Reproductive performance in the subsequent lactation of dairy cows previously treated for failure to be detected in oestrus

AIM: To describe the effect of treatment of cows not detected in oestrus (NDO) with progesterone (P4) and oestradiol benzoate (ODB) in one lactation, on the reproductive and productive performance in the subsequent lactation. METHODS: Cows (n=770 from nine herds) which were NDO 10 days before the planned start of the seasonal breeding programme (PSM) were blocked by herd, age (2 or >2 years old) and ovarian status (i.e. with or without a palpable corpus luteum; CL), and treated either with an intravaginal progesterone-releasing device and ODB and resynchrony, or were left as untreated controls. In the following lactation, data were collected on the occurrence of endometritis, NDO, breeding dates, pregnancy test results and milk production. The effect of treatment and ovarian status in the previous lactation on the incidence of disease, and the proportions submitted for service, conceived and pregnant in the subsequent lactation were analysed. Calving dates and intervals from start of breeding to first insemination and conception were analysed using Kaplan Meier survival analysis. Additional multivariate analyses were undertaken to include known confounders such as age, breed, herd, calving date and milk production, as well as the cyclic status (i.e. previously cycling, NDO, or "late-calving") in the previous lactation, to examine the potential "carryover" effects of previous status on the reproductive performance in the subsequent lactation. RESULTS: Treatment of NDO cows resulted in an earlier calving date (Julian calving date 214, 95% CI=207-221, vs 224, 95% CI=220-228; p=0.005), more female calves reared (31.4% vs 23.3%; p=0.01), and reduced risk of being NDO (33.9% vs 46.1%; p=0.002) in the subsequent lactation compared with controls. There were no differences in the incidence of peripartum disease, or the proportion of cows submitted, conceived or pregnant between the Treatment and Control groups in the subsequent lactation (p>0.2). Previously CL-positive (+ve) NDO cows were less likely to produce a female calf that was reared (19.0% vs 29.9%; p=0.005), more likely to be treated as NDO (26.4% vs 18.6%; p=0.02), less likely to conceive by the end of the subsequent lactation's breeding programme (82.2% vs 87.8%; p=0.09), and took longer to conceive (41 vs 33 days from the PSM to conception) than cows that were NDO-CL-negative (-ve) in the previous lactation. There was no interaction between ovarian status and treatment for any of the outcome variables (p>0.05). Cows that were NDO or late-calving in the previous lactation were more likely to be NDO (p<0.005), treated as NDO (p<0.005), and have longer PSM to conception intervals (p<0.005) in the subsequent lactation than cycling herdmates, despite inclusion of factors known to confound reproductive performance in analyses. CONCLUSIONS: Treatment of NDO cows resulted in more female calves reared, earlier calving and a reduced risk of being NDO in the subsequent lactation. Status (i.e. NDO-CL+ve or NDO-CL-ve) affected some reproductive measures in the subsequent lactation, and the effect of treatment in the subsequent lactation differed between the two groups for some measures. Reproductive performance in the subsequent lactation was not improved despite the earlier calving date and longer calving to PSM intervals. Additionally, the previous season's status was still important in the subsequent season's reproductive performance, despite adjusting for known confounders of fertility. CLINICAL RELEVANCE: The economic benefits from treatment of NDO cows are likely limited to effects of an earlier calving date and potential for longer lactation and increased milk yield, increased number of calves derived from artificial insemination and from a reduced number of NDO cows in the subsequent lactation. Effects of improved reproductive performance in the subsequent lactation were not demonstrated and hence should not be included in any economic analysis of therapy of NDO cows.     

