Parity Cows Research Articles

Relationship between milk somatic cell count and postpartum ovarian cyclicity and fertility in dairy cows

The main objective of the study was to describe the relationship of high somatic cell count (SCC) with the incidence of abnormal postpartum resumption of ovarian cyclicity and reproductive performance in dairy cows. The factors influencing SCC were also investigated. Four hundred and forty-seven cows from six dairy herds in Japan were monitored for SCC and postpartum resumption of ovarian cyclicity. Cows with high SCC (200,000 to 500,000) had a higher incidence of prolonged luteal phase (P < 0.01) than cows with an SCC of 50,000 to 100,000. The high SCC cows (> 500,000) also showed a higher incidence of delayed first ovulation post partum than cows with an SCC ≤500,000 (P < 0.05) during the first month post partum. Cows with an SCC of 200,000 to 500,000 showed lower conception and pregnancy rates, and more days from calving to conception than cows with an SCC of less than 200,000 (P < 0.05). Cows in parity 5 or more had a higher incidence of high SCC than cows in the first and second parities (P < 0.05). It is concluded that cows with a high SCC have a higher incidence of abnormal postpartum resumption of ovarian cyclicity, leading to reduced reproductive performance.

English

The objective of the study is to establish the effect of parity on milk composition and fatty acid profiles of Nguni cattle milk. Forty-four Nguni cows with parities ranging from 1 to 13 were included in this study. The cows were grouped to three parity groups: parity group 1 (parity 1 to 5), parity group 2 (parity 6 to 9) and parity group 3 (parity 10 to 13). Samples of the milk were collected in a single day and the milk was analyzed using gas chromatography. Parity had no effect of proximate composition (fat, DMC and moisture %) on milk. The fatty acids (FA) present in the milk of the three parity groups were primarily palmitic (33.3 to 40.5%), oleic (16.3 to 20.3%), myristic (12.5 to 13.2%) and stearic (10.8 to 11.7%) acids, in decreasing order of proportion. Milk from parity group 3 cows contained significantly (p < 0.05) higher proportions of butyric, myristoleic, oleic, eicosenoic, conjugated linoleic acid (CLA), arachidonic and eicosopentaenoic acids when compared with the other two parity groups. Parity group 3 also had significantly (p < 0.05) higher values for total SFA, MUFA, PUFA, omega 3 fatty acids and n-6/n-3 ratio than the other two parity groups. Cows in higher parities generally have higher values for individual fatty acids when compared to those in lower parities. Parity is therefore, an important factor that must be considered when assessing milk quality in Nguni cows. Key words: Conjugated linoleic acid, fat content, harsh environment, fatty acid profile, milk composition.

Cow Effects and Estimation of Success of First and Following Inseminations in Dutch Dairy Cows

The objective of this research was to determine the contribution of cow factors to the probability of successful insemination accounting for the serial number of inseminations in analysis. The investigation was performed with 101,297 insemination records in 51,525 lactations of different cows from 1368 herds obtained from the Dutch milk production recording database. Cows that had a first insemination (AI) between 40 and 150 days post-partum with one or more inseminations (≤6 inseminations) were selected. An insemination was defined successful when not followed by another insemination and when the cow calved between 267 and 295 days after insemination, or when the cow was culled between 135 and 295 days after the last insemination. Breed, parity, days in milk, lactation curve characteristics, milk production traits, moment of AI related to peak milk yield time (before or after peak milk yield), the last calf (female, male, twin or stillbirth) and season of insemination were selected as independent parameters for a model with successful rate of insemination as dependent parameter. A multivariable logistic regression model was used within cow and farm as a random effect. The probability of successful insemination was the highest in the first insemination and decreased in the following inseminations. However, the success rate of all inseminations increased in a later stage of lactation. The improvement in the successful inseminations in a later stage of lactation was better in multiparous cows than in first parity cows. Insemination in summer and before peak milk yield time reduced the success of insemination. The success rate was the lowest in 100% Holstein Friesian cows compared with other breeds and was the highest when the last calf was a female calf compared to a male calf, twin or stillbirth. In conclusion, the success of first and following inseminations depended on parity, breed, season of insemination, last calf status, daily milk yield at insemination date, serial insemination number and days in milk at insemination date.

