首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
A high incidence (about 70%) of alteration in endometrial epidermal growth factor (EGF) profile, i.e., loss of 2 peaks on days 2–4 and 13–14, has been linked to a reduced fertility in multiparous repeat breeder Holstein cows. However, the EGF profile in Holstein heifers and other breeds (types) of cattle has not been investigated. In study 1, EGF concentrations were determined using endometrial tissues obtained by biopsy on days 3, 7 and 14 from 84 fertile Holstein heifers to obtain a normal range and 53 repeat breeder Holstein heifers to estimate incidence of alterations in the EGF profile. In repeat breeder heifers, EGF concentrations were similar to fertile controls on 3 days and five animals (9.4%) had an altered EGF profile with EGF concentrations below the normal range on days 3 and 14. In study 2, EGF concentrations on day 3 were repeatedly examined from the nulliparous period to the third postpartum period in 28 Holstein (dairy) and 47 Japanese Black (beef) cattle. The effect of parity on EGF concentrations on day 3 was different between Holstein and Japanese Black cattle. In Japanese Black cows, the EGF concentrations were consistently high throughout the study period, while in Holstein cows, the EGF concentrations decreased after the second calving. In conclusion, unlike multiparous repeat breeder Holstein cows, an altered EGF profile may not be a major cause of repeat breeding in Holstein heifers, and the peak EGF concentrations around day 3 may decrease even in fertile populations of multiparous dairy cows, but not in beef cows.  相似文献   

2.

Background

Measurement of salivary cortisol has been used extensively as a non-invasive alternative to blood sampling to assess adrenal activity in ruminants. However, there is evidence suggesting a considerable delay in the transfer of cortisol from plasma into saliva. Previous studies in cattle have used long sampling intervals making it difficult to characterise the relationship between plasma and salivary cortisol (PLCort and SACort, respectively) concentrations at different time points and determine whether or not such a time lag exist in large ruminants. Therefore, the objective of this study was to characterise the relationship between plasma and salivary cortisol and determine if there is a significant time lag between reaching peak cortisol concentrations in plasma and saliva across a 4.25 h time-period, using short sampling intervals of 10–15 min, following social separation in dairy cattle.Five cows were separated from their calves at 4 days after calving, and six calves were separated from a group of four peers at 8 weeks of age. Following separation, the animals were moved to an unfamiliar surrounding where they could not see their calves or pen mates. The animals were catheterised with indwelling jugular catheters 1 day before sampling. Blood and saliva samples were obtained simultaneously before and after separation.

Results

In response to the stressors, PLCort and SACort increased reaching peak concentrations 10 and 20 min after separation, respectively. This suggested a 10 min time lag between peak cortisol concentrations in plasma and saliva, which was further confirmed with a time-series analysis. Considering the 10 min time lag, SACort was strongly correlated with PLCort (P < 0.0001).

Conclusions

Salivary cortisol correlates well with plasma cortisol and is a good indicator of the time-dependent variations in cortisol concentrations in plasma following acute stress. However, there is a time lag to reach peak cortisol concentrations in saliva compared to those in plasma, which should be considered when saliva samples are used as the only measure of hypothalamic-pituitary-adrenal axis response to stress in cattle.  相似文献   

3.
本研究以8个牛品种为研究对象,利用与大理石花纹评分基因相关的7个微卫星位点结合DNA池分析技术,探讨微卫星DNA多态性与8个牛品种大理石花纹评分间的关系,并根据性状同质性原理预测品种组合,以加快生产出高端"雪花"牛肉。结果表明:日本和牛与荷斯坦牛、安格斯牛、渤海黑牛的相似性系数均超过0.8,而日本和牛与其他牛品种的的相似性系数均小于0.8。利用MEGA4软件采用邻接法进行聚类,利木赞牛与西门塔尔牛先聚合在一起,再与草原红牛聚合;渤海黑牛与鲁西黄牛2个地方良种聚合在一起,以上5个品种聚为第1大类。荷斯坦牛与日本和牛聚合,再与安格斯牛聚在一起,它们聚为第2大类。根据本研究结果和国外肉牛杂交生产实践,从牛肉大理石花纹性状的同质性出发,建议利用日本和牛、荷斯坦牛为亲本,杂交生产高档"雪花"牛肉,以解决我国的肉牛牛源短缺问题。  相似文献   

4.

