The assessment of the prevalence of Subclinical Mastitis (SCM) in dairy farms is essential to validate the health status of the mammary gland. The aim of the study was to assess the prevalence of SCM in dual purpose livestock systems in Arauca, Colombian Orinoquia, through the analysis of the values found by the field diagnostic tests California Mastitis Test (CMT) and Electric Conductivity (EC). Milk samples were taken from the individual mammary quarters of 481 cows. The general prevalence, per affected room and the total number of rooms was determined according to the values obtained for each test using two methods of analysis. An ANOVA was performed to determine the difference between prevalence’s, a correlation analysis, and an analysis of sensitivity and specificity. The general prevalence was similar between the tests (CMT = 31.4%; EC = 29.7%) (p > 0.05). The prevalence of the total quarters was lower with EC (11.3% vs 14.2%) (p < 0.05). The correlations between tests were significant, but with low values (rs = 0.20-0.25). CMT and EC test concordance showed a sensitivity between 0.35-0.45 and a specificity of 0.75-0.90. The two tests showed positive results in detecting the same animals with or without the presence of the infection, although some animals that were positive for one test were not positive for the other test. The test EC classified animals and their quarters as SCM positive or negative in a more similar way to that obtained with CMT. The two diagnostic tests showed a general low prevalence of SCM in the livestock systems evaluated.

Productive and nutritional evaluations of native grasses are usually scarce, limiting their use in the feeding of herbivorous species. This study aims to determine the forage yield and nutritional value of native grasses from the floodplain “banks” ecosystem in the Colombian Orinoquia. Four native grasses (Paspalum plicatulum, Axonopus compresus, Axonopus purpussi, and Paspalum spp.) and a “control” grass (introduced Brachiaria hybrid cv. Mulato) were sown and sampled at 30, 40, and 50 days of age. On each sampling date, biomass production in a 1 m2 frame was estimated, and the chemical composition was analyzed using near-infrared spectroscopy. Data analysis included repeated measures analysis, correlations, and multiple linear regression. The grasses’ nutritional characteristics varied as follows: dry matter (DM, 0.9–2.5 ton/ha), crude protein (CP, 4.3–10.2%), neutral detergent fiber (NDF, 61–73.9%) ash (3.2–8.7%), and dry matter digestibility (DMD, 50.8–56.3%). P. plicatulum achieved comparable forage production to that of the “control” grass. A. purpussi, Paspalum sp., and P. plicatulum presented similar CP and ash contents, and a higher Ca:P ratio. Regression analysis indicated that DMD was affected by the CP and acid detergent fiber (ADF) levels. These native grasses constitute promising nutritional alternatives that must be considered in the region’s livestock-production systems; however, detailed studies to evaluate animal performance and consumption are still required.

Native plants constitute an enormous source of nutrients for grazing animals, although their use has been limited due to the lack of knowledge about its properties. The aim of this research was to evaluate the nutritional characteristics of native plants from flooded savannas ecosystem. Seven transects (290 km) were carried out through the montane forests, gallery forests and open savannah ecosystems. A total of 42 plant species were collected (22 arboreal, 13 shrubs, 5 climbing and 2 herb plants) and their nutritional composition and digestibility were evaluated. Data analysis included univariate and multivariate methods. Nutritional composition and digestibility varied among the groups of arboreal, shrub, climbing and herb species. At an individual level plants such as G. americana, C. cf minor-grandiflora and M. nobilis, A.Jahnii, P. hispidium, I. carnea, S. reticulate, H. furcellatus, and C. erosa stood out by their protein, ash, and digestibility. At a group level, a mixed of 19 plants presented the highest digestibility, and the lowest fiber fraction constituted a promising forage alternative. Data variability was explained in the 47% by protein, ash, digestibility, and the different fiber fractions variables. Further studies related with the animal acceptability, performance and the presence of secondary metabolites are needed before being fully recommended.

Vasconcelos et al 2020). Animal's body temperature is traditionally estimated through rectal and vaginal measurements; however, alternative methods like tympanic temperatures (TT) also constitute a reliable measure since some studies reported no statistical difference with rectal temperatures (Sellier et al 2014;Shu et al 2021) and high correlation with vaginal temperature (r = 0.77; Bergen and Kennedy, 2000). The differences associated with the anatomical sampling point and its response time were also validated in other studies (Scharf et al 2011;Sellier et al 2014;Godyń et al 2019). TT is an attractive alternative measure Abstract The present study aimed to analyze large volumes of tympanic temperature (TT) data to identify its use as a physiological indicator of climatic conditions and its relationship with milk production in grazing cows under tropical lowland conditions. Three dairy farms and 21 multiparous early lactation cows were included in the study. Seven animals were equipped with tympanic temperature wireless sensors within each farm, and permanent information was collected hourly for 22 days on average. Ambient temperature (AT), relative humidity (RH), wind speed (WS), precipitation (PP), and THI information were obtained from meteorological stations located close to each farm. Statistical analyses included Spearman correlations and random coefficient regression models (P < 0.05). TT presented moderate and significant correlations with AT (0.35 to 0.49), SR (0.25 to 0.32), THI (0.35 to 0.49), and RH (-0.35 to -0.49). Climatic variables like AT, PP, SR, and WS were the most contributing factors to TT prediction (R 2 =0.42 to 0.86). Grazing dairy cows in tropical scenarios accumulate heat during the day and dissipate it at nighttime, although higher producing animals deal with more problems to reach thermal homeostasis. Correlations between TT and daily milk production varied according to animal yield; however, higher TT values were related to the most productive cows. The effect of TT on milk production prediction was not conclusive among farms, possibly by animal management or others characteristics of the systems. TT determination through remote sensors allows a reliable diagnosis of the physiological temperature response to climatic conditions.

Milk is the natural food with the highest biological quality for the human population and its production can be affected by several sanitary factors and management conditions. With the objective of identifying influence factors on milk compositional and sanitary quality in a region with wide productive potential in the Colombian Orinoquia, an experiment was carried out in two contrasting climatic seasons. For the milk compositional analysis, samples of daily production from 30 dual-purpose systems were analyzed. Similarly, the udder sanitary status of 300 cows was studied using the California Mastitis Test (CMT). Data analysis included mixed models, Pearson correlations, frequency tables, and the Kruskal–Wallis test. The results showed that the total daily milk production of the farm and the season influenced the milk compositional quality. The farms with milk productions lower than 100 kg/day presented the highest levels of protein, lactose, solid non-fat (SNF), and density, while in the rainy season, the milk quality was higher compared to the dry season. The CMT test indicated that only 7.6% of the evaluated mammary quarters presented two or more degrees of positivity. There is an opportunity to improve the milk compositional quality by improving the nutritional offer for animals during the year. The low CMT positivity indicates that, in the calf-at-foot milking system, the presence of subclinical mastitis is not a determining variable in milk production.