Primiparous Cows Research Articles

Performance and metabolic evaluation in primiparous beef cows under grazing at different breeding ages.

We aimed to evaluate the metabolic and performance differences in primiparous Nellore cows, which became pregnant at 14 or 24-mo old. Thirty-eight cows with 202 ± 5 days of gestation were divided into two treatments according to breeding age: 14 or 24-mo. Cows were evaluated for body weight (BW), body condition score (BCS), carcass characteristics, milk yield, calves's performance, and blood characteristics. The animals were managed in eight paddocks under continuous grazing and evaluated from 90 d before parturition until 240 d after calving. We observed an interaction between breeding age and time (P < 0.01) for cow BW. Both breeding age categories experienced BW loss during parturition, with a concurrent decrease in BCS. However, following their first calving, the BW of 24-mo cows remained stable (P > 0.05), whereas 14-mo cows exhibited a gradual recovery in BW after parturition (P < 0.05). Milk yield was greater in 24-mo animals (P < 0.01), but decreased with increasing milking days (p < 0.05) for both groups. The weight gain calves from the heifers bred at 24-mo was greater (P < 0.01), which reflected in greater BW at weaning. The beta-hydroxybutyrate (β-OHB) concentration was greater before calving and a marked decrease after parturition (P < 0.05). The 24-mo cows had greater blood β-OHB (P < 0.01) at prepartum and 30 days after calving. Blood progesterone was greater in 24-mo cows (P > 0.05). Primiparous beef cows that conceive at either 14 or 24-months of age exhibit distinct nutritional requirements and metabolic profiles. Notably, cows that conceive at 24-months of age have the advantage of weaning heavier calves and displaying a more consistent reproductive cycle following their first calving than cows that conceive at 14-months.

Association between non-esterified fatty acids and calcium concentrations at calving with early lactation clinical diseases, fertility and culling in grazing dairy cows in Uruguay

This study describes the association of non-esterified fatty acids (NEFA) and calcium concentrations at calving with early lactation disease, reproductive performance and culling in 646 dairy cows from 13 commercial grazing dairy herds in Uruguay. During one year, health events were recorded from calving to 30 days in milk (DIM). The first author visited each farm every 20 days. During each visit, body condition score (BCS) was recorded (scale 1–5), defining BCS < 3 as suboptimal and BCS > 3 as optimal, and a blood sample was taken from cows between 0 and 4 DIM for metabolite determination. To evaluate the association between health events (i.e., retained placenta-metritis and clinical mastitis) and risk factors (parity, BCS, high NEFA (> 0.6 mmol/L) and subclinical hypocalcemia (SCH) (< 2.10 mM)) data were analysed using multivariable logistic regression models. To evaluate the association of health events and risk factors with reproductive performance and culling, data were analysed using Cox proportional hazard regression models. A risk factor and an outcome of interest were assumed to be associated at P < 0.05 and a tendency to be associated was defined at P < 0.10. Overall, 47 % (n = 303) of the cows showed elevated NEFA concentration and 77 % (n = 499) had SCH. In addition, 21.5 % (n = 139) of the cows recorded at least one clinical disease. Cumulative incidence was 17 % (n = 109) for clinical mastitis, 4.2 % (n = 27) for retained placenta (RP)-metritis and 1.4 % (n = 7) for lameness. Clinical mastitis was associated with parity, with lower odds in primiparous (PP) cows (OR = 0.42, P < 0.01). Cows in an optimal BCS also tended to have lower odds (OR = 0.66, P = 0.07). Moreover, high NEFA and SCH cows had higher odds of CM (OR = 4.5, P = 0.01 and OR = 1.75, P = 0.04, respectively). Retained placenta-metritis tended to be associated with high NEFA concentration (OR = 2.2, P = 0.06). Primiparous cows with suboptimal BCS showed an increased first insemination rate (HR = 2.34; P < 0.01). The risk of culling was lower in PP cows (HR = 0.19; P < 0.01) and in cows with optimal BCS and low NEFA concentration (HR = 0.38; P = 0.03). Our data show that metabolic challenge (defined as peripartum suboptimal BCS, high NEFA or SCH) is associated with increased odds of clinical mastitis and RP-metritis, decreased probability of insemination and increased hazard of culling. Under grazing conditions, we suggest that farm management to improve the metabolic adaptation to lactation represents an opportunity to enhance cow performance in terms of health, fertility and longevity.

