NASA POWER satellite meteorological system is a good tool for obtaining estimates of the temperature-humidity index under Brazilian conditions compared to INMET weather stations data.

Heat stress negatively affects livestock, with undesirable effects on animals' production and reproduction. Temperature and humidity index (THI) is a climatic variable used worldwide to study the effect of heat stress on farm animals. Temperature and humidity data can be obtained in Brazil through the National Institute of Meteorology (INMET), but complete data may not be available due to temporary failures on weather stations. An alternative to obtaining meteorological data is the National Aeronautics and Space Administration Prediction of Worldwide Energy Resources (NASA POWER) satellite-based weather system. We aimed to compare THI estimates obtained from INMET weather stations and NASA POWER meteorological information sources using Pearson correlation and linear regression. After quality check, data from 489 INMET weather stations were used. The hourly, average daily and maximum daily THI were evaluated. We found greater correlations and better regression evaluation metrics when average daily THI values were considered, followed by maximum daily THI, and hourly THI. NASA POWER satellite-based weather system is a suitable tool for obtaining the average and maximum THI values using information collected from Brazil, showing high correlations with THI estimates from INMET and good regression evaluation metrics, and can assist studies that aim to analyze the impact of heat stress on livestock production in Brazil, providing additional data to complement the existing information available in the INMET database.

Assessing dual-energy X-ray absorptiometry prediction of intramuscular fat content in beef longissimus steaks.

This study assessed the capability of dual-energy X-ray absorptiometry (DEXA) to predict intramuscular fat (IMF) content of beef longissimus steaks against chemical IMF as the gold standard. DEXA performance of fat% prediction was assessed using a leave-one-out cross validation method among Angus and Nellore steaks, which generated a chemical fat% range of 14.05-36.82% and 2.46-7.84%, respectively, and using pooled data. There was a significant positive association between DEXA predicted fat and chemical fat content. However, higher precision was found for pooled data (R2 = 0.95, RMSECV = 1.95) and Angus (R2 = 0.75, RMSECV = 2.39) than Nellore (R2 = 0.15, RMSECV = 1.22) group. Accuracy also had the same response with average slope values close to 1 for pooled data and Angus and a lower value (0.42) for Nellore group. DEXA precisely predicts IMF content across a wide range of fat content. However, its precision and accuracy of prediction within low-fat content samples are lower than in high-fat content.

Skeletal Muscle Development in Postnatal Beef Cattle Resulting from Maternal Protein Restriction during Mid-Gestation.

We aimed to investigate the effects of maternal protein restriction during mid-gestation on the skeletal muscle composition of the offspring. In the restriction treatment (RES, n = 9), cows were fed a basal diet, while in the control (CON, n = 9) group cows received the same RES diet plus the protein supplement during mid-gestation (100-200d). Samples of Longissimus dorsi muscle were collected from the offspring at 30d and 450d postnatal. Muscle fiber number was found to be decreased as a result of maternal protein restriction and persisted throughout the offspring's life (p < 0.01). The collagen content was enhanced (p < 0.05) due to maternal protein restriction at 30d. MHC2X mRNA expression tended to be higher (p = 0.08) in RES 30d offspring, however, no difference (p > 0.05) was found among treatments at 450d. Taken together, our results suggest that maternal protein restriction during mid-gestation has major and persistent effects by reducing muscle fiber formation and may slightly increase collagen accumulation in the skeletal muscle of the offspring. Although maternal protein restriction may alter the muscle fiber metabolism by favoring the establishment of a predominant glycolytic metabolism, the postnatal environment may be a determinant factor that establishes the different proportion of muscle fiber types.