of either prostaglandin, the spread in the pattern of onset of oestrus and the range in the proportion of cows (75 to 98 per cent) seen in oestrus within seven days were similar. This variation in the time of onset of oestrus after the administration of prostaglandin precludes limiting oestrus detection to four or five days per week, and is a major limitation to the use of prostaglandins in breeding programmes in dairy cows.     

Risk factors and the economic impact of ovarian cysts on reproductive performance of dairy cows in Korea

The objectives of this study were to determine the risk factors for development of postpartum ovarian cysts by evaluating several reproductive factors in individual cows, and to determine the economic impact of ovarian cysts on subsequent reproductive performance in dairy herds in Korea. The data, including cow parity, abnormal puerperium, endometritis, body condition score (BCS), and breeding status were collected from 634 cows in 9 dairy herds. We used logistic regression to evaluate the effects of these factors on ovarian cysts. A stepwise procedure, used to obtain the appropriate model with alpha=0.05, revealed that cow parity was the most important risk factor for ovarian cyst development within 8 weeks postpartum, while development of endometritis and BCS loss>or=1 from the dry period to 8 weeks postpartum were the most important risk factors for ovarian cyst development beyond 8 weeks postpartum. The occurrence of ovarian cysts beyond 8 weeks postpartum prolonged (P<0.01) the mean intervals from calving to first service (27 days) and conception (77 days), and increased (P<0.05) the culling rate (7.8%), while ovarian cyst development within 8 weeks postpartum did not affect (P>0.05) the mean intervals from calving to first service and conception or the culling rate. The economic loss resulting from the occurrence of ovarian cysts was estimated at approximately 823,996 won ($687) due to effects on the cost of nutrition, average growth of calves, labor and medical costs, and culling. These results suggest that cow parity is correlated with the development of ovarian cysts within 8 weeks postpartum, and endometritis and BCS loss>or=1 from the dry period to 8 weeks postpartum are correlated with the development of ovarian cysts after 8 weeks postpartum, which decreases reproductive performance and results in economic loss in dairy herds in Korea.     

The effect of protein-feeding strategy during lactation on performance of primiparous dairy cows fed total mixed ration

Fifty primiparous Finnish Ayrshire cows were used in 2×2 factorial study. The factors were the protein-feeding strategy: constant (cCP) or variable (vCP) protein content in concentrate during lactation and the use of a commercial health product from 2 weeks pre- to 8 weeks postpartum. On treatment cCP, the CP content of the concentrate was 180 g/kg in dry matter (DM) throughout the lactation, and on vCP treatment, the CP content was 210, 180 and 150 g/kg DM during lactation days 0-100, 101-200 and 201-305, respectively. The concentrate blends included barley, oats, rapeseed meal, molassed sugar beet pulp and minerals and vitamins. Grass silage and ensiled wet sugar beet pulp (100 g/kg DM in TMR) were used as forage. The forage-to-concentrate ratio in TMR was 55:45 on both treatments. The experimental period was 305 days of the first lactation.The average daily milk yield (cCP: 26.3 kg/day vs. vCP: 27.5 kg/day) was higher (P<0.05) when feeding concentrate with decreasing protein content, but the effect was not seen in an energy-corrected milk (cCP: 28.1 kg/day vs. vCP: 29.0 kg/day). Milk composition was not affected by the protein-feeding strategy. Protein-feeding strategy had no effect on DM intake (cCP: 18.5 kg/day vs. vCP: 18.9 kg/day). The efficiency of CP utilization (milk protein/CP intake) was higher (0.327 vs. 0.301; P<0.05) on vCP treatment during the last 100 days of lactation, but during the first 200 days of lactation, no significant difference was found. The average efficiency of CP utilization throughout the lactation was 0.32 with no difference between treatments. The protein-feeding strategy had no effect on the development of body condition scores of the cows. In mid-lactation, the cows on cCP treatment gained more weight than the cows on vCP treatment. The health product had no significant effect on production or feed intake. The results suggest that only small benefits can be obtained from feeding TMR to primiparous cows differing in CP content at various stages of lactation.     

The reproductive performance of New Zealand dairy cows after induction of calving

Induction of premature calving contributes to subsequent failure of some dairy cows to become pregnant and calve. Of a sample of 276 cows 16.7% failed to calve the following year despite the occurrence of oestrus relatively early after calving, and several matings. The cows which did conceive had a normal first-mating calving rate of 53.9%, requiring 1.7 matings per pregnancy. Two of the 18 survey herds under consideration suffered lengthy calving-to-first-mating oestrus intervals, presumably because the induced cows were in poor condition at the time of calving.     