Metabolic and hormonal profiles and productive performance in primiparous and multiparous cows grazing different forage allowance in late gestation

The aim of this study was to evaluate two levels of forage allowance (FA) during the prepartum period on metabolic, hormonal, productive, and reproductive variables in primiparous (P) and multiparous (M) beef cows. Six weeks before calving, 40 P and 42 M cows were assigned to two FA (native pastures) treatments until calving (day 0): High (15 kg DM/100 BW; H) and Low (5 kg DM/100 BW; L). After calving all cows were managed together. High FA cows presented greater intake than L cows, while M tended to have greater intake than P cows. Increased herbage allowance in late gestation in beef cows successfully improved forage intake and energy balance reflected in body condition score and metabolic and endocrine markers. Also, high forage allowance increased milk yield (5.4 vs 4.6 kg/d, P < 0.05) and calves daily gain rate during the first two months of age (0.88 vs 0.82 kg/d, P < 0.05) in H respect to L cows. Pregnancy rate was greater in H vs L cows (40 vs 28 %, P < 0,05). The endocrine metabolic response to higher forage allowance depended on parity, as primiparous cows showed a greater imbalance around calving. Moreover, most primiparous cows were not pregnant at the end of the breeding season, consistent with their prolonged anestrous. Multiparous cows had better productive and reproductive performance than primiparous cows, showing that growing cows have a pronounced negative energy balance reflected in most of the evaluated parameters.

Effect of suckler cow breed type and parity on the development of the cow-calf bond post-partum and calf passive immunity

BackgroundDevelopment of the cow-calf bond post-partum and passive immunity of calves from spring-calving beef × beef (B×B) and beef × dairy (B×D) cow genotypes was determined using primiparous and multiparous (Experiment 1), and primiparous and second-parity (Experiment 2) animals. In Experiment 1, calves either suckled colostrum naturally (‘natural-suckling’) (n = 126), or were fed colostrum, using an oesophageal-tube (‘artificially-fed’) (n = 26), from their dam within 1-h post-partum. In Experiment 2, all calves (n = 60) were artificially-fed colostrum from their dam. Prior to colostrum suckling/feeding, colostrum was sampled for IgG analysis. The cow-calf bond was assessed using CCTV recordings during the first 4-h post-partum. Calves were blood sampled at 48-h post-partum to determine IgG and total protein (TP) concentrations, and zinc sulphate turbidity (ZST) units.ResultsThere was no difference (P > 0.05) in cow licking behaviours and calf standing and suckling behaviours between the genotypes, except in Experiment 2 where B×D calves had more attempts to suckle before suckling occurred (P ≤ 0.05) compared to B×B calves. In Experiment 1, multiparous cows licked their calves sooner (P ≤ 0.05) and for longer (P < 0.01), and their calves had fewer attempts to stand (P < 0.001), stood for longer (P = 0.05), and had fewer attempts to suckle before suckling occurred (P < 0.001) than primiparous cows; there was no parity effect on cow-calf behaviour in Experiment 2. Colostrum IgG concentrations and measures of calf passive immunity did not differ (P > 0.05) between the genotypes in either Experiment. In Experiment 1, colostrum IgG concentrations were greater (P ≤ 0.05) in multiparous compared to primiparous cows and their calves had superior (P ≤ 0.05) passive immunity; no effect of parity was found in Experiment 2. Passive immunity did not differ (P > 0.05) between suckled and artificially-fed calves in Experiment 1.ConclusionsCow genotype had little effect on cow-calf behaviours, but under ‘natural-suckling’ conditions primiparous cows expressed maternal inexperience and their calves were less vigorous than multiparous cows. Colostrum IgG concentration and calf passive immunity measures were unaffected by genotype, but under ‘natural-suckling’ conditions calves from primiparous cows had lower passive immunity.

Impact of reproductive traits on productive life in Iranian Holstein dairy cows.

Enhancing reproductive performance is a key strategy to mitigate involuntary culling rates, thereby extending productive life (PL) and ultimately improving profitability in dairy cattle herds. A piecewise Weibull proportional hazards model was used to investigate the effect of several important reproductive traits on PL in Holstein dairy cows. Data comprised 200,747 lactation records from 82,505 cows sired by 1952 bulls across 36 dairy herds. PL was defined as the number of days from the first calving to the last milk record or censoring. The statistical model accounted for the time-dependent fixed effects of changes in herd size, year-season, milk production, fat and protein contents, and the time-independent fixed effect of age at first calving. Herd-year and sire effects were also included as random effects. Reproductive traits include calving traits such as calving ease (CE), calf size (CZ), and calf survival (CS), as well as female fertility traits such as number of inseminations per conception (NI), days from calving to first service (CFS), days from first service to conception (FSC), and days open (DO). All reproductive traits had a significant effect on PL (p < 0.001). Each reproductive trait was analysed separately. The relative risk (RR) of being culled increased as the severity of calving difficulties increased in both primiparous and multiparous cows. Cows that calved small or large calves showed a higher risk of being culled compared with those that calved medium size calves. The increased RR of culling was observed only for primiparous cows that gave birth to dead calves. In addition, cows that required more NI, a longer CFS, FSC, and DO had shorter longevity. These insights can deepen our comprehension of the factors affecting PL and provide information for refining management and breeding strategies, which could lead to increased profitability and sustainability in Iranian dairy farming.

