Background: Mastitis is a major disease in dairy production, causing economic losses and increasing concern due to antimicrobial-resistant bacteria. The presence of resistant Staphylococcus spp. in raw milk from clinically healthy animals may represent a potential public health risk and a challenge for control strategies under a One Health framework. Objective: To evaluate antimicrobial resistance patterns and resistance genes in Staphylococcus spp. isolated from raw milk of clinically healthy cows, goats, and ewes from three dairy farms included in this study. Methodology: Seventy-five isolates (25 per species) were analyzed using disk diffusion antibiograms and PCR detection of blaZ, mecA, ermB, and tetK genes. Phenotypic–genotypic agreement and interspecies differences were statistically evaluated. Results: High phenotypic resistance to β-lactams was observed, especially in cows (ampicillin 96%, penicillin 92%) and ewes (penicillin 60%). Oxacillin resistance was higher in goats and ewes (52%) than in cows (8%). Resistance to erythromycin and tetracycline was moderate to low. Gene detection showed high prevalence of mecA (84–100%) and blaZ (80% in cows and goats; 20% in ewes), with significant interspecies differences in blaZ and tetK (p < 0.001). Overall phenotype–genotype agreement was low, although blaZ showed the highest diagnostic value. Frequent codetection of resistance genes was observed among isolates, indicating the coexistence of multiple resistance determinants within the same bacterial populations. Implications: The low phenotype–genotype concordance highlights limitations of relying on a single diagnostic approach and suggests the need for integrated surveillance combining phenotypic and molecular tools. Conclusion: Antimicrobial-resistant Staphylococcus spp. are widely present in raw milk from clinically healthy ruminants, with significant interspecies differences. The present study revealed marked differences in antimicrobial resistance profiles and resistance gene distribution among Staphylococcus spp. isolated from cows, goats, and ewes. The low phenotype–genotype concordance observed for several antibiotic–gene pairs highlights the complexity of antimicrobial resistance and supports the complementary use of phenotypic and molecular approaches for surveillance and characterization of resistant isolates.
Background: Small-scale dairy production systems play a vital role in the social economy, as they help alleviate rural poverty by providing a stable income for farming families and accounting for over 30% of national milk production. However, they face major challenges, particularly in terms of profitability and sustainability, largely due to their dependence on external inputs, and now climatic conditions are further complicating the situation for production units, particularly drought and a lack of irrigation water. Objective: The objective of this study was to evaluate the productive performance of dairy cows fed three feeding strategies based on maize silage combined with sunflower-ebo silage in small-scale dairy production systems in the High Valleys of Central Mexico. Methodology: Six multiparous Holstein cows were arranged in a 3×3 Latin square design repeated twice. Three treatments comprising different combinations of maize silage and sunflower-ebo silage were evaluated: T1 = 20% maize silage + 80% sunflower-ebo silage; T2 = 30% maize silage + 70% sunflower-EBO silage; T3 = 40% maize silage + 60% sunflower-EBO silage. Results: About production performance, there were no statistically significant differences (P>0.05) between treatments for any of the variables assessed. As for the chemical composition of the milk, the mean fat content ranged from 42.10 to 43.10 g/kg, whilst the protein content ranged from 30.83 to 31.12 g/kg, and lactose between 46.57 and 46.95 g/kg; no significant differences were observed between treatments (P>0.05). Statistically significant differences (P<0.05) were found for PC. No statistically significant differences (P>0.05) were found for NDF, ADF, IVDMD and eEM. Conclusions: The use of alternative forage crops such as vetch (Vicia sativa L.) or sunflower (Helianthus annuus), in combination with maize silage, is a viable option for these production systems.
Background. Seed dispersal and establishment are key processes for tropical forest regeneration; however, little is known about them in tropical deciduous forests. Ctenosaura pectinata disperses seeds, but it is unknown whether it scarifies them during this process. Objective. To evaluate the effect of passage through the digestive tract of C. pectinata on the seed coat, germination, and seedling establishment of Diospyros salicifolia and Pithecellobium dulce, two tree species from the tropical dry forest of the Oaxacan coast. Methodology. Sixty-six specimens were fed ad libitum with ripe fruits of both species. Feces were collected, seeds were recovered, and their length, width, thickness, as well as the width of the raphe, hilum, and fissure line were measured. The final germination percentage, average germination time, germination rate coefficient, and seedling growth parameters were evaluated. Uningested seeds were used as a control. Data were analyzed using Student's t-tests (p<0.05). Results. Passage through the digestive tract caused scarification (p<0.05) of the seed coat. In D. salicifolia, it increased the width of the raphe (82.5%) and the hilum, while in P. dulce, it increased the opening of the fissure line (0.21 mm). However, it reduced final germination (D. salicifolia: 54% vs. 83%; P. dulce: 12.2% vs. 80%) and viability (43% vs. 56%). P. dulce showed accelerated germination (germination rate coefficient: 44.2% vs. 28.8%) and a shorter average germination time. Seedling establishment was not affected (p>0.05); however, an increase in root diameter was observed in D. salicifolia seedlings grown from seed that had passed through the digestive tract. C. pectinata acts as an effective seed disperser by scarifying seeds; its role is species-dependent: it promotes germination rate in P. dulce but reduces final germination in both species. Implications. The consumption of D. salicifolia by adult C. pectinata is reported for the first time. Conclusion. The passage of seeds through the digestive tract of the black iguana scarifies the seed coat and modifies the germination parameters of both tree species, highlighting its ecological role in seed dispersal.
Background. Malpighia glabra is a native fruit species, with great nutritional and economic potential to which several biological activities are attributed. However, it presents serious problems related to its germination. Objective. To evaluate the physiological response of M. glabra seeds and seedlings subjected to four pregermination treatments. Methodology. The pregerminative treatments used were: 1) control (water), 2) immersion in water at 60°C for 5 min, 3) immersion in water for 48 h, 4) immersion in gibberellic acid (AG3) for 48 h. Germination, emergence and growth of seedlings were evaluated up to 45 days. Results. Immersion in AG3 caused delays in germination, but had a positive effect on the size and dry weight of the leaves. The treatments that resulted in the highest emergence value were water immersion with 45% and hot water immersion with 40%, they also resulted the highest values in dry weight of stem and root. Implication. Pregerminative treatments are an accessible and economical option to improve the germination of M. glabra seeds. Conclusion. The treatments did not influence final germination percentage. However, water immersion and hot water immersion obtained the highest percentages of emergence and dry weight of stem and root.