Effect of short-term cooling on physiological and productive responses of primiparous Holstein cows exposed to elevated ambient temperatures

To evaluate effects of short periods of cooling on physiological and productive parameters during summer, 27 first parity cows were grouped into control, 1 h cooling (C); 2 h cooling (AM); and 4 h cooling (AM+PM). The cooling system consisted of misting and forced ventilation. Skin temperatures were lower (P<0.05) in the AM+PM group during the morning but higher (P<0.01) in the afternoon, compared to C and AM groups. The respiratory rate was lower (P<0.01) in the AM+PM group than in C and AM groups. Rectal temperature, milk production, milk protein, and milk energy output were similar among the groups. Conversely, milk fat was higher (P<0.05) in AM+PM cows. Because use of a 4 h cooling period enhanced some physiological parameters and milk fat in primiparous Holstein cows, we recommend increasing the cooling period in arid regions to achieve higher performance and comfort of dairy cows.

Randomized clinical trial of antibiotic and prostaglandin treatments for uterine health and reproductive performance in dairy cows

The objectives of this study were to assess the efficacy of antibiotic treatment for preventing postpartum uterine disease among cows at high risk of uterine disease, and to assess the efficacy of PGF2α for treating cytological endometritis (CYTO) and purulent vaginal discharge (PVD). A total of 2,178 Holstein cows in 6 herds were enrolled in a randomized clinical trial. Within 24h after parturition, cows were classified at being at high risk of uterine disease (HRUD; n=1,017) if they had twins, dystocia, or retained placenta. All remaining cows were classified as being at low risk of uterine disease (LRUD; n=1,161). Cows in the HRUD group were randomly allocated in a factorial design to receive ceftiofur crystalline free acid (CCFA) at 24h after parturition or be untreated, and to receive dinoprost (PGF2α) at 35 and 49 (±3) days in milk (DIM) or to be untreated. Cows in LRUD were randomly allocated to receive PGF2α at 35 and 49 (±3) DIM or to be untreated. Serum progesterone was measured at 21, 35, 49, and 63 (±3) DIM. Cows were examined at 35 (±3; exam 1) and 56 (±3; exam 2) DIM for CYTO (by cytobrush device; ≥6% polymorphonuclear cells in endometrial cytology) and for PVD (by Metricheck device; mucopurulent or purulent vaginal discharge). Statistical analyses were performed using multivariable logistic regression models accounting for herd clustering. Treatment with CCFA in HRUD cows was not associated with the probability of metritis overall, but interactions occurred such that CCFA decreased the incidence of metritis among HRUD cows that did not have retained placenta and among cows of parity ≥2. Treatment with CCFA in HRUD cows decreased the probability of PVD at exam 1. Treatment with PGF2α did not affect the probability of cure of CYTO or PVD irrespective of progesterone concentration at the time of treatment. Among cows affected by CYTO or PVD at exam 1, 66 and 63%, respectively, had spontaneously cured at exam 2. Cows persistently affected at exam 2 had an increased time to pregnancy and were more likely to have both CYTO and PVD at exam 1. Administration of PGF2α at both 5 and 7 wk postpartum did not mitigate the effects of CYTO or PVD on reproductive performance. Clinical approaches to treatment of chronic postpartum reproductive tract infection and inflammation should be reassessed.