Characterization of conception rate after embryo transfer in comparison with that after artificial insemination in dairy cattle

Artificial insemination (AI) and embryo transfer (ET) are important in the reproduction of dairy cows. The conception rate after AI or ET is an essential indicator when selecting appropriate breeding methods. However, information on the environmental factors affecting ET conception rate when compared with AI is limited. We aimed to investigate environmental factors affecting ET conception rate and characterize the differences in environmental factors between AI and ET. Records of the first AI (n = 1,870,143) and ET (n = 29,922) from Holstein nulliparous, primiparous, and multiparous cows in Hokkaido, Japan, were analyzed using separate multivariable logistic regression models. For each breeding method, we grouped primiparous and multiparous cows according to milk yield at peak lactation (PY; < 25, 25-30, 30-35, ≥ 35 kg in primiparous, < 40, 40-45, 45-50, ≥ 50 kg in multiparous) and the interval from calving to first AI or ET (CFI/CFT; < 60, 60-79, 80-99, ≥ 100 d) to evaluate the effects of PY and CFI/CFT on conception rate. AI conception rate decreased with increasing PY in primiparous and multiparous cows, whereas ET conception rate did not decrease significantly. Additionally, the ET conception rate did not decrease even in primiparous and multiparous cows slightly earlier than 60 d in CFI/CFT when compared with those in CFI/CFT after 60 d, which differed from the AI conception rate. Collectively, breeding by ET leads to the avoidance of negative effects of high milk yield and calving on the conception rate, indicating that cows are fertile by ET within 60 d after calving.

A retrospective analysis of conception per embryo transfer in dairy cattle in South Korea

The bovine embryo production industry has seen significant growth over the past two decades, particularly in the production of in vitro produced embryos. This growth, driven by advancements in cryopreservation, in vitro culture mediums, ovum pick-up (OPU) procedures, ultrasonography devices, and embryo transfer (ET) has been notable. Particularly, ET is crucial for disseminating high genetic merit and amplifying foreign breeds by importing frozen embryos. This retrospective study aimed to assess factors affecting conception per embryo transfer (CPET) in Holstein-Friesian cattle in South Korea from October 2008 to July 2022. We evaluated type of embryo breed, type of embryo production (fresh and frozen; in vitro and in vivo production), recipient conditions including estrus type, corpus luteum quality, parity (nulliparous heifers, primiparous, and multiparous cows), and the daily mean temperature-humidity index (THI) as an index for heat stress. Type of embryo breed and estrus had no significant impact on CPET. However, we observed higher CPET in recipients with good quality corpus luteum, nulliparous heifers, and surrogates receiving fresh in vitro and frozen in vivo embryos. Importantly, CPET was not adversely affected by mild heat stress conditions (up to daily mean THI 76), indicating that using frozen in vivo embryos produced by multiple ovulation embryo transfer and fresh in vitro embryos by OPU-ET can help alleviate the subfertility issues in dairy cattle caused by global warming in Korea.

Customized voluntary waiting period before first insemination in primiparous dairy cows. Effect on milk production, fertility and health

Customized voluntary waiting period (VWP) before first insemination was tested in 18 commercial dairy herds in Sweden, to assess milk production, fertility and health in primiparous cows expected to be suited for extended VWP. Cow selection for extended VWP was based on 3 criteria in early lactation: 1) the 10% of cows with highest genomic persistency index, 2) cows with a difficult calving or disease during the first month of lactation, and 3) cows with higher yield during d 4-33 after calving than the herd average for primiparous cows. Cows meeting at least one of these criteria were randomly assigned to either the ExtExt treatment (extended VWP of at least 175 d, n = 174; calving interval (CInt) = 16.3 mo) or the ExtConv treatment (conventional VWP of maximum 100 d n = 173; CInt = 12.4 mo). Cows not meeting any of the criteria were assigned to the ConvConv treatment (conventional VWP, n = 183; CInt = 12.0 mo). There were no differences in milk yield per day in the CInt between treatments, although 305-d and whole-lactation (WL) milk yields were higher for ExtExt cows (10,371 and 13,803 kg) than ExtConv cows (9,812 and 10,257 kg). Milk yield at the last test milking before dry-off was lower in ExtExt compared with ExtConv cows (24.9 vs 28.3), however the results showed no difference in dry period length between the treatments. Regarding reproductive performance, the ExtExt cows had higher first service conception rate (FSCR; 60% vs. 45%) and lower number of inseminations per conception (NINS; 1.67 vs. 2.19), compared with the ExtConv cows. As expected, ConvConv cows had the lowest milk yield in 305-d, in WL, and per day in the CInt, however, FSCR and NINS did not differ between ConvConv cows and cows in the other 2 VWP treatments. Disease incidence was higher for cows in the ExtConv compared with the ConvConv treatment, but there was no difference between ExtExt and the 2 other VWP treatments. Further, no difference in proportion of cows with good udder health or culling rate was detected between any of the treatments, though due to low prevalence the study lacked power to draw major conclusions on these results. Thus prolonging VWP for suitable primiparous cows can produce benefits such as improved fertility in the form of higher FSCR and lower NINS, as well as lower dry-off yield, without compromising milk yield or prolonging dry period length.