Background

The effects of lameness on fertility have been documented frequently but few data are available from seasonally breeding, pasture-based herds (such as those used in Ireland) where cows are housed during the winter months but managed at pasture for the remainder of the year. This study determined the prevalence of lameness in a group of 786 cows in 10 pasture-based Irish dairy herds before, during and after the breeding season and assessed the relationship between lameness and the reproductive performance in these herds through serial locomotion scoring during the grazing period.

Results

Lameness prevalences of 11.6 % before, 14.6 % during and 11.6 % after the breeding season were found and these compared favourably to results from housed cattle and are similar to other studies carried out in grazing herds. A Cox proportional hazards model with locomotion score as time varying covariate was used. After controlling for the effect of farm, month of calving, body condition score at calving, body condition score loss after calving and economic breeding index, cows identified as lame during the study were less likely to become pregnant. Cows lame before the earliest serve date but no longer lame during the breeding season, cows becoming lame after the earliest serve date and cows identified lame both before and after this date were respectively 12 %, 35 % and 38 % less likely to become pregnant compared to cows never observed lame during the study. However, these findings were only significant for cows becoming lame after the earliest serve date and cows lame both before and after the start of breeding.

Conclusions

This study found that the reproductive efficiency was significantly (p < 0.05) lower in cows becoming lame during the breeding season and cows lame before and during the breeding season compared to non-lame cows. Cows no longer lame during the breeding season had a lower Submission Rate to first serve within 3 weeks of earliest serve date. However, the Pregnancy Rate was not significantly (p > 0.05) lower in these animals compared to cows never diagnosed as lame. In addition to lameness status, nutritional status and genetics were found to influence the reproductive performance in pasture-based Irish dairy herds.  相似文献   

5.
To compare the changes in the insulin reaction of Holstein dairy cows and Japanese Black cows (JB) during the periparturient period, the insulin resistance test in vivo and lymphocytes proliferation with insulin in vitro were performed. Ten healthy Holstein dairy cows (Holstein group) and 10 healthy JB cows (JB group) used in this study were observed on days 60, 40, and 20 before calving and days 7 and 20 after calving. In insulin resistance reaction in vivo and in vitro, a low insulin-stimulated glucose disposal rate and lymphocyte proliferation with insulin were observed in the Holstein group compared with the JB group during the experimental period. An analysis of the lymphocytes cultured with insulin showed that the percentage of CD4+CD45R- T cells in the Holstein group was significantly lower than that of the JB group before day 20. These findings indicate that T cells reaction to insulin in healthy periparturient Holstein cows is lower than that in Japanese Black.  相似文献   

6.
The objective of this study was to examine the effects of metritis and subclinical hypocalcemia on reduction of uterine size in dairy cows using ultrasonography and sonomicrometry. Four piezoelectric crystals were implanted via laparotomy into the myometrium of the pregnant uterine horn of 12 pluriparous Holstein Friesian cows 3 weeks before the calculated calving date. Sonometric measurements were conducted daily from 2 days before parturition (= Day 0) until Day 14 after calving and then every other day until Day 28. Distances between adjacent crystals were expressed in relation to reference values obtained before calving. The diameter of the formerly pregnant uterine horn was measured using transrectal B-Mode sonography starting on Day 10. Cows were retrospectively divided into the following groups: cows without metritis (M–; n = 7), cows with metritis (M+; n = 5), cows with normocalcemia (SH–; Ca > 2.0 mmol/l on Days 1 to 3; n = 5) and cows with subclinical hypocalcemia (SH+; Ca < 2.0 mmol/l in at least one sample between Days 1 and 3; n = 7). Metritis did not affect (P > 0.05) sonometric measurements, but the diameter of the formerly pregnant horn was larger (P ≤ 0.05) between Days 15 and 21 in M+ cows than in M‒ cows. Reduction in uterine length in hypocalcemic cows was delayed (P ≤ 0.05) between Days 8 and 21 compared with normocalcemic cows, but the uterine horn diameter was not related to calcium status. In conclusion, both diseases affected reduction of uterine size until Day 28. Cows with metritis had a larger uterine diameter, possibly attributable to accumulation of lochia, and cows with subclinical hypocalcemia had delayed reduction of uterine length, presumably related to reduction of myometrial contractility.  相似文献   