Comparison of four methods for detection of oestrus in dairy cows with resynchronised oestrous cycles

OBJECTIVE: To compare the sensitivity and positive predictive value of four methods for detection of oestrus in dairy cows with resynchronised oestrous cycles. PROCEDURE: Oestrous cycles in cows in three herds were synchronised for a first round of artificial insemination (AI) and then resynchronised for a second round of AI. Sensitivity and positive predictive value of four aids (pedometers, radiotelemetric transmitters [HeatWatch; HW], tail-paint and heatmount detectors) that were used to detect the resynchronised oestrus were compared. Milk progesterone concentration and pregnancy testing at 12 weeks were used as the reference standard for cows being in oestrus. RESULTS: The mean sensitivity and positive predictive value for detecting the resynchronised oestrus, for each aid that was used, was > 80%. Tail-paint was significantly more sensitive at detecting oestrus compared to heatmount detectors (P = 0.002), but not significantly more sensitive than pedometers (P = 0.07) or HW (P = 0.55) for detecting oestrus (91.3, 85.7; 81.4 and 88.4%, respectively). Positive predictive value of HW for detecting oestrus was greater than tail-paint (P = 0.014) and heatmount detectors (P = 0.024) but not pedometers (P = 0.25; 100, 91.7, 92.9 and 87.5%, respectively). Positive predictive value of heatmount detectors was greater than pedometers in herd C (93.4% vs 73.3%; P = 0.035) but not in herds A (95.0% vs 90.0%; P = 0.56) or B (90.8% vs 100%; P = 0.10). No other significant differences in sensitivity or positive predictive value of detection of oestrus were found between aids. CONCLUSION: Tail-paint, heatmount detectors, pedometers and HW provide a high sensitivity (> 80%) and positive predictive value (> 85%) of detecting oestrus in dairy cows with resynchronized oestrous cycles.     

The effect of oestrus on milk production in cows

The rectal temperatures, pulse rates and milk yields of 44 Ayrshire and 38 Friesian cows were recorded during oestrus and compared with values obtained after oestrus had ceased. The fat, solids-non-fat (SNF) and protein percentages and the cell counts of milk samples were also compared. Forty of the cows were housed in cubicles and 42 were kept loose in yards. During oestrus rectal temperatures and pulse rates were significantly raised and milk yields were lowered. Milk had, on average, significantly higher fat contents and cell counts and lower SNF and protein contents than post-oestrous milk. The differences due to oestrus between the cows kept in cubicles and yards were minimal, but the Ayrshire cows tended to show more significant effects than the Friesians, except in the milk cell counts, where the difference was higher in the Friesians.     

Behavioural signs of oestrus during pregnancy in lactating dairy cows

Abstract

Two herds of approximately 50 dairy cows were observed for oestrous behaviour for 6 weeks, 12 times a day for 30 minutes. It appeared that 3.08% of the pregnant cows showed oestrous behaviour during pregnancy (EBP) in such an intensity that they would have been considered in oestrus. With a less rigid oestrus detection threshold, 10.8% of the pregnant cows would have been considered to be in oestrus. Animals showed EBP during all months of pregnancy, but most of the behavior was observed in the middle of the gestation period.     

Quantifying characteristics of information-technology applications based on expert knowledge for detection of oestrus and mastitis in dairy cows

Expert opinions were elicited about the characteristics at the commercial-farm level of on-line information technology (IT) applications that are able to detect oestrus and mastitis in dairy cows. Since actual data of these characteristics are not available, judgmental data provided an alternative means to interpret the implications of research results for commercial farms. Applications included were activity measurement, milk-production measurement, electrical conductivity of quarter milk, automated concentrate feeders and milk-temperature measurement. Sensitivity and specificity of detection of oestrus (OD), clinical-mastitis (CMD) and subclinical-mastitis (SCMD) were ascertained. Conjoint-analysis was used to assess the effect of each application indirectly by decomposing the evaluated overall detection characteristics of a predefined number of IT combinations.

The individual experts were consistent in evaluating the alternatives, but there was variation in estimates among experts. Estimations of the main effects of the applications and important first-order interactions were incorporated into the detection models. Implementation of all applications under study resulted in overall sensitivities and specificities of 82% and 90%, 73% and 87%, 58% and 82% for OD, CMD and SCMD, respectively. Further research is necessary that should take into account costs and benefits of the different detection systems based on the current status of farm performance (e.g. OD and mastitis incidence) and farm structure (e.g. farm size, years in operation of the milking parlour and parlour layout). Research to do this is currently in progress.     