Association of genomic prediction for twin pregnancies with the incidence of double ovulation in primiparous dairy cows.

Twin pregnancies compromise the health and well-being of dairy cattle. A recent genomic prediction model for twin pregnancies has been developed based on twin calving or abortion. However, the incidence of double ovulation is significantly higher than that of twin births. This study aimed to evaluate whether genomic prediction values for twin pregnancies are associated with the incidence of double ovulation in primiparous dairy cows. Factors influencing the double ovulation rate were analysed using binary logistic regression on 676 cows: 475 (70.3%) inseminated at spontaneous estrus and 201 following one of two different estrus synchronization protocols for fixed-time artificial insemination (FTAI). The odds ratio for double ovulations was 0.92 (p = .002) per unit increase in prediction value and 2 (p = .01) for cows subjected to an FTAI protocol. Our findings suggest that genomic prediction values for twin pregnancies can effectively identify the risk of double ovulation at the herd level.

Predicting subacute ruminal acidosis from milk mid-infrared estimated fatty acids and machine learning on Canadian commercial dairy herds

Our objective was to validate the possibility of detecting SARA from milk Fourier transform mid-infrared spectroscopy estimated fatty acids (FA) and machine learning. Subacute ruminal acidosis is a common condition in modern commercial dairy herds for which the diagnostic remains challenging due to its symptoms often being subtle, nonexclusive, and not immediately apparent. This observational study aimed at evaluating the possibility of predicting SARA by developing machine learning models to be applied to farm data and to provide an estimated portrait of SARA prevalence in commercial dairy herds. A first data set composed of 488 milk samples of 67 cows (initial DIM = 8.5 ± 6.18; mean ± SD) from 7 commercial dairy farms and their corresponding SARA classification (SARA+ if rumen pH <6.0 for 300 min, else SARA-) was used for the development of machine learning models. Three sets of predictive variables: i) milk major components (MMC), ii) milk FA (MFA), and iii) MMC combined with MFA (MMCFA) were submitted to 3 different algorithms, namely Elastic net (EN), Extreme gradient boosting (XGB), and Partial least squares (PLS), and evaluated using 3 different scenarios of cross-validation. Accuracy, sensitivity, and specificity of the resulting 27 models were analyzed using a linear mixed model. Model performance was not significantly affected by the choice of algorithm. Model performance was improved by including fatty acids estimations (MFA and MMCFA as opposed to MMC alone). Based on these results, one model was selected (algorithm: EN; predictive variables: MMCFA; 60.4, 65.4, and 55.3% of accuracy, sensitivity, and specificity, respectively) and applied to a large data set comprising the first test-day record (milk major components and FA within the first 70 DIM of 211,972 Holstein cows (219,503 samples) collected from 3001 commercial dairy herds. Based on this analysis, the within-herd SARA prevalence of commercial farms was estimated at 6.6 ± 5.29% ranging from 0 to 38.3%. A subsequent linear mixed model was built to investigate the herd-level factors associated to higher within-herd SARA prevalence. Milking system, proportion of primiparous cows, herd size and seasons were all herd-level factors affecting SARA prevalence. Furthermore, milk production was positively, and milk fat yield negatively associated with SARA prevalence. Due to their moderate levels of accuracy, the SARA prediction models developed in our study, using data from continuous pH measurements on commercial farms, are not suitable for diagnostic purpose. However, these models can provide valuable information at the herd level.

SKŁAD MLEKA KRÓW W ZALEŻNOŚCI OD WIEKU, FAZY LAKTACJI I PASZY GENETYCZNIE MODYFIKOWANEJ

The aim of the presented study was to analyze changes in milk composition depending on presence of genetically modified (GM) components in feed and according to cows’ age and lactation phase. The research was carried out with Polish Holstein-Friesian black and white cows (n = 50) housed in tie stall system at one farm. The genetically modified feed was a supplementary feed mixture. Data reports from milking trials with milk chemical composition, number of somatic cells and urea content were collected. The collected data concerned groups: primiparous (P) cows and multiparous (M) cows during 2nd and 3rd lactation. In each age group, two subgroups were distinguished: cows from 1st to 4th month of lactation (I) and cows from 5th to 8th month of lactation (II). The above subgroups were divided according to feed with GM components (G) and feed with non-GM components (N). It was found that use of feed with the addition of GM plants contributes to lowering the level of casein and an increase of lactose in milk. Presence of GM components in feed did not affect the level of fat, total protein, fat to protein content, urea levels, somatic cell counts in milk and cow yield. It can be concluded that the withdrawal of feed additives based on GM components does not adversely affect the technological quality of milk.