7.
Calving is an intrinsically risky process that can cause welfare and economic problems. The objective of this study was to assess the effect of the nonsteroidal anti-inflammatory drug meloxicam on various physiological and behavioral measures which can be related to pain in cattle. Sixty Friesian dairy cows from first to sixth parity were studied around calving and were randomly allocated into 2 homogeneous groups relative to parity and treated with either meloxicam or a placebo after calving. Treatments were administered on average 3.4 hours after calving, within a maximum of 6 hours. Calf positions at calving and calving assistance (unassisted or easy manual pull) were recorded. Milk production, rectal temperature, and activity (calculated as the number of steps per hour) were measured on each cow. From a subsample of 20 cows, haptoglobin (Hp) and serum amyloid A (SAA) concentrations were also obtained. The following behaviors were observed on video recordings: posture, changing posture, location of cow in pen, feeding, and tail up behaviors 2 days before and after calving. Statistical analysis was carried out with the SAS software using MIXED or GENMOD procedures. Most variables showed a parity and/or time effect around calving. This study did not demonstrate any significant effect of meloxicam on milk production or on acute phase responses of Hp and SAA. However, postcalving activity was significantly increased in meloxicam-treated heifers.  相似文献   

8.
The aim of the present study was to investigate the changing profiles of plasma metabolic hormones during the ovarian cycles of beef and dairy cattle. We used 16 non-pregnant, non-lactating Japanese Black beef cattle (6 heifers and 10 cows; parity=2.3 +/- 0.8) and 12 multiparous Holstein dairy cows (parity=3.0 +/- 0.3). Blood samples for hormonal analysis (growth hormone, GH; insulin-like growth factor-I, IGF-1; insulin; and progesterone, P4) were obtained twice weekly for 40 days before artificial insemination for Japanese Black cattle and from 50 to 100 days postpartum for Holstein cows. Luteal phases were considered normal if the P4 concentrations for at least 3 time points over the course of 7 days remained above 1 ng/ml and at least 2 of the time points were above 2 ng/ml. The patterns of the ovarian cycles were classified into two types (normal or abnormal, such as having prolonged luteal phase and cessation of cyclicity) on the basis of the plasma P4 profiles. The plasma concentrations of IGF-1 in both breeds increased transiently during the preovulatory period when the P4 levels were low and decreased to lower levels during the luteal phase when the P4 levels were high. The plasma concentrations of insulin in the 3(rd) week of normal ovarian cycles when the plasma P4 concentration dropped to less than 1 ng/ml were higher than those at other time points in the Japanese Black cattle, but not in the Holstein cows. The plasma concentrations of GH did not change during the ovarian cycle in either breed. In conclusion, the present study indicates that the plasma IGF-1 concentration increases during the follicular phase (low P4 levels) and decreases during the luteal phase (high P4 levels) in non-lactating Japanese Black and lactating Holstein cattle. The results suggest that ovarian steroids, rather than nutrient status, may be related to the cyclic changes in IGF-1 secretion from the liver in cattle.  相似文献   

9.
A 2-yr study was conducted at the Range Cattle Research and Education Center, University of Florida – Institute of Food and Agricultural Sciences (IFAS) (Ona, FL), to evaluate differences in the metabolism of Cu and Se of Angus (Bos taurus) and Brahman (Bos indicus) cattle. Thirty-two pregnant beef cows (n = 8 Brahman and 8 Angus/yr) were enrolled in the study in the first trimester of gestation. This study consisted of three phases: 1) restriction (day 0 to 90), 2) supplementation (day 91 to 150), and 3) calving. During all three phases, cows were individually fed and housed in partially covered drylot pens. During the restriction and supplementation phases, cows were provided a 1.5 kg/d of a grain-based concentrate supplement, which was fortified with flowers of S (50 g of supplemental S/cow daily; restriction phase) or Cu and Se (100 and 3 mg/d of Cu and Se, respectively; supplementation phase). Blood and liver samples were collected from all cows at 30 d intervals and from both cows and calves within 24 h of calving. Colostrum and milk samples were collected at calving and 7 d after birth. All data were analyzed using the MIXED procedure of SAS, where cow and calf were the experimental unit. During the restriction phase, a breed × day effect (P = 0.03) was observed where Brahman had greater liver Cu concentration than Angus cows in all sampling days. For liver Se concentration, a tendency (P = 0.07) for a breed effect was observed where Angus cows tended to have greater liver Se concentration than Brahman. During the supplementation phase, breed (P < 0.001) and day (P < 0.01) effects were observed, where Brahman cows had greater liver Cu concentration than Angus. For liver Se concentration, a day effect (P < 0.001) was observed, where liver Se concentration increased (P < 0.001) from day 90 to 120 and remained unchanged (P = 0.86) until day 150. At calving, no effects of breed (P = 0.34) were observed for liver Cu concentration of cows; however, Brahman calves tended (P = 0.09) to have greater liver Cu concentration than Angus calves. For Se liver concentration at calving, Angus cows tended (P = 0.07) to have greater liver Se concentration than Brahman cows; however, no breed differences (P = 0.70) were observed for liver Se concentration of calves at birth. In summary, substantial differences in multiple indicators of Cu and Se status were observed between Angus and Brahman cattle, implying that Angus and Brahman cattle possibly have different mechanisms to maintain adequate Cu and Se status.  相似文献   

