Automated activity monitoring (AAM) systems are critical in the dairy industry for detecting estrus and optimizing the timing of artificial insemination (AI), thus enhancing pregnancy success rates in cows. This study developed a predictive model to improve pregnancy success by integrating AAM data with cow-specific and environmental factors. Utilizing data from 1,054 cows, this study compared the pregnancy outcomes between two AI timings—8 or 10 h post-AAM alarm. Variables such as age, parity, body condition, locomotion, and vaginal discharge scores, peripartum diseases, the breeding program, the bull used for AI, milk production at the time of AI, and environmental conditions (season, relative humidity, and temperature–humidity index) were considered alongside the AAM data on rumination, activity, and estrus intensity. Six predictive models were assessed to determine their efficacy in predicting pregnancy success: logistic regression, Bagged AdaBoost algorithm, linear discriminant, random forest, support vector machine, and Bagged Classification Tree. Integrating the on-farm data with AAM significantly enhanced the pregnancy prediction accuracy at AI compared to using AAM data alone. The random forest models showed a superior performance, with the highest Kappa statistic and lowest false positive rates. The linear discriminant and logistic regression models demonstrated the best accuracy, minimal false negatives, and the highest area under the curve. These findings suggest that combining on-farm and AAM data can significantly improve reproductive management in the dairy industry.

The aim of this study was to evaluate total weight gain, carcass yield, rib-eye area, marbling, subcutaneous fat thickness, frequencies of mounting, excitement, dominance behaviour and serum testosterone concentration in feedlot-finished non-castrated bulls, surgically castrated bulls, immunocastrated bulls and bulls treated with homeopathy. The study involved 52 calves, Holstein-Zebu, 20±3 months old, in a completely randomised design divided into four treatments of 13 animals: non-castrated, surgically castrated, immunocastrated and non-castrated with homeopathy. Analysis of variance was performed, and the Tukey test was applied (P<0.05). The Pearson correlation coefficient was estimated and principal components analysis was performed. The castrated animals had lower total weight gain and carcass yield than the animals in the remaining treatment groups. The immunocastrated bulls had a greater subcutaneous fat thickness than the non-castrated bulls. The castrated bulls exhibited lower frequencies of mounting, excitement and dominance behaviour than the animals in the remaining treatment groups. Testosterone levels were lower in the castrated animals. Principal components analysis revealed a moderate magnitude and sharpness in the differentiation of the castrated animals. It was concluded that the immunocastrated animals were similar in performance to the non-castrated animals, while the carcass finish characteristics of the immunocastrated animals were similar to the castrated animals. The castrated animals had lower productive performance than the animals in the remaining treatment groups. The homeopathy animals had performance and carcass finish characteristics similar to the non-castrated animals. Homeopathy and immunocastration did not reduce sodomy and dominance behaviours.

Milk composition and blood metabolic profile from holstein cows at different calving orders and lactation stages

The effects of endometritis, pododermatitis and clinical mastitis on the conception rate and calving-conception interval of multiparous and primiparous cows after fixed-time artificial insemination (FTAI) were evaluated. Clinical endometritis was diagnosed by ultrasonography 20-40 days postpartum upon observation of fluid in the uterine lumen. Cows with clinical endometritis were treated intramuscularly with 2 mg/kg ceftiofur hydrochloride over three consecutive days. Forty-five days after delivery, multiparous and primiparous cows with normal uteri according to ultrasonography were selected for the study, filed and inseminated by FTAI. To identify animals with hoof problems and clinical mastitis and to define their respective groups, the cows were observed daily during morning and nightly milking for up to 60 days after FTAI, and animals with hoof lesions were treated. Animals with clinical mastitis were treated with intramammary infusion containing 88 mg cefquinome sulphate every 12 h after milking for four days. The conception rate of multiparous cows with clinical endometritis at 30 and 60 days after FTAI was negatively affected compared with that of healthy cows with pododermatitis. However, clinical endometritis did not influence the primiparous category, whereas pododermatitis and clinical mastitis did not influence the conception rate of any category at 30 and 60 days after FTAI. Differences were not observed between primiparous or multiparous cows in the calving-conception interval. Key words: Lactation, pregnancy, health, fertility.

