Microclimate modeling in naturally ventilated dairy barns during the hot season: Checking the accuracy of forecasts.

Monitoring and predicting the microclimate in naturally ventilated barns (NVB) is important given the adverse effects of high summer temperatures on dairy cows in the context of global climate change. The aim of the work was to verify the accuracy of the microclimate forecast in a NVB using linear regression (LR). Our working hypothesis suggested that multiple periodic measurements of air temperature and relative humidity outside and inside the barns at the same time will allow us to build LR models for predicting the temperature-humidity index (THI). This was done not only for a specific dairy barn based on this indicator outside, but also in other dairy barns with a similar design, located in similar weather conditions. The results of the research indicate that the use of LR had a high accuracy of forecasting (93-96%) the THI in NVB of various designs during the summer heat. At the same time, differences were found between traits (air temperature, relative humidity as well as resulting THI) provided by meteorological weather stations and these data measured simultaneously next to the dairy barns. The proposed LR models can be used to predict THI in NVBs of different designs.

The autumn low milk yield syndrome in Brown Swiss cows in continental climates: hypotheses and facts.

Extensive research has been conducted globally on the impact of heat stress (HS) on animal health and milk production in dairy cows. In this article, we examine the possible reasons for the decrease in milk production in Brown Swiss (BS) cows during the autumn season, known as the autumn low milk yield syndrome (ALMYS). This condition has been extensively studied in high-yielding Holstein Friesian (HF) cattle and has also been observed in BS cows with a daily milk yield of around 30 kg. Our hypothesis is that the drop in milk yield and the increased prevalence of mastitis in autumn, as found in our recent studies, may be a long-term consequence of summer HS. We re-evaluate our previous findings in light of the possible manifestation of an HS-related form of ALMYS in BS cows. As milk yield, mastitis spread, and reproductive function of cows are interrelated and have seasonal dependence, we examine the consistency of our hypothesis with existing data. The significant drop in milk yield in BS cows in autumn (by 2.0-3.2 kg), as well as the threshold of milk yield decrease (temperature-humidity index of 70.7), may point in favour of the manifestation of ALMYS in BS cows, similar to HF cows. Only the percentage effect of seasonal factor (59.4%; p < 0.05) on milk yield of BS cows was significant. HS-related ALMYS provides a robust conceptual framework for diverse sets of productive and animal health data in BS cows, similar to observations in high-yielding HF cattle. However, the limitations associated with the lack of additional data (e.g. immunological indicators) suggest the need for further research to confirm ALMYS in BS breed.

Changes in the Spectrum of Free Fatty Acids in Blood Serum of Dairy Cows during a Prolonged Summer Heat Wave.

This experiment was conducted to study the effect of a prolonged hot period on the fatty acid (FA) composition in blood serum of dairy cows. Eighteen multiparous Holstein cows were randomly assigned to the hyperthermia group (HYP, n = 8) in August (summer season) and the control group (CON, n = 10) in October (autumn season). Blood from animals of the HYP group was collected in one heat wave, which was preceded by a long period of heat stress (HS, temperature-humidity index (THI ≥ 72)). Blood from cows of the CON group was collected under thermal comfort conditions (THI < 68). The spectrum of free fatty acids (FFA) in the blood serum was analyzed by gas chromatography. The concentration of FFA increased, including saturated FAs and monounsaturated FAs, in the blood serum of cows under conditions of prolonged HS. This was associated with the mobilization of FA into the bloodstream from adipose tissue, as a consequence of negative energy balance. An increase in the ratio of n-6/n-3 polyunsaturated FAs may indicate biomembrane dysfunction and adversely affect dairy cows. This study showed that prolonged periods of heat can affect the FA composition of blood. How much this leads to changes in the FA composition of milk and the quality of food products remains to be seen in further research.

Determining the optimal insemination time of bitches / Determinando el momento óptimo de inseminación en perras

Resumen En la actualidad, criar perros requiere una aproximación competente y con base científica. En particular, la elección del momento óptimo de inseminación (tanto natural como artificial) es uno de los factores más importantes para el éxito en el apareamiento o inseminación de perras, y es crucial para problemas de infertilidad. El período de fertilización (tiempo en el cual los ovocitos pueden ser fertilizados) es de 2 a 5 días luego de la ovulación. Por ende, la cópula debería realizarse inmediatamente antes o durante este período. El momento óptimo puede determinarse utilizando varios métodos que estiman el período de fertilidad (cuando la cópula/inseminación tiene máximas chances de concepción). Sin embargo, ninguna de las técnicas diagnósticas es absolutamente confiable, por lo que para un resultado lo más certero posible se recomienda sar varios (dos o tres) estudios. Por ejemplo: contar los días, examen de descarga vulvar y vaginal sumado a frotis y/o vaginoscopía. La cópula control incrementa las chances de concepción, y debe realizarse el día después de la primera cópula. Debe considerarse que el momento de ovulación en la misma perra en distintos celos puede ser diferente. Para perras con problemas de concepción debe usarse el máximo número de métodos con un análisis de intentos pasados fallidos o exitosos. La elección de un método específico implica un aspecto económico, tal como cuando el propietario debe trasladar la perra una larga distancia y necesitan saber la fecha exacta de ovulación.

Abstract Nowadays, breeding dogs requires a competent, science-based approach. In particular, the choice of the optimal insemination time (both natural and artificial) is one of the important factors of successful mating or artificial insemination of bitches and is crucial in the problem of infertility. The period of fertilization (the time when ovicells can be fertilized) is 2-5 days after ovulation. Therefore, mating should be performed immediately before or during this period. The optimal time can be determied using various methods that estimate the period of fertility (when mating/inseminación can lead to conception). However, none of the diagnostic techniques is absolutely reliable, so for the most accurate result, it is recommended to use several (two or three) studies. For example: counting days, assessment of vulvar and vaginal discharge plus smear and/or vaginoscopy. Control mating increases the probability of conception and is usually performed the day after the first mating. It should be considered that the time of ovulation in the same bitch during different heat can be different. For bitches with problems of conception use the maximum number of methods with the analysis of past successful and unsuccessful matings. Choosing a specific method also implies an economic aspect, such as when owners have to carry bitches for a long distance and they need to be sure of the exact date of ovulation.