Treatment alternatives to induce follicular wave emergence for timed-AI in lactating dairy Cows

Two experiments evaluated the effect of different hormonal treatments to synchronize follicle wave emergence on follicle dynamics and pregnancies per AI (P/AI) in estradiol (E2)/progesterone (P4) timed-AI (TAI) protocols in lactating dairy cows. In Experiment 1, lactating, primiparous Holstein cows (n = 36) received a P4 releasing device (Day 0) and were allocated at random to one of the following three treatment groups: Group EB received 2 mg E2 benzoate (EB) intramuscularly (i.m.), Group EB + GnRH received 2 mg EB+20 μg buserelin (GnRH) i.m., or Group EB + P4 received 2 mg EB + 100 mg of injectable P4 (iP4) in oil i.m. All cows received 0.150 mg D-Cloprostenol on Days 7 and 8 followed by P4 device removal, 400 IU eCG and 1 mg ECP on Day 8. Daily ultrasound examinations revealed that although the interval from P4 device removal to ovulation was not affected by treatment, cows that received EB + GnRH had an earlier (P < 0.05) emergence of the new follicular wave (Day 2.6 ± 0.2) than the other two treatment groups (Days 3.5 ± 0.3 and 6.1 ± 0.3, for EB and EB + P4, respectively). In Experiment 2, 808 lactating cows were assigned randomly to the three treatments evaluated in Experiment 1, and all the cows were TAI to determine P/AI. Cows in the EB + GnRH group had greater P/AI (57.4 %, P < 0.01) than those in the EB (44.6 %) or EB + P4 (45.7 %) groups. In conclusion, the administration of GnRH, but not iP4, on the day of insertion of a P4 device improves P/AI in lactating dairy cows synchronized for TAI with an estradiol/P4-based protocol.

Influence of the season on the main components of cow milk in Ukraine

The quality of dairy products depends on the safety and quality of raw materials, therefore, the analysis of physicochemical and sanitary indicators of raw cow milk is of great importance. The composition of bulk milk of three technological groups of cows: early lactation (5–60 days in milk), primiparous cows and all other cows starting from the second lactation was studied according to seasons. Regardless of the group of animals, the fat content in bulk milk was significantly lower in summer than in other seasons of the year, and the highest in winter. In each group of animals, the lowest somatic cell count was observed in the fall, while the highest indicator of the study of bulk milk of cows in early lactation and primiparous was determined in the winter, and in the spring of cows from the second lactation. The lowest milk urea content in all groups of animals was noted in summer. The lowest protein level was observed in autumn (3.27 ± 0.11%), and the highest in winter (3.39 ± 0.11%) in the bulk milk of cows in early lactation. The ratio of fat to protein in summer 1.12 ± 0.03 was significantly lower compared to other seasons of the year. The highest level of somatic cells was recorded in this group in winter (290 ± 82 * 103 cells/mL), which was twice as much as in autumn (141 ± 54 * 103 cells/mL), and by 56.8% more than in summer (185 ± 39 * 103 cells/mL). The milk urea content in the summer was 194.0 ± 17.6 mg/kg, which is significantly lower than the indicators in other seasons of the year in the group of early lactation. In the summer period, the lowest protein content (3.23 ± 0.06%) in the bulk milk of primiparous cows was observed compared to other seasons of the year. The winter was characterized by the highest level of somatic cell count in milk (221 ± 49 * 103 cells/mL), which was almost twice as high as the autumn period (116 ± 31 * 103 cells/mL). The highest urea content in the milk of primiparous cows was found in autumn (228.6 ± 21.9 mg/kg), which exceeded the summer figure by 14.5%. The lowest protein content (3.29 ± 0.06%) and the highest in winter (3.44 ± 0.09%) was observed in the bulk milk of cows of the second lactation and older. The somatic cell count in milk in autumn (160 ± 69 * 103 cells/mL) was lower than the winter and spring indicators by 37.5% and 49.3%, respectively. The milk urea content in the summer (198 ± 22 mg/kg) was significantly lower than the autumn and winter indicators. In further studies, to improve the sanitary quality of milk, it is planned to use different hygienic means for processing the udder of cows depending on the season.