The present study evaluated the effect of administering buserelin acetate (GnRH) at the time of fixed-time artificial insemination (FTAI), along with the effect of oral administration of melengestrol acetate (MGA) after FTAI on conception rates in non-suckling Nelore cattle. In Experiment I, the effect of GnRH application at the time of FTAI was evaluated, as was administration of MGA from the 13th through the 18th day following FTAI (D24 to D29 after the initiation of the FTAI protocol). Experiment I was performed in 215 non-suckling cattle of the Nelore breed, divided into four experimental groups: Control group: 56 cows subjected to FTAI without GnRH injection; GnRH group: 51 cows subjected to GnRH at the time of FTAI; MGA Group: 57 cows subjected to FTAI without the application of GnRH with mineral supplementation and the addition of 2.28 g of MGA® Premix per cow per day from D24 to D29 after the initiation of the FTAI protocol; MGA and GnRH group: 51 cows subjected to GnRH injection at the time of FTAI, with mineral supplementation and the addition of 2.28 g of MGA® Premix per cow per day from D24 to D29 after the initiation of the FTAI protocol. In Experiment II, the effect of providing MGA five to ten days after FTAI was evaluated in 196 non-suckling pluriparous Nelore cows, divided into two groups: Control group: 104 cows subjected to FTAI, not supplemented with MGA; treated group: 92 cows supplemented with the addition of 2.28 g of MGA® Premix per cow per day from D15 to D20 after the initiation of the FTAI protocol. Diagnosis of gestation was carried out 45 days after FTAI. Both experiments were conducted using a completely randomised design and analysed via the SAS MIXED procedure. In Experiment I, the control group displayed a lower conception rate (32.1%) compared with the groups administered GnRH, MGA, and both MGA and GnRH, which were respectively provided with MGA after FTAI (45.6%), GnRH at the time of FTAI (50.9%), and the combination of the two treatments (50.9%) (P<0.05). In Experiment II, the control group displayed a higher conception rate (40.38%) compared with the group receiving MGA post-FTAI (18.48%) (P<0.05). It was concluded that the injection of buserelin acetate (GnRH) at the time of FTAI and the oral administration of MGA® Premix from the 13th to the 18th day after FTAI increased the conception rates in non-suckling Nelore cattle. However, when MGA® Premix was administered orally from the fifth to tenth day post-FTAI, conception rates in non-suckling Nelore cattle were reduced.

This study aimed to evaluate the influence of reusing progesterone intravaginal implants using a fixed-time artificial insemination (FTAI) protocol on the conception rates of 593 primiparous and multiparous lactating cows during two different seasons. The cows were divided into two categories: multiparous and primiparous. The experiment was conducted during seasons with high and mild temperatures. To compare the conception rates during both seasons, the animals were randomly divided into three groups according to use progesterone implant (1st use, 2nd use and 3rd use) on the first day of the synchronization protocol for FTAI within each category. A pregnancy diagnosis was performed at 30 days following FTAI. The temperature and humidity index was higher (P<0.01) during the season with higher temperatures (74.4 ± 0.26) than during the season with mild temperatures (67.5 ± 0.34). The different categories (multiparous and primiparous) did not influence the conception rate in terms of the seasonal temperatures or the reuse of progesterone implants. Nevertheless, a 3rd use implant administered during the season with high temperatures was 1.98 times less likely to result in a pregnancy compared with a 1st use implant (P=0.01) and 2.83 less likely to result in a pregnancy than the other implants used during the season with mild temperatures (P=0.005). The results indicate that during the season with mild temperatures, the conception rates at 30 days are not influenced by reusing the P4 implant in any of the categories analyzed. However, during the season with high temperatures, the reuse of the P4 implant can influence the conception rates of dairy cows. Key words: Heat stress, Holstein cows, pregnancy.