Short communication: Best prediction of 305-day lactation yields with regional and seasonal effects

In the United States, lactation yields are calculated using best prediction (BP), a method in which test-day (TD) data are compared with breed- and parity-specific herd lactation curves that do not account for differences among regions of the country or seasons of calving. Complete data from 538,090 lactations of 348,123 Holstein cows with lactation lengths between 250 and 500 d, records made in a single herd, at least 5 reported TD, and twice-daily milking were extracted from the national dairy database and used to construct regional and seasonal lactation curves. Herds were assigned to 1 of 7 regions of the country, individual lactations were assigned to 3-mo seasons of calving, and lactation curves for milk, fat, and protein yields were estimated by parity group for regions, seasons, and seasons within regions. Multiplicative pre-adjustment factors (MF) also were computed. The resulting lactation curves and MF were tested on a validation data set of 891,806 lactations from 400,000 Holstein cows sampled at random from the national dairy database. Mature-equivalent milk, fat, and protein yields were calculated using the standard and adjusted curves and MF, and differences between 305-d mature-equivalent yields were tested for significance. Yields calculated using 50-d intervals from 50 to 250 d in milk (DIM) and using all TD to 500 DIM allowed comparisons of predictions for records in progress (RIP). Differences in mature-equivalent milk ranged from 0 to 51kg and were slightly larger for first-parity than for later parity cows. Milk and components yields did not differ significantly in any case. Correlations of yields for 50-d intervals with those using all TD were similar across analyses. Yields for RIP were slightly more accurate when adjusted for regional and seasonal differences.

Layouts for small freestall dairy barns: Effect on milk yield for cows in different parities

Freestall housing for dairy cows has many different layouts and the space allocated for cows differs considerably. The objective of the present study was to investigate possible associations between barn layout and milk yield for different parities in small dairy freestall barns. Layouts of 204 Norwegian freestall barns constructed during the period from 1995 to 2005, and with a mean herd size of 42.7±15.5 cows, were obtained and merged with milk yield data and calving interval, for each parity, from the Norwegian Milk Recording System (NDHRS). The milk yield data set contained 20,221 different lactations from these 204 herds. Both simple mixed models, including the different explanatory variables one by one together with parity, calving interval, and herd as random effect, and a final mixed model, including all significant explanatory variables, were created. According to variables tested in this study, the final mixed model estimates show that only primiparous cows benefit significantly from increased free space allocation. Milk yield was generally higher in automatic milking system barns compared with that in barns with milking parlors, but not for primiparous cows. Milk yield was higher for all parities for barns using separation pens in accordance with the recommendations. Barns with 2 or more dead-end alleys had lower milk yield compared with that from layouts without dead-end alleys. Primiparous cows benefited from water troughs located for easy access and responded with increased milk yield. In 10% of the barns, the water trough capacity was less than 47% of the recommendations, and all parities benefited from a water trough capacity higher than this level. Higher parities had increased milk yield when water trough capacity was more than 80%. Feed bunk space, number of freestall rows, and the location of freestalls had no significant effect on the milk yield. The present study showed that increased space and improved access to water is beneficial to primiparous cows, whereas layouts without dead-end alleys and improved water capacity is beneficial for all cows in freestall systems.

Identifying risk factors for poor hind limb cleanliness in Danish loose-housed dairy cows

The objective of this study was to identify possible risk factors for poor cow hind limb cleanliness in Danish loose-housed, lactating dairy cows. The study was conducted as a cross-sectional study of 1315 cows in 42 commercial Danish dairy herds with primarily Danish Holstein cows. The effect of four cow-level factors (parity, days in milk, daily lying time and lameness) and eight herd-level factors (herd size, milk production, milking system, floor type, access to pasture grazing, floor scraping frequency, hoof bathing frequency and hoof washing frequency) on the risk of having dirtier hind limbs were analysed using ordinal logistic regression fitting a proportional odds model. Cow hind limb cleanliness was scored using an ordinal score from 1 to 4: 1 being clean and 4 being covered in dirt. The odds ratios (ORs) estimated from the proportional odds model depict the effect of a risk factor on the odds of having a higher rather than a lower cleanliness score. First parity cows had an increased risk of being dirtier compared with third parity or older cows (OR = 1.70). Compared with late lactation, early and mid lactation were associated with an increased risk of being dirtier (OR = 2.07 and 1.33, respectively). Decreasing the daily time lying by 30 min was associated with an increased risk of being dirtier (OR = 1.05). Furthermore, an increased risk of being dirtier was found in herds with no pasture access (OR = 3.75).