复合酵母培养物对奶牛生产性能的影响

<正>近年来,国内外有很多关于酵母培养物在奶牛生产中应用的研究,在日粮中添加酵母培养物可以稳定瘤胃内环境,促进有益菌群的增殖(张连忠,2009),同时     

Risk factors for and reproductive outcomes of phantom cows on New Zealand dairy farms

AIMS: To determine some of the risk factors for cows not observed in oestrus within 35–42 days of an unsuccessful artificial insemination (AI; phantom cows), and the reproductive outcomes and effect of treatment of phantom cows.

MATERIALS AND METHODS: Over 2 years, in dairy herds from the Waikato (n=10) and Canterbury (n=4) regions of New Zealand, pregnancy diagnosis was carried out 35–42 days after AI on cows that had been inseminated in the first 3 weeks after the start of mating (PSM) but had not been seen returning to oestrus. Risk factors for phantom cows were analysed using a generalised linear mixed effect model.

In Year 1, all phantom cows were left untreated. In Year 2, phantom cows were categorised as having a corpus luteum (CL) (CL+ n=120), or having ovarian follicles ≥10 (n=101) or <10 (n=40)?mm in diameter. Cows with a CL were treated with cloprostenol or untreated and placed with bulls. Cows with no CL received intravaginal progesterone (P4) for 7 days, with injection of gonadotrophin-releasing hormone (GnRH) on Days 0 and 9, and cloprostenol on Day 7 followed by AI. Pregnancy diagnosis of all cows took place 100–120 days after PSM and interval to conception and final pregnancy rate determined.

RESULTS: Overall, of cows inseminated in the first 3 weeks after PSM that did not return to oestrus, 610/6,734 (9.1%) were phantom cows. From the final multivariable analysis, treatment for anoestrus, BCS ≤4.0 at mating, being 2 or >6 years of age, and pure-bred, and decreasing interval between calving and mating, until 98 days post calving, were associated with increased odds of being a phantom cow. Compared to all other groups of cows, phantom cows had a longer interval to conception (p<0.001) and a lower final pregnancy rate (p<0.001).

Treatment of CL+ cows or cows with follicles ≥10?mm did not affect reproductive outcomes (p>0.3). For cows with follicles <10?mm treatment decreased the final percentage not pregnant (3/27; 11%; p=0.01) and interval to conception (21 days; p=0.02) compared with controls (7/13; 54% and 37 days, respectively).

CONCLUSIONS AND CLINICAL RELEVANCE: Risk factors for phantom cows were identified that could be manipulated to reduce the number of phantom cows in a herd, in particular increasing BCS. Treatment of the majority of phantom cows did not improve reproductive performance.     

高产奶牛繁殖性能低的原因分析

在过去的几十年里,随着奶牛产奶量增加,奶牛的繁殖能力出现下降现象。人们从包括遗传学、生理学、营养学和管理学等方面去努力解释这一现象,并从动物、器官和细胞的角度进行研究。本文综述了影响奶牛繁殖性能的原因和后果。     

Effect of extruded linseed on productive and reproductive performance of lactating dairy cows

A total of 356 early lactation multiparous Holstein cows were used in a randomized complete block design to determine the effects of feeding extruded linseed on milk production and composition, and reproductive performance. Forty of these cows were randomly selected to study the effects of extruded linseed on milk fatty acid (FA) profile, individual feed intake and prostaglandin secretion. Cows were fed a 40:60 forage to concentrate ratio diet (17.9% CP, 27.7% NDF and 6.0% EE) ad libitum that was similar in composition between treatments except for the protein supplements that differed and were control (CTR: 4.9% extruded soybean) and linseed (LIN: 5.5% extruded linseed). Individual DM intake measured at 40 (23.0 kg/d) and 90 (24.2 kg/d) days in milk, and milk yield (45.0 kg/d) were not affected by treatment, but the lower (P < 0.05) milk fat percentage in cows fed LIN (2.65%) compared with CTR (2.86%) resulted in lower (P < 0.05) 4.0% fat-corrected milk yield for cows fed LIN (35.4 kg/d) compared with CTR (37.7 kg/d). Milk protein content was higher (P < 0.05) in LIN (3.04%) than in CTR (3.00%). The concentration of saturated FA was lower (P < 0.05) in milk fat from LIN (56.2%) compared with CTR (60.2%). Monounsaturated FA (35.7 vs. 32.7%) and polyunsaturated FA (8.0 vs. 6.9%) were higher in LIN (P < 0.05) than in CTR. Supplementation with LIN also increased (P < 0.05) the proportion of vaccenic acid (2.21 vs. 1.55%), total conjugated linoleic acid (0.91 vs. 0.72%) and n-3 FA (1.21 vs. 0.54%) in milk compared with CTR. Plasma concentrations of prostaglandin metabolite were numerically lower in LIN (106 pg/ml) compared with CTR (120 pg/ml) (P = 0.16) but reproductive performance was similar between treatments. In summary, extruded linseed reduced milk fat percentage and 4.0% fat-corrected milk yield and increased milk protein percentage and the content of healthy FA in milk without modifying DM intake, milk yield and reproductive performance.