Association between body condition profiles, milk production and reproduction performance in Holstein and Normande cows

Body-condition dynamics are known to affect the different steps of reproduction in cattle (cyclicity, estrus expression, fertilization, embryo development). This has led to a widespread idea that there is an ideal-target optimal body condition, but no clear profile has yet been identified. Here we investigated the relationships between body condition score (BCS) profiles and reproductive performance in dairy cows. Data were from Holstein or Normande herds in 6 French experimental farms. In the Holstein breed, we discriminated 4 BCS profiles based on combining BCS at calving (Low: around 2.6 points, or High: around 3.3 points) with BCS loss after calving (Moderate (M): ≤ 1.0 points, or Severe (S): > 1.0 points). The Low-M profile mostly included multiparous cows with higher milk yield and lower reproductive performance than cows in the 3 other profiles. Low-M cows that experienced abnormal ovarian activity had lower reproductive performance than their profile-mates. Moreover, 67% of Low-M cows kept the same profile at the following lactation. The High-S profile mostly included primiparous cows with lower milk yield and higher reproductive performance than cows in other profiles. In High-S cows, higher milk yields correlated to higher risk of failure to calf on first insemination. Moreover, 38% of High-S cows kept the same profile at the following lactation, and none changed to Low-M. The other 2 BCS profiles (Low-S and High-M) were intermediate in terms of milk yield and reproductive performance. In Normande, we discriminated 3 BCS profiles based on combining BCS at calving (Low: around 2.6 points, or High: around 3.5 points) with BCS loss after calving (Flat (F): flat with no loss, Moderate (M): around 0.5 points, or Severe (S): around 1.0 point). The Low-M and High-S profiles included cows with similar performance, even though High-S-profile cows showed better but not significantly different milk yield and reproduction performance. The High-F profile included cows that were more likely to experience abnormal ovarian activity and fail at first insemination than cows in other profiles. More than 50% of Normande cows with 2 successive lactations kept in the same BCS profile at the next lactation. Even though a low BCS at calving combined with severe BCS loss (more than 1 point) after calving was found to increase reproductive failure, there was no evidence of an optimal BCS profile for reproduction in dairy cows, and reproductive success or failure is multifactorial.

Change in the incidence of stillbirth in Japanese Black cattle during the animal movement restrictions and suspended insemination.

We aimed to characterize the change in the incidence of stillbirth (IS) in Japanese Black cattle during and after animal movement restrictions and suspended insemination because of a foot-and-mouth disease (FMD) outbreak in Miyazaki Prefecture in 2010. Calving data from 2006 to 2018 were collected from approximately 900 farms. Post-FMD period was divided into three based on the median IS per month (1.80%): period 1 (May 2011 to February 2013), period 2 (March 2013 to August 2015), and period 3 (September 2015 to December 2018). The ISs were similar during the Pre-FMD period and Post-FMD period 1, then substantially decreased during Post-FMD period 2 (p < .05), before returning to the value before the FMD outbreak period during Post-FMD period 3. Compared with the Pre-FMD period, Post-FMD period 1 was associated with a higher proportion of calvings by primiparous cows and Post-FMD period 2 was associated with a smaller number of calvings per month (p < .05). There were high ISs in primiparous cows during the Pre-FMD period, Post-FMD period 1, and Post-FMD period 3 (p < .05), but not during Post-FMD period 2. In summary, after the animal movement restrictions and suspended insemination introduced because of the FMD outbreak, the IS temporarily decreased and consequently returned to the pre-FMD level.

Increased dietary methionine, lysine and histidine supply modulated the heat stress-induced metabolic remodeling of dairy cows

Increasing dietary Met, Lys, and His supply without increasing the dietary protein content was reported to partially alleviate the productive and physiological impact of heat stress. Nevertheless, the metabolic pathways involved are yet to be identified. Thus, we aimed to explore the metabolic pathways associated with these positive effects and develop new metabolomics-based hypotheses. Twelve lactating Holstein cows (primiparous, n = 6; multiparous, n = 6; 42.2 ± 10.6 kg/d milk yield; 83 ± 28 days in milk) were enrolled in two 3×3 replicated Latin squares consisting of 14-day treatment periods: heat stress [HS; max. Temperature Humidity Index (THI) 84, 16.8% crude protein (CP), 1,741 g/d metabolizable protein (MP), 108 Lys, 33 Met, and 37 His (g/d)], pair feeding in thermo-neutrality (TN; max. THI 64, same diet as HS), and HS with increased Lys, Met and His supply [HS+AA; max. THI 84; 17.0% CP, 1,730 g/d MP, 179 Lys, 58 Met, and 45 His (g/d)]. Blood plasma and milk were sampled on day 14 for metabolomics profiling. Several amino acids (AA) and derivatives differed between the treatments. Plasma and milk Met, Val, Trp and α-amino adipic acid concentrations were highest in HS+AA (false discovery rate-P (FDR) &amp;lt; 0.05). Moreover, only plasma Lys and milk His were highest in HS+AA (FDR &amp;lt; 0.05). Some phosphatidylcholines (PC) and diglycerides had lower concentrations in HS than TN (FDR &amp;lt; 0.05), while HS+AA had similar concentrations as TN. The pathway enrichment analysis revealed that the AA-related pathways were more significantly affected in multiparous than in primiparous cows. Our results suggest that increased supply of Met stimulated PC synthesis in HS+AA to similar concentrations as in TN. Increased Lys supply likely elevated the oxidation rate of Lys and downregulated the catabolism of other essential AA (EAA) such as Val and Trp, stimulating milk protein synthesis. No clear associations were found related to His availability. In conclusion, partial amelioration of productive and physiological effects of heat stress associated with increased dietary Met and Lys supply were likely explained by stimulated PC synthesis and increased plasma and milk concentrations of other EEA.