Different humoral mechanisms against Neospora caninum infection in purebreed and crossbreed beef/dairy cattle pregnancies

The antigen-specific IgG subclass response may be a convenient indicator of the underlying nature of T helper cell regulation. The aim of the present study was to identify possible differences in Neospora caninum-specific total plasma IgG, IgG1 and IgG2 antibody levels in purebreed and crossbreed pregnancies throughout gestation in beef and dairy cattle chronically infected with N. caninum. Comparisons were also made between aborting and non-aborting dams. The population examined comprised 96 pregnant parous cows seropositive for N. caninum. Plasma antibodies were determined on Days 90, 120, 150, 180 and 210 of gestation or until abortion. Of the 96 pregnancies examined, 12 ended in abortion. None of the 14 Holstein-Friesian (HF) cows inseminated with HF semen (HF–HF group) aborted, whereas 6 (11.0%) of the 54 HF cows inseminated with Limousin semen (HF-L group) and 6 (21.4%) of the 28 Rubia Gallega (RG) beef cows inseminated with RG semen (RG–RG group) aborted. In the 84 non-aborting cows, a significant positive effect of gestation day was observed on total IgG, IgG1 and IgG2 antibodies levels (P<0.0001 for the three variables). In RG–RG cows, significantly higher levels of IgG (P=0.003; d.f.=2; F-value=6.41), IgG1 (P<0.001; d.f.=2; F-value=10.55) and IgG2 (P=0.004; d.f.=2; F-value=5.82) antibodies against N. caninum were recorded throughout gestation compared to the other groups, whereas the levels of these antibodies were significantly lower in HF–HF on Days 180 and 210 of gestation. In aborting cows, significantly lower IgG (P=0.001; d.f.=1; F-value=25.21) and IgG2 (P=0.001; d.f.=1; F-value=20.39) antibody levels were observed in the RG–RG cows compared to the HF-L cows, whereas no significant effect on IgG1 antibody levels was detected in the two groups with aborting animals (RG–RG and HF-L). Our findings indicate that humoral mechanisms against N. caninum infection and abortion differ in purebreed pregnancies and crossbreed pregnancies in beef/dairy cattle.

Risk factors associated with cystic ovarian disease in Norwegian dairy cattle

BackgroundThe aims of this study were to establish the incidence of cystic ovarian disease (COD) and its geographical and seasonal variation in Norway, investigate the effect of COD on culling rates, and describe the effects of COD on subsequent reproductive performance and its association to twins.MethodsDiagnosis of COD was made by veterinary surgeons in the field. Four statistical models were made all including herd as random effect: The four different dependent variables investigated were: 1) Diagnosis of COD between 40 and 165 days in milk or not; (n = 511,657); 2) Twins or singleton; data restricted to lactations with new calving (n = 156,661): 3) Culling/removal or not (n = 573,184): 4) Culling due to reproductive problems; data included only lactations which ended in culling (n = 234,232). Model 1, 3 and 4 applied Cox regression models, and model 2 logistic regression. Independent variables were parity, twins/singletons, calving season, herd size, region, COD occurrence in present lactation (if not dependent), and COD diagnosis in previous lactation.ResultsThe incidence was 0.82% per lactation. COD increased with increasing parity, was smallest at herd size between 35 and 85 cows. Cows in 1st parity and calved in spring had lowest hazard of COD and hazard for COD diagnosis was highest in autumn with HR = 2.6 (1.9 - 3.4) compared to spring. There was an interaction between parity and season. COD incidence was lower south of 60°N. Cows which experienced COD had an increased odds of giving birth to twins OR = 2.2 (1.7 - 2.7). Of those that were culled, those with COD were culled more frequently because of reproductive problems; HR = 2.1 (1.9 - 2.3) for higher parity than 2. Having COD diagnosed in the preceding lactation was a hazard for diagnosis in the lactation studied.ConclusionCOD diagnosis is strongly associated with season (autumn calving) and parity. Herds north of 60°N have more COD. Occurrence of COD is associated with twin births as well as culling due to reproduction.