10.
Data from 26 Japanese Black cows were collected to clarify the effects of supplemental β‐carotene on colostral immunoglobulin (Ig) and plasma β‐carotene and Ig in the cows. Cows were assigned to control or β‐carotene groups from 21 days before the expected calving date to 60 days after parturition. Supplemental β‐carotene was provided at 500 mg/day in the β‐carotene group. Supplemental β‐carotene drastically increased plasma β‐carotene concentrations in the cows from parturition to 60 days after parturition, and plasma β‐carotene concentrations in the control and β‐carotene groups at parturition were 202 and 452 μg/dl, respectively. Supplemental β‐carotene had no effects on plasma IgG1, IgA or IgM concentrations at parturition. Supplemental β‐carotene increased colostral IgG1 concentrations in the cows, but colostral β‐carotene, IgA and IgM concentrations were not affected by supplemental β‐carotene. These results indicate that supplemental β‐carotene is effective to enhance colostral IgG1 concentrations and plasma β‐carotene concentrations in Japanese Black cows.  相似文献   

11.
The aim of this study was to estimate genetic parameters for superovulatory response traits in order to explore the possibility of genetic improvement in Japanese Black cows. We analyzed 19 155 records of the total number of embryos and oocytes (TNE) and the number of good embryos (NGE) collected from 1532 donor cows between 2008 and 2018. A two-trait repeatability animal model analysis was performed for both. Because records of TNE and NGE did not follow a normal distribution, the records were analyzed following no, logarithmic, or Anscombe transformation. Without transformation, the heritability estimates were 0.26 for TNE and 0.17 for NGE. With logarithmic transformation, they were 0.22 for TNE and 0.18 for NGE. With Anscombe transformation, they were 0.26 for TNE and 0.18 for NGE. All analyses gave similar genetic correlations between TNE and NGE, ranging from 0.60 to 0.71. Spearman’s rank correlation coefficient between breeding values of cows with more than 10 records was ≥0.95 with both transformations. Thus, the genetic improvement of TNE and NGE of donor cows could be possible in Japanese Black cattle.  相似文献   

12.
The paper describes the postpartum (pp) reproductive performance of 252 dairy cows in 2 areas in Iceland, in the north (Eyjafjörður) and in the south (Skeið), during a 12 months period.First pp ovulation occurred significantly earlier in primiparous cows, in cows in Skeið and in cows that calved in September—November.The average time of first pp artificial insemination (ai) was 72 days in both areas. Conception rate to first ai in these cows was 58 % in Eyjafjörður and 53 % in Skeið and the number of ai per conception was 1.6 and 1.8, respectively. In Eyjafjörður, 23 % of the cows were inseminated at the time of first pp ovulation. Sixtytwo percent of these cows conceived. In Skeið, 20 cows were inseminated at the time of first pp ovulation, and 9 or 45 % of these cows conceived. The interval from calving to conception was, on the average, 92 days in Eyjafjörður and 100 days in Skeið.Comparison of results from individual farms showed increase in number of conceptions to first pp ai (35–72 %) and decrease in number of services per conception (2.0–1.3) with increased mean number of days from calving to first ai (62–82 days).  相似文献   

13.
A total of 2434 calving records from seven calving seasons were analyzed by the least-squares and chi-square procedures to study the influences of breeding group, age of dam, sex and birth weight of calf and dam weight at calving on the time of day of parturition. Frequency of day calving (0630 ± 030 to 1900 h) was slightly but not significantly higher than night calving (1900 h to 630 ± 030). The frequency of night calving was higher among heifers compared with the older cows. The cows which calved after May 15 (the last one third period of pregnancy) had higher frequency of day calving compared with those that calved earlier. The frequency of daytime calving was higher among the cows that weighed at most one standard deviation below the average compared to heavier cows of comparable age.  相似文献   