Plant-animal relationship, metabolic and behavioral adaptations, and their association with production levels in primiparous cows in response to changes in herbage allowance in Basaltic native grasslands

Based on a two-level of herbage allowance (OF) with seasonal variations experiment, two experiments were conducted in spring-calving primiparous cows on basalt campos. Experiment 1 (Exp1) assessed high OF (AOF) and low OF (BOF) in cows undergoing temporary weaning and flushing (DTF) at the beginning of the breeding season, while Experiment 2 (Exp2) investigated the interaction between AOF and BOF levels pre and postpartum without DTF. Herbage quantity and height were generally below recommended values and they were higher in AOF during autumn and summer compared to BOF, explained by a lower stocking rate (~30%). In Exp1, AOF increased concentrations of IGF-I and insulin, and BCS in autumn, explained by higher herbage intake. These changes had a positive impact on IGF-I concentrations during winter and after the start of DTF in AOF compared to BOF, attributed to a carryover effect or metabolic memory, explaining the higher probability of ovulation and pregnancy. After DTF, AOF cows exhibited greater behavioral plasticity: a lower proportion of daytime spent grazing and more on rumination and walking, staying closer to their calves compared to BOF. The calves’ weight after 120 days was higher in AOF compared to BOF, associated with increased calves’ herbage intake and cow-calf proximity. In Exp2, BCS levels would have been sufficient to mitigate the negative energy balance in winter, explaining the absence of a prepartum OF effect. Postpartum AOF increased herbage intake compared to BOF and recorded higher concentrations of IGF-I, milk production, calf weight from 90 days, and the proportion of cows that ovulated. The OF affected the nutritional plane at different times between experiments; however, AOF in both experiments increased meat production per cow, biological efficiency and production per area associated with higher herbage intake, and metabolic and behavioral plasticity. The results contribute to the design of more productive, resilient and environmentally friendly systems.

Fecal egg counts and individual milk production in temperate pastoral dairy systems of Australia

Anthelmintic use in lactating dairy cattle, has been shown to result in a milk production response in some previous studies. If individual animals within a herd could be identified that would most benefit from anthelmintic treatment, this may reduce anthelmintic resistance. Australian dairy systems are predominantly pasture-based, allowing sustained exposure and immune stimulation of cattle to gastrointestinal nematodes. We assessed the relationship between milk production and early lactation fecal egg counts (FEC) to determine whether cows with higher FEC produced less milk. Ten pasture-based dairy farms in south-west Victoria, Australia, entered an observational study. Individual FECs at a minimum detectable count of 2.5 eggs per gram of feces (epg) were recorded for recently calved primiparous and multiparous cohorts on each farm. All animals were calved ≤30 d at sampling. Body condition scores were assessed at sampling and milk production data was collected from daily milk meters and herd tests to give first 100-d milk production. When separated by primiparous or multiparous status, no difference in the milk production between cows with FEC = 0 and FEC ≥2.5 epg was identified. Between farm variation was large for FEC and milk production. Fecal egg count at a minimum detectable count of 2.5 epg detected parasitism in primiparous cows post calving but the presence and magnitude of parasitism measurable by FEC was not related to milk production in pasture based Australian dairy systems. In multiparous cows, the rate detection of worm eggs at this analytical sensitivity was lower and the significance of a positive FEC at this analytical sensitivity requires further assessment to ascertain the effect on milk production. Based on our study, it seems unlikely that individual FEC results would be useful as a basis to select individual cows in southwest Victorian dairy herds for anthelmintic treatment.