Effect of milk yield characteristics, breed, and parity on success of the first insemination in Dutch dairy cows

The objective of this study was to determine the contribution of cow factors to the probability of a successful first insemination (SFI). The investigation was performed with 51,791 lactations from 1,396 herds obtained from the Dutch dairy cow database of the Cattle Improvement Co-operative (CRV). Cows that had the first insemination (AI) between 40 and 150 d postpartum were selected. The first AI was classified as successful when cows were not reinseminated and either calved between 267 and 295 d later or were culled within 135 to 295 d after first AI. The lactation curve characteristics of individual lactations were estimated by Wilmink's curve using the test-day milk records from CRV. The lactation curve characteristics (peak milk yield, milk yield at the first-AI date, time of peak yield (PT), and milk persistency) were calculated. Breed, parity, interval from calving to first AI (CFI), lactation curve characteristics, milk production traits, moment of AI related to PT (before or after PT), calf status, month of AI, and month of calving were selected as independent variables for a model with SFI as a dependent variable. A multivariable logistic regression model was used with farm as a random effect. Overall SFI was 44%. The effect of parity on SFI depended on CFI. The first-parity cows had the greatest SFI (0.43) compared with other parities (0.32–0.39) at the same period of CFI before 60 d in milk (DIM), and cows in parity ≥5 had the least SFI (0.38–0.40) when AI was after 60 DIM. After 60 DIM, extending CFI did not improve SFI in the first-parity cows, but SFI was improved in multiparous cows. Holstein-Friesian cows had lesser SFI (0.37) compared with cross-breed cows (0.39–0.46). Twin and stillbirth calving reduced SFI (0.39) compared with a single female calf (0.45) or a male calf (0.43) calving. The SFI in different months of AI varied and depended on CFI. Cows that received AI before 60 DIM had a lesser SFI, especially in March, June, and July (0.18, 0.35, and 0.34, respectively). Artificial insemination before PT reduced SFI (0.39) in comparison with AI after PT (0.44). The effect of milk yield at the first-AI date on SFI varied depending on CFI. After 60 DIM at the same period of CFI, a high level of milk yield at the first-AI date reduced SFI. In conclusion, knowledge of the contribution of cow factors on SFI can be applied to support decision making on the moment of insemination of an individual cow in estrus.

The effect of season on aspects of in vitro embryo production in sub-fertile beef cows

This study was conducted to investigate the possible effect of season onin vitro embryo production (IVEP) in sub-fertile beef cows. Forty beef (40) cows of different breeds and parities were used in a trial conducted as part of a commercial embryo production programme. Animals were subjected to a once a week ultrasound guided oocyte recovery procedure (OPU) and all oocytes were entered in a commercial IVEP programme. A significant difference in follicular populations could be established for different months of the year. As for recovery rate, oocyte quality and embryo production, no significant differences could be established. However, the embryo production per OPU session per cow showed a definite seasonal pattern with low production during hotter months, a steady increase during the colder months and a peak in spring. This information should be helpful in the future planning of IVEP programmes for fertility-impaired cows.

Variations in feeding behaviour of high-yielding dairy cows in relation to parity during early to peak lactation

