Resumen El objetivo fue determinar las características ultrasonográfica B mode y Doppler del folículo dominante y cuerpo lúteo en vacas Criollas sometidas a un protocolo de sincronización de celo. El estudio fue realizado en la Estación Experimental Agraria ILLPA durante los meses de mayo a julio utilizando 15 vacas de raza Criolla con condición corporal regular y alimentadas con pasto natural, el protocolo consistió en colocar benzoato de estradiol y dispositivo intravaginal el primer día, posteriormente el día 7 se retiró el dispositivo y se aplicó un análogo de Prostaglandina F2α, el día 8 se aplicó nuevamente benzoato de estradiol y el día 9 se realizó la inseminación artificial con semen de un solo reproductor de raza Fleckvieh, la evaluación ultrasonográfica fue realizada los días 7 y 9 (iniciado la sincronización) para determinar el diámetro del folículo dominante, tasa de crecimiento y diámetro de cuerno uterino, la evaluación del cuerpo lúteo fue realizada el día 19 determinando el diámetro, volumen y área vascular luteal (%), todos los análisis fueron realizados con el programa Jamovi 1.6.23.0. Los resultados del folículo dominante el día 7 fue de 8.69 mm y día 9 de 10.7 mm con una tasa de crecimiento de 1.14 mm/día, el diámetro del cuerno uterino derecho fue 11.85 mm (día 7) mismo que aumento a 15.32 mm (día 9) mientras el cuerno izquierdo aumento de 12.72 a 16.27 mm, las características del cuerpo lúteo fueron diámetro 7.96 mm, volumen 0.23 mm3 y área vascular luteal fue de 20.96 %, finalmente, la tasa de preñez obtenida fue 6 vacas de 15 inseminadas que representa el 40 %. En conclusión, los diámetros y volumen del folículo dominante y cuerpo lúteo son inferiores a lo reportado en otras razas en las mismas condiciones ambientales, el área vascular luteal fue de 20.96 % proporción de irrigación sanguínea del CL en vacas Criollas finalmente la tasa de preñez fue del 40 %. Sin embargo, es necesario indicar que son los primeros reportes de características Doppler en vacas Criollas.

Abstract The objective was to determine the ultrasonographic B mode and Doppler characteristics of the dominant follicle and corpus luteum in Criollo cows subjected to an oestrus synchronization protocol. The study was conducted at the Agricultural Experimental Station ILLPA during the months of May to July using 15 Criollo cows with regular body condition and fed with natural pasture, the protocol consisted of placing estradiol benzoate and intravaginal device on the first day, then on day 7 the device was removed and an analogue of Prostaglandin F2α was applied, On day 8 estradiol benzoate was applied again and on day 9 artificial insemination was performed with semen from a single Fleckvieh sire, ultrasonographic evaluation was performed on days 7 and 9 (synchronization started) to determine the diameter of the dominant follicle, growth rate and diameter of the uterine horn, the evaluation of the corpus luteum was performed on day 19 determining the diameter, volume and luteal vascular area (%), all the analyses were performed with the Jamovi 1 Programme. 6.23.0. The results of the dominant follicle on day 7 was 8.69 mm and day 9 was 10.7 mm with a growth rate of 1.14 mm/day, the diameter of the right uterine horn was 11.85 mm (day 7) which increased to 15.32 mm (day 9) while the left horn increased from 12.72 to 16.27 mm. 72 to 16.27 mm, the characteristics of the corpus luteum were 7.96 mm diameter, volume 0.23 mm3 and luteal vascular area was 20.96 %, finally, the pregnancy rate obtained was 6 cows out of 15 inseminated which represents 40 %. In conclusion, the diameters and volume of the dominant follicle and corpus luteum are lower than those reported in other breeds in the same environmental conditions, the luteal vascular area was 20.96 %, the proportion of blood irrigation of the CL in Criollo cows and finally the pregnancy rate was 40 %. However, it is necessary to point out that these are the first reports of Doppler characteristics in Criollo cows.

ABSTRACT This study was carried out to determine the effect of the entomopathogenic fungus Beauveria bassiana on the control of ticks in cattle. In total, 20 Fleckvieh female cattle were distributed in five treatments: T1 = control group, T2 = excipients (water + 0.6 ml of surfactant), T3 = 1.2x107 conidia (80 g of fungus + 0.2 ml surfactant), T4 = 2.4 x107 conidia (160 g of fungus + 0.4 ml of surfactant), T5 = 3.6x107 conidia (240 g of fungus + 0.6 ml of surfactant). The fungus was washed with water and surfactant to detach them from the substrate and then applied to the cattle by thick-drop spraying. The tick count was performed in six areas (neck table, groin, armpit) on days 0 (before treatment), 1, 2, 3, 5, 7, 9, 11 and 14. The significant decrease in the number of ticks were observed from day 7 on T3, T4, T5. The decrease in ticks on day 14 was 99% in T5, while in T3 and T4 it was 91 and 82%, respectively.