Effect of oxytocin use during colostrum harvest and the association of cow characteristics with colostrum yield and immunoglobulin G concentration in Holstein dairy cows

Our objectives were to determine the effect of oxytocin use during colostrum harvest on colostrum yield and IgG concentration in Holstein dairy cows on a commercial dairy in New York and to describe associations of cow characteristics with these outcomes. Animals were enrolled between July and October 2023 using a randomized block design, with day of enrollment as the unit of randomization. A median (range) of 10 (3-19) cows were enrolled per day. Treatments were (1) 40 IU oxytocin (OXY40), (2) 20 IU oxytocin (OXY20), and (3) an untreated control group (CNTR). Oxytocin was administered i.m. ∼45 s before unit attachment in a rotary parlor. Colostrum weight was measured using the colostrum bucket-embedded scale or a platform scale when the yield was less than the smallest bucket scale. The concentration of IgG ([IgG]) in colostrum was determined using radial immunodiffusion and used to calculate total IgG, and DM (%) was determined by oven drying. Individual cow characteristics such as parity, calf sex, weight, dystocia score, stillbirth, and milk production in wk 4 of lactation; additionally, for multiparous cows, dry period length and previous lactation dry-off linear SCS were collected. Data were analyzed separately for primiparous and multiparous cows using backward stepwise elimination. To produce final mixed effects ANOVA models, primiparous cows (n = 201) were randomized to 35.8% (n = 72) OXY40, 32.8% (n = 66) OXY20, and 31.3% (n = 63) CNTR. Multiparous groups (n = 435) were randomized to 34.7% (n = 151) OXY40, 29.7% (n = 129) OXY20, and 35.6% (n = 155) CNTR. The median (range) colostrum yield was 6.0 (0-20.6) kg and [IgG] was 98.5 (0.1-293.6) g/L in the study population. In primiparous cows, OXY40 had a higher colostrum yield (LSM [95% CI]) of 5.4 (4.9-5.9) kg compared with both OXY20 (4.1 [3.5-4.7] kg) and CNTR (3.8 [3.3-4.3] kg). In multiparous cows, OXY40, OXY20, and CNTR did not differ in colostrum yield (5.9 [5.3-6.5], 5.7 [5.1-6.3], and 5.4 [4.8-6.0] kg, respectively), but colostrum yield was greater in parity 2 compared with all other parities, cows giving birth to male calves, cows with the highest milk production at wk 4 of lactation, and cows with a dry period of >65 d. Oxytocin use did not affect [IgG] in either primiparous or multiparous cows, but [IgG] was highest in cows in parity ≥4 and lowest in cows dry >65 d. In summary, oxytocin use at 40 IU i.m. was associated with a higher colostrum yield in primiparous cows only and no change in [IgG]. Oxytocin use likely addressed disturbed milk ejection and therefore increased colostrum yield in heifers milked for the first time in a rotary parlor. This study confirms cow characteristics associated with colostrum production within a single herd.

Effects of parity and week after calving on the metabolic, redox, and immune status of dairy cows

At the onset of lactation in dairy cows, inflammation and oxidative stress may occur and result in a risk of pathologies and lower milk yield. To propose an innovative management strategy for cows during this period, it is essential to better understand these physiological variations. Our objective was to evaluate the metabolic, redox and immune status of 7 primiparous and 8 multiparous Holstein cows during late gestation and the first months of lactation. Blood samples were collected between 3 weeks before calving until 12 weeks postpartum. Milk samples were also collected, but only at the time points after calving. The metabolic (nonesterified fatty acids (NEFA), BHB, glucose, urea, calcium) and redox (reactive oxygen metabolites (ROM), oxidative stress index (OSI), glutathione peroxidase activity, vitamin E) statuses were analyzed in plasma or erythrocytes. The expression of genes related to antioxidant functions was determined in leukocytes collected from milk. For immune status, plasma cytokine levels and the production of reactive oxygen species (ROS) in classical and regulatory neutrophils were measured in 2 whole blood ex vivo challenges. The data were analyzed using a mixed model that included the fixed effects of parity and week and their interaction. Milk yield, plasma NEFA and BHB in wk 2 and 4 after calving were higher in multiparous cows than in primiparous cows, whereas glucose and calcium tended to be lower. Plasma ROM and OSI levels in wk 8 were higher in multiparous than in primiparous cows. Multiparous cows also displayed higher glutathione peroxidase activity in erythrocytes, and antioxidant transcription factor and superoxide dismutase-1 expression levels in milk leukocytes. Moreover, multiparous cows had higher plasma concentrations of vitamin E but lower plasma levels of cytokines CXCL10, CCL2, IL1Rα and IFNγ. Following ex vivo whole blood stimulation with Escherichia coli, lower IL1α and TNFα levels were measured in multiparous than in primiparous cows. Intracellular ROS production by neutrophils was lower in multiparous than in primiparous cows. These results thus indicated marked physiological changes in wk 8 compared with wk 2 and 4 of lactation. These differences in the physiological status of primiparous and multiparous cows offer interesting perspectives for potential dietary strategies to prevent pathologies which take account of parity and week relative to calving.