Abstract. The objective of this study was to compare the feeding behaviour of high-yielding dairy cows in relation to parity during early to peak lactation and to determine whether or not there was any relationship between variables describing their feeding behaviour and total feed intake. Information concerning feed intake of each individual dairy cow is especially valuable for the herd management, particularly in early lactation. However, technical requirements for implementation are rarely given. Therefore, relationships between feed intake and time-related feeding behaviour parameters are of special interest. Time-related parameters could be recorded on farm conditions adapted sensor technology. Seventy high-yielding lactating dairy cows in different parities (23 in the 1st lactation, 17 in the 2nd lactation, and 30 in the 3rd-and-more-lactation) with an average of 11 000 kg milk yield per year were fed using automatic feeders from the 2nd to the 15th week of lactation. 222 231 recorded visits were analysed in three equal periods (period 1 = 7–39, period 2 = 40–72, and period 3 = 73–105 days in milk [DIM]) during early to peak lactation. Visits were clustered in meals based on the estimated meal criterion (28.5 min). The present study yielded the following values for meal frequency, number of visits per meal, meal duration, meal size, daily mealtime, daily dry matter intake (DMI), and feeding rate over the course of the study were 7.61 ± 1.7 (mean ± SD) meals/d, 4.02 ± 1.68 visits/meal, 37.07 ± 13.77 min/meal, 2.96 ± 0.92 kg DM/meal, 272.18 ± 82.14 min/d, 21.46 ± 4.29 kg DM/d, and 85.56 ± 28.77 g DM/min, respectively. Younger cows had more meals per day, more number of visits per meal, longer daily mealtime but a smaller meal size, lower daily DMI, and lower feeding rate compared to older cows (P&lt;0.001). Meal duration and meal size were highly related to the number of visits at feeder per meal (R2=0.55–0.63; P&lt;0.001, R2=0.25–0.39; P&lt;0.001 respectively). In addition, meal size was highly related to meal duration (R2=0.59–0.72; P&lt;0.001). Results from this study, which analysed data based on meal criterion, showed a higher correlation between the selected parameters of feeding behaviour and feed intake. The high correlation between meal duration and meal size could be used to estimate feed intake.

Evaluation of bull fertility in dairy and beef cattle using cow field data

A successful outcome to a given service is a combination of both male and female fertility. Despite this, most national evaluations for fertility are generally confined to female fertility with evaluations for male fertility commonly undertaken by individual breeding organisations and generally not made public. The objective of this study was to define a pertinent male fertility trait for seasonal calving production systems, and to develop a multiple regression mixed model that may be used to evaluate male fertility at a national level. The data included in the study after editing consisted of 361,412 artificial inseminations from 206,683 cow-lactations (134,911 cows) in 2,843 commercial dairy and beef herds. Fixed effects associated with whether a successful pregnancy ensued (pregnant = 1) or not (pregnant = 0) from a given service were year by month of service, day of the week, days since calving, cow parity, level of calving difficulty experienced, whether or not the previous calving was associated with perinatal mortality, and age of the service bull at the date of insemination. Non-additive genetic effects such as heterosis and recombination loss as well as inbreeding level of the service bull, dam or mating were not associated with a successful pregnancy; there was no difference in pregnancy rate between fresh or frozen semen. Random effects included in the model were the additive genetic effect of the cow, as well as a within lactation and across lactation permanent environmental effect of the cow; pedigree group effects based on cow breed were also included via the relationship matrix. Temporal differences in the AI technician and service bull were also included as random effects. A difference in five percentage units in male fertility was evident between the average effects of different dairy and beef breeds. The correlation between raw pregnancy rates for bulls with more than 100 services (n = 431) and service bull solutions from the mixed model analysis was 0.66. The correlation between the raw pregnancy rates of 288 technicians with more than 100 services and their respective solutions from the mixed model was 0.35. These low to moderate correlations suggest considerable re-ranking among both service bulls and technicians and suggest possibly a benefit of using a statistical model to better estimate the performance of both service bulls and technicians.

Dystocia in Friesian cows and its effects on postpartum reproductive performance and milk production

A total of 1,243 records for 585 dairy Friesian cows from 1997–2004 were used to study the factors affecting dystocia and its effects on reproductive performance and milk production. The overall incidence of dystocia was 6.9%. The percentage of dystocia decreased with increasing live body weight, age, and parity of cows (P < 0.05); however, it increased with increasing birth weight of calves (P < 0.05). The highest percentage of dystocia was detected in winter season, but the least percentage was in summer season (P < 0.05). The percentage of incidence of dystocia was significantly (P < 0.05) higher with winter feeding compared to summer ration (8.2% vs. 5.1%). The percentage of incidence of dystocia was significantly (P < 0.05) higher with twinning than single calving (15.5% vs. 6.5%), while not significantly affected by the sex of born calves. Incidence of dystocia had adverse effects on reproductive performance and milk yield. The service interval, service period, days open, and calving interval were significantly (P < 0.05) longer in cows afflicted with dystocia compared to normal cows. The conception rate was lower (P < 0.05), but the number of service per conception was higher (P < 0.05) in cows afflicted with dystocia compared to normal cows (60.5% vs. 73.0% and 3.4 vs. 2.7, respectively). Average daily milk yield was lower (P < 0.05) by 1 kg for cows with incidence of dystocia compared to normal cows.