14.
Maintaining genetic diversity and inbreeding control are important in Japanese Black cattle production, especially in remote areas such as the islands of Okinawa Prefecture. Using a single-nucleotide polymorphism (SNP) array, we evaluated the genetic diversity and genomic inbreeding in Japanese Black cows from the islands of Okinawa Prefecture and compared them to those from other locations across Japan. Linkage disequilibrium decay was slower in cows in the islands of Okinawa Prefecture. The estimated effective population size declined over time in both populations. The genomic inbreeding coefficient (FROH) was estimated using long stretches of consecutive homozygous SNPs (runs of homozygosity; ROH). FROH was higher in the cows on the islands of Okinawa Prefecture than on other locations. In total, 818 ROH fragments, including those containing NCAPG and PLAG1, which are major quantitative trait loci for carcass weight in Japanese Black cattle, were present at significantly higher frequencies in cows in the islands of Okinawa Prefecture. This suggests that the ROH fragments are under strong selection and that cows in the islands of Okinawa Prefecture have low genetic diversity and high genomic inbreeding relative to those at other locations. SNP arrays are useful tools for evaluating genetic diversity and genomic inbreeding in cattle.  相似文献   

15.
Associations between rearing conditions and the risk of culling in dairy cows were studied by survival analysis. Data were collected from 1039 Swedish Red cows, 1029 Swedish Holsteins, and 56 cows of other milk or cross-breeds, representing all female animals born in 109 Swedish herds during 1998. Length of productive life was defined as the number of days from 1st calving to culling. The applied Weibull proportional hazards model included time-independent effects of breed, housing from 3 to 7 months of age, number of housing changes before calving, grazing before 1st calving, herd median age at 1st calving, age at 1st calving, cow housing, herd lactational incidence risk of veterinary-reported clinical mastitis, and the random effect of herd. Time-dependent effects were year, month, the interaction year by month, parity, number of breedings, pregnancy status, the interaction parity by pregnancy status, herd mean milk-production level, relative milk yield within breed-parity, and veterinary-reported clinical mastitis. The lactation was divided into six stages in which pregnancy status was assumed to be known by the farmer and culling could occur. Median productive life time in culled cows was 780 d and 14% of the records were censored due to terminated data collection. An individual calving age of 28.2–30.9 months was associated with the highest culling risk, 1.2-fold higher than calving at ≤25.3 months, whereas the risk decreased almost linearly with a higher herd median age at 1st calving. Housing in slatted pens with >7 calves from 3 to 7 months was associated with a 1.7-fold increase in risk, relative to litter pens. If a cow had changed housing system 4 times before 1st calving it increased the risk of culling 1.4 times, relative to two housing changes. These results show that rearing factors affect the productive life time of dairy cows in Swedish family operations.  相似文献   

16.
Eleven primiparous Holstein Friesian and their crossbred calves (F1, Japanese Black cattle × Holstein Friesian) and 10 multiparous Holstein Friesian and their Holstein Friesian calves were used to evaluate vitamin E status in periparturient period. Plasma α‐tocopherol (α‐toc) concentrations of the multiparous cows were significantly higher than those of the primiparous cows from 60 days before expected calving to 90 days of lactation (P < 0.05). The multiparous cows had a further decrease in the concentrations of α‐toc and total lipid in plasma to the calving than the primiparous cows. Colostrum α‐toc concentrations in multiparous cows were significantly higher than those of the primiparous cows (P < 0.05). Plasma α‐toc concentrations of calves borne by the multiparous cows were significantly higher than those of the primiparous cows at 5 days of age (P < 0.05). Plasma α‐toc concentrations of calves were highest at 5 and 15 days of age in the calves borne by the multiparous and primiparous cows, respectively, and decreased thereafter till 90 days of age. The higher vitamin E status of multiparous cows over primiparous cows might have reflected nutritional composition in the rations. Their calves afforded higher plasma α‐toc levels after birth because of more α‐toc transfer via placenta and more α‐toc secretion in the colostrums thereafter. Plasma α‐toc concentrations of the calves might have decreased as the calves became dependent upon the solid feed of low vitamin E content.  相似文献   

