Milk protein content represents a key economic trait in dairy production, yet the genetic architecture underlying this trait remains unexplored in Romanian dual-purpose cattle breeds. This study conducted a genome-wide association analysis for milk protein content in 313 Romanian Simmental (n = 271) and Romanian Brown (n = 42) cows belonging to the Research and Development Station for Bovine Arad, Romania. Following quality control, 33,531 SNPs were tested for association with protein percentage adjusted for other effects (breed, days in milk, season, year, parity) using linear regression with the first five principal components as covariates to control population stratification. Although no SNP reached genome-wide significance (p < 5 × 10⁻⁸), one SNP achieved significance (p < 2.98 × 10⁻⁵) and seven additional SNPs exceeded the nominal threshold (p < 1 × 10⁻⁴) across six chromosomes. The strongest association (p = 9.56 × 10⁻⁶) mapped to chromosome 25 near C7orf61. Biologically relevant candidate genes included KLF6 on chromosome 13, previously associated with milk traits in Chinese Holstein, and AHCYL1 on chromosome 3, involved in calcium homeostasis. These findings provide initial insights into genomic regions influencing milk protein content in Romanian dual-purpose cattle, though validation in larger cohorts needs to be carried out.

Heat stress (HS) is a critical challenge in dairy farming, affecting metabolism, milk production, and overall cow health. This review explores the impact of HS on fatty acid metabolism, milk fatty acid composition, and lipid metabolism shifts under elevated temperatures. While HS typically induces a negative energy balance (NEBAL), studies reveal paradoxical findings regarding non-esterified fatty acids (NEFAs) dynamics, with some reporting increased fat mobilization and others showing blunted NEFA responses. Additionally, short- and medium-chain fatty acids (SCFAs and MCFAs) decline under heat stress, whereas certain long-chain fatty acids (LCFAs), particularly unsaturated fatty acids (UFAs) like C18:1 cis-9, increase, suggesting their role as biomarkers for HS adaptation. The primary tools in this review are the academic databases (PubMed and Google Scholar). These databases were used for literature retrieval based on defined search terms and Boolean operators. The review also highlights genetic variations in fatty acid responses to HS and the potential of specific fatty acids in monitoring heat stress effects. Understanding these metabolic alterations is crucial for developing strategies to mitigate the adverse effects of heat stress in dairy cattle.

The evaluation of external pelvimetry measurements and the genetic factors influencing them is essential for improving morphological characteristics and reproductive performance in cattle. This study represents the first comprehensive analysis of the association between single nucleotide polymorphisms (SNPs) and external pelvimetry traits in Romanian Simmental cattle, a breed recognized for its distinctive pelvic morphology. The relationship between single-nucleotide polymorphisms (SNPs) and external pelvimetry traits—including croup height (CH), buttock height (BH), croup width (CW), rump angle (RA), and croup length (CL)—was examined in Simmental cows. From an initial set of 110 SNPs, 33 markers were retained after applying quality control filters, including a minor allele frequency (MAF) greater than 0.05 and Hardy–Weinberg equilibrium. These SNPs, located on multiple chromosomes, were identified within intronic, exonic, or regulatory regions of relevant genes such as CLSTN2, DPYD, FBXL7, FBXL13, SEMA6A, RUNX2, FSTL4, DST, DCBLD2, FRMD6, CAV2.3, ABL2, SH3BP4, RSBN1L,and SAMD12, suggesting that these genetic variants may influence the development and morphology of the pelvic bones. Statistical analysis revealed significant relationships between certain allele variants and croup measurements, highlighting that the presence of alternative alleles can modify their morphological traits. Notably, the G allele in CLSTN2 reduced croup height by 5.74 cm (p = 0.0227), while the T allele in RUNX2 decreased rump angle by 4.49° (p = 0.0119).