Gene expression patterns in the ventral tegmental area relate to oestrus behaviour in high-producing dairy cows

Reduced oestrus behaviour expression or its absence (silent oestrus) results in subfertility in high-producing dairy cows. Insight into the genomic regulation of oestrus behaviour is likely to help alleviate reproduction problems. Here, gene expression was recorded in the ventral tegmental area (VTA) of high milk production dairy cows differing in the degree of showing oestrus behaviour (H - highly expressing versus L - lowly expressing), which was then analysed. Genes regulating cell morphology and adhesion or coding for immunoglobulin G (IgG) chains were differentially expressed in VTA between cows around day 0 and 12 of the oestrus cycle, but only in cows that earlier in life tended to show high levels of oestrus behaviour (H0 versus H12). The comparisons between H and L groups of cows also revealed differential expression of several genes (e.g. those of the IgG family or encoding for pro-melanin-concentrating hormone). However, any significant changes in VTA genes expression were detected in the comparison of L0 versus L12 cows. Altogether, the genes expression profile in VTA of cows highly expressing oestrus behaviour changes together with phases of the oestrus cycle, while in case of cows expressing oestrus behaviour lowly it remains stable. This supports the existence of genomic regulation by centrally expressed genes on the expression of oestrus behaviour in dairy cows.     

奶牛发情行为的监测研究现状及进展

为了适应较大规模、集约化奶牛养殖的需求,提高奶牛的繁殖率和奶牛场的经济效益,本文就国内外奶牛发情行为监测的方法进行了评述。人工观察监测奶牛发情的方法耗时长,工作量大,而且对于夜间发情奶牛的适用性受限制,会出现较大比例的漏检等弊端;数字化检测方法日益发展,在提高工作效率的同时也增加了经济效益,但是部分数字化监测方法不够完善和成熟,例如,接触式测量会影响奶牛的发育。因此,需要进一步统计准确的数据,通过非接触式的检测装置及技术判定奶牛的发情行为。     

Comparison of oestrus detection methods in dairy cattle

Sixty-seven Holstein-Friesian cows, from 20 days postpartum, were recruited into the study and fitted with both a pedometer (SAE Afikim) and a Heatime neck collar (SCR Engineers) and allocated a heat mount detector (either scratchcard [Dairymac] or KaMaR [KaMaR]) or left with none, relying only on farm staff observation. Common production stressors and other factors were assessed to determine their impact on the ability of each method to accurately detect oestrus and to investigate effects on the frequency of false-positive detections. Only 74 per cent of all potential oestrus periods (episodes of low progesterone) were identified by combining information from all methods. There was no difference between the methods in terms of sensitivity for detecting 'true oestrus events' (approximately 60 per cent), with the exception of scratchcards, which were less efficient (36 per cent). Pedometers and KaMaRs had higher numbers of false-positive identifications. No production stressors had any consequence on false-positives. The positive predictive values for neck collars or observation by farm staff were higher than those of other methods, and combining these two methods yielded the best results. Neck collars did not detect any of the nine oestrus events occurring in three cows with a body condition score (BCS) of less than 2, and the efficiency of correctly identifying oestrus was also reduced by high milk yield (odds ratio [OR]=0.34). Pedometer efficiency was reduced by lameness, low BCS or high milk yield (OR=0.42, 0.15 or 0.30, respectively).     

Detecting oestrus by measuring milk temperatures of dairy cows during milking

An experiment was set up primarily to investigate whether the milk temperature in the clawpiece of the milking machine corresponds with the body temperature of the cow. On average the milk temperature was slightly lower (0.09°C) than the rectal temperature. There were, however, some differences between cows. Secondly it was investigated whether measuring the milk temperature twice a day may be of use for detecting sick cows and cows on heat. During the observation period, however, there were no sick cows. In total there were 19 cases of oestrus. In 16 cases there was an increase of ≥ 0.3°C compared with the mean morning or evening temperature of the preceding days.Measuring the temperature in the clawpiece during milking may open up prospects for an automated system to identify cows which are on heat or sick.