17.
We investigated changes in the predicted functions of the rumen bacterial community in Japanese Black beef cattle during fattening. Nine cattle were fed a high-concentrate diet during the early, middle, and late fattening stages consecutively (10–14, 15–22, and 23–30 months of age, respectively). The rumen fluid and solid samples collected at each stage were subjected to sequencing analyses. The sequencing results were clustered and classified into operational taxonomic units (OTUs). Representative sequences and a raw counting table for each OTU were submitted to the Piphillin website. The predicted functions were revealed by the Kyoto Encyclopedia of Genes and Genomes database as the ratio of the total sequence. In the early stage, “Biosynthesis of secondary metabolites” was significantly higher in the fluid fraction than in the solid fraction. “Two-component system” in the middle stage was significantly lower and “Purine metabolism” in the late stage was significantly higher in the fluid fraction than those in the solid fraction. The fluid fraction was significantly correlated with acetic acid, propionic acid, and bacterial metabolism, such as “Biosynthesis of secondary metabolites” and “Sugar metabolism.” Moreover, the solid fraction was correlated with “Purine metabolism” and “Biosynthesis of secondary metabolism”. These results suggest that the rumen bacterial community in Japanese Black beef cattle adapts to changes in rumen conditions by altering their functions in response to a long-term high-grain diet.  相似文献   

18.
This retrospective study was conducted to confirm the relationship between pre- and postpartum metabolic parameters and postpartum reproductive performance and to clarify seasonal characteristics of the metabolic parameters by using our metabolic profile test (MPT) database of Japanese Black breeding herds. In evaluation 1, MPT databases of blood samples from multiparous cows collected prepartum and postpartum were divided into two groups according to calving interval, and each MPT parameter was compared. In evaluation 2, the same MPT databases used in evaluation 1 were divided into two groups according to the sampling period. Significant differences were found in the prepartal total protein and postpartal γ-glutamyltransferase in evaluation 1. In evaluation 2, significant differences were found in the prepartal and postpartal total protein, albumin/globulin ratio, and glucose. Clear seasonal differences in MPT results emphasized the usefulness of the MPT in breeding cattle herds fed home-pasture roughage and suggest that unsatisfactory reproductive performance during hot periods reflects inadequate nutritional content of the diet and possible reduced feed intake due to heat stress.  相似文献   

19.
Environmental factors such as the temperature–humidity index (THI) are known to affect reproductive parameters in cattle. Therefore, here, we examined whether there was any correlation between the THI and the reproductive performance of Japanese Black cattle by analysing the first‐service conception rates of 178,492 artificially inseminated cows across 9,833 herds in south‐western Japan over a 3‐year period. The daily mean (±SD) THI over the study period was 63.6 ± 11.3 (range: 41.4–81.5). The calving to first artificial insemination (AI) interval was significantly negatively correlated with THI in the month of AI (r = ?.75, p < .001), whereas conception rate to first AI (CRFA) showed a cyclical change that did not correspond with that of THI, resulting in a time lag between CRFA and THI in the month of AI. Furthermore, there was a stronger correlation between CRFA and THI between 3 and 2 months before AI (r = .76 vs. .83, p < .001) than in the month of AI (r = .34, p = .04). Therefore, this extensive field study showed that a decrease in THI was associated with declined reproductive performance in Japanese Black cattle and that the impact of the cold environment on the conception rate is attributable to a carryover effect from the cold season before AI rather than conditions at the time of AI.  相似文献   

20.

Background

This study was carried out to determine if an association exists between the shape of the lactation curve before it is influenced by the event of conception and the time from calving to conception in Norwegian dairy cattle. Lactation curves of Norwegian Red cows during 5 to 42 days in milk (DIM) were compared between cows conceiving between 43 and 93 DIM and cows conceiving after 93 DIM.

Methods

Data from 23,049 cows, represented by one lactation each, with 219,538 monthly test days were extracted from the Norwegian Dairy Herd Recording System, which represents 97% of all Norwegian dairy cows. Besides veterinary treatments, these records also included information on daily milk yield at monthly test days. The data were stratified by parity groups (1, 2, and 3 and higher) and time to conception periods (43-93 DIM and >93 DIM). The sample was selected using the following selection criteria: conception later than 42 DIM, calving season July to September, no records of veterinary treatment and the level of energy fed as concentrates between 8.69 and 12.83 MJ. The shape of the lactation curves were parameterized using a modified Wilmink-model in a mixed model analysis. Differences in the parameters of the lactation curves with different conception times were evaluated using confidence intervals.

Results

Lactation curves characterized by a low intercept and a steep ascending slope and a steep descending slope were associated with early conception across all parities. The peak milk yield was not associated with time of conception.

Conclusions

A practical application of the study results is the use of the shape of the lactation curve in future herd management. Groups of cows with impaired reproductive performance may be identified due to an unfavorable shape of the lactation curve. Monitoring lactation curves and adjusting the feeding strategy to adjust yield therefore may be useful for the improvement of reproductive performance at herd level.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号