RESUMEN La investigación fue realizada para determinar el efecto del hongo entomopatógeno Beauveria bassiana en el control de garrapatas en ganado bovino. Se trabajó con 20 bovinos hembra de raza Fleckvieh distribuidos en cinco tratamientos: T1= grupo control, T2= excipientes (agua + 0.6 ml de surfactante), T3= 1.2x107 conidias (80 g de hongo + 0.2 ml surfactante), T4= 2.4x107 conidias (160 g de hongo + 0.4 ml de surfactante), T5 = 3.6x107 conidias (240 g de hongo + 0.6 ml de surfactante). El hongo fue lavado con agua y surfactante, con el fin de desprenderlas del sustrato para luego ser aplicado a los bovinos por medio de aspersión por gota gruesa. El conteo de garrapatas se realizó en seis zonas (tabla del cuello, entrepierna, axila) los días 0 (antes del tratamiento), 1, 2, 3, 5, 7, 9, 11 y 14. La disminución significativa en el número de garrapatas se observó a partir del día 7 en T3, T4, T5. La disminución de garrapatas en el día 14 fue de 99% en T5, mientras que en T3 y T4 fue de 91 y 82%, respectivamente.

Certain fatty acids (FAs), such as omega-3 and conjugated linoleic acid (CLA) are considered essential FAs with beneficial health effects for humans. Milk is considered a relatively inexpensive and readily available source of these FAs and is part of a recommended healthy daily diet. The aim of the study was to determine the effect of diet changes on the FA composition of Jersey (J) and Fleckvieh x Jersey (FxJ) milk. Cows were alternately put on kikuyu-ryegrass pasture, followed by a feedlot system, then returned to kikuyu-ryegrass pasture for four weeks each. The same concentrate mixture was fed to cows regardless of feeding system. The feedlot system consisted of a partial total mixed ration (pTMR). Milk samples were collected two and four weeks after diet changes and stored at -20 °C until laboratory analysis by gas chromatography. The FA concentration of milk was not affected by breed, although it was affected significantly by diet changes. Most notably, the total omega-3 and -6 FAs decreased when cows were fed pTMR while increasing when the diet was changed back to pasture feeding. The CLA content of milk was similarly affected. That is, concentrations decreased significantly when the cows were on the pTMR diet and increased when cows were put back on the pasture-based diet. The results suggested that the health benefits of milk fat are affected negatively when cows are fed pTMR compared with being fed in a pasture-based system. The health benefits of milk are reduced owing to decreased levels of the CLA content of milk fat. Therefore, feeding additional hay in a pasture-based production system should be reconsidered when aiming to produce milk that provides health beneficial qualities.

Crossbreeding is regarded as a faster way than using pure dairy breeds to improve the reproductive performance of dairy cows, which is pivotal to farm income. The reproductive performances of Jersey and Fleckvieh x Jersey (F x J) heifers and cows were compared in a pasture-based production system. Heifers were inseminated when showing signs of heat from 13 months old and cows from 40 days post calving. Using insemination records and pregnancy check results, fertility traits were derived and compared between breeds, using analysis of variance for continuous records. Age at first insemination and conception age for heifers did not differ between the two breeds, resulting in a similar age at first calving. For cows, the mean (± SE) interval from calving to first insemination was shorter for F x J cows, being 76.7 ± 2.2 days compared with 82.4 ± 2.5 days for Jersey cows. A larger proportion of F x J cows were inseminated within 80 days post calving, compared with the Jersey cows (0.70 and 0.54, respectively). Furthermore, the proportion of cows confirmed pregnant by 100 days in milk was higher for F x J cows in comparison with Jersey cows, being 0.79 and 0.66, respectively. Although the absolute number of days between calving and conception (days open) was slightly less for F x J cows in comparison with Jersey cows (104.8 ± 6.8 and 114.8 ± 8.1 days, respectively), the difference was not significant. These results indicate the potential of improving reproductive performance of Jersey cows through crossbreeding with the dual-purpose Fleckvieh.

A number of fatty acids (FAs), such as omega-3, omega-6 and conjugated linoleic acid (CLA), which are present in the milk from dairy cows are considered essential FAs and beneficial nutrients for humans. The aim of the study was to compare the milk FA content, particularly the CLA, omega-3 and omega-6 FA content of the milk fat of Jersey and Fleckvieh x Jersey (F x J) cows in a pasture-based feeding system. All cows were fed the same diet consisting of kikuyu-ryegrass pasture in a rotational grazing system supplemented with a standard commercial concentrate mixture at 7 kg per cow per day. Five milk samples were collected every five weeks from 10 days after calving, that is, days in milk (DIM) up to 175 DIM. In addition, two samples were collected every five weeks from 240 DIM to the end of the lactation period. Sampling was done at the evening and following morning's milking session and pooled for each cow. Samples were kept frozen at -20 °C until laboratory analysis by gas chromatography. Thirty six FAs were detected and concentration levels determined. Higher levels of total CLA (0.74 ± 0.02 vs. 0.63 ± 0.02 g FA/100 g fat), linoleic acid (1.51 ± 0.03 vs. 1.36 ± 0.04 g FA/100 g fat) and total omega-6 FAs (1.74 ± 0.04 vs. 1.54 ± 0.05 g FA/100 g fat) were recorded in the milk fat of F x J cows in comparison with Jersey cows, respectively. Increases in total CLA and the c9,t11 CLA isomers in the milk of Jersey and F x J cows followed the same trend, showing an increase from the beginning to the end of the lactation period. Similarly, the CLA content of the milk fat showed an increase with lactation stage for both breeds.