Peripheral white blood cell counts throughout pregnancy in non-aborting Neospora caninum-seronegative and seropositive high-producing dairy cows in a Holstein Friesian herd

Pregnancy is characterized by transient changes in the maternal immune system, also evident at peripheral level. The present study analyzes the kinetics and possible factors affecting peripheral white blood cell populations throughout pregnancy in a herd of high-producing dairy cows chronically infected or not with Neospora caninum. We examined 54 pregnant parous cows: 29 Neospora-seronegative and 25 Neospora-seropositive cows. Blood samples were collected on Days 90, 120, 150, 180 and 210 of gestation. General Linear Model (GLM) repeated measures analysis of variance showed that the interaction Neospora-seropositivity × parity significantly affected total leukocyte, neutrophil and monocyte counts with lower levels of total leukocytes, lower neutrophil and higher monocyte counts recorded in primiparous Neospora-seropositive cows. In addition, N. caninum-seropositive cows had significantly increased monocyte counts on Day 180 of gestation compared to seronegative ones. Other factors significantly associated with changes in total and/or differential leukocyte profiles were period of pregnancy, season, twin pregnancy and milk production. In conclusion, a parity-associated effect of chronic N. caninum infection was observed on peripheral blood cell profiles in dairy cattle during gestation.

Prevalence, risk factors for and impact of subclinical endometritis in repeat breeder dairy cows

The aim of this study was to determine the prevalence and risk factors for subclinical endometritis (SE) and its effects on fertility in repeat breeder dairy cows. Dairy cows of parity 1 to 5 that were artificially inseminated (AI) 3 or more times (selected cows were artificially inseminated an average of 3.9 times) were examined at 190 ± 40 days in milk, and clinically normal cows (n = 77) were selected based on the absence of abnormal discharges on external inspection and the absence of abnormal findings on transrectal palpation and ultrasonographic examination. Endometrial samples were collected from the uterus by using the lavage technique in the luteal phase of the estrus cycle. Collected samples were centrifuged and a drop of sediment was streaked on to a clean microscopic slide and stained with Giemsa. The percentage of polymorphonuclear cells (neutrophils) was counted for each specimen. The analysed data showed that the average amount of neutrophils was 3.1% (0–9) in the selected cows. Abnormal calving (dystocia, twin births, and abortion), retained placenta, and postpartum uterine infections were associated with an increase in prevalence of SE. Subsequently, SE was significantly associated with a decrease in conception rate in the next AI. Conception rate in the next AI was 5% for cows (n = 38) with SE (≥ 3% neutrophil), and 47% for cows (n = 34) without SE (< 3% neutrophil) (P = 0.001). The prevalence of cytologically diagnosed SE (≥ 3% neutrophil) was 52.7% (n = 38). In conclusion, abnormal calving, retained placenta, and postpartum uterine infections may be associated with an increase in prevalence of SE and subsequently, SE may decrease reproductive performance and increase the incidence of repeat breeder syndrome.

Predicting energy × protein interaction on milk yield and milk composition in dairy cows

Feed management is one of the principal levers by which the production and composition of milk by dairy cows can be modulated in the short term. The response of milk yield and milk composition to variations in either energy or protein supplies is well known. However, in practice, dietary supplies of energy and protein vary simultaneously, and their interaction is still not well understood. The objective of this trial was to determine whether energy and protein interacted in their effects on milk production and milk composition and whether the response to changes in the diets depended on the parity and potential production of cows. From the results, a model was built to predict the response of milk yield and milk composition to simultaneous variations in energy and protein supplies relative to requirements of cows. Nine treatments, defined by their energy and protein supplies, were applied to 48 cows divided into 4 homogeneous groups (primiparous or multiparous × high or low milk potential) over three 4-wk periods. The control treatment was calculated to cover the predicted requirements of the group of cows in the middle of the trial and was applied to each cow. The other 8 treatments corresponded to fixed supplies of energy and protein, higher or lower than those of the control treatment. The results highlighted a significant energy × protein interaction not only on milk yield but also on protein content and yield. The response of milk yield to energy supply was zero with a negative protein balance and increased with protein supply equal to or higher than requirements. The response of milk yield to changes in the diet was greater for cows with high production potential than for those with low production potential, and the response of milk protein content was higher for primiparous cows than for multiparous cows. The model for the response of milk yield, protein yield, and protein content obtained in this trial made it possible to predict more accurately the variations in production and composition of milk relative to the potential of the cow because of changes in diet composition. In addition, the interaction obtained was in line with a response corresponding to the more limiting of 2 factors: energy or protein.

Risk factors for abortion in dairy cows from commercial Holstein dairy herds in the Tehran region

In last decade, pregnancy loss in dairy cattle has had an upward trend bringing difficulties for breeders: the annual cost is estimated around 396 billion Rials (i.e. around 40 million US$) for the Iranian dairy industry. The present study was conducted to determine the influence of maternal factors on abortion and to predict the probability of abortion as well as the effect of these factors on the fetal lifetime in Holstein dairy cattle. Data from 44,629 established pregnancies that included 14,226 heifers and 30,403 pregnancies from 12,265 parous cows in nine industrial dairy herds around Tehran were used. Overall, 4871 pregnancies of parous cows resulted in abortion. Prediction of the probability of abortion (PPA) was estimated by a logistic regression model. Survival analysis was performed using an accelerated failure time (AFT) model assuming a multi-modal hazard function. Effective factors included age of dam at conception, gravidity, open days, number of previous abortion(s), abortion before/after 60 days of gestation in previous conception, herd and season of insemination. The PPA decreased with increasing open days, increasing gravidity and no previous abortion. In addition, the PPA was greater for cows which had been inseminated during summer versus winter. However, the difference between autumn and spring was not significant. Overall, 25 sires out of 695 from which sperm was collected for artificial insemination (AI) had significantly higher risk of abortion, with odds ratios ranging between 1.44 and 4.73 compared to the average. The survival probability increased slightly during gestation as gravidity increased for cows that had a previous abortion. Cows that had aborted before 60 days of gestation in previous conception tended to abort later in their next conceptions.

Feed intake and production parameters of lactating crossbred cows fed maize-based diets of stover, silage or quality protein silage

Thirty-six Boran × Friesian dairy cows (392 ± 12 kg; mean ± SD) in early parity were used in a randomised complete block design. Cows were blocked by parity into three blocks of 12 animals and offered normal maize (NM) stover (T1), NM silage (T2) or quality protein maize (QPM) silage (T3) basal diets supplemented with a similar concentrate mix. Feed intake, body weight and condition changes and milk yield and composition were assessed. The daily intake of DM, OM, NDF and ADF for cows fed the NM stover-based diet was higher (P < 0.05) than for the cows fed the NM silage and QPM silage-based diets. However, the daily intake of DOM (9.3 kg) and ME (140.8 MJ) for cows on QPM silage-based diet was higher (P < 0.05) than for cows on NM stover-based diet (8.4 kg and 124.2 MJ) and NM silage-based diet (7.9 kg and 119.1 MJ). Body weight of cows was affected (P < 0.05) by the diet, but diet had no effect (P > 0.05) on body condition score, milk yield and milk composition. The digestible organic matter in the NM stover-based diet (724 g/kg DM) was lower (P < 0.05) than that in the NM (770 g/kg DM) and QPM silage-based diet (762 g/kg DM). It was concluded that the performances of the cows on the NM silage and QPM silage diets were similar and were not superior to that of the NM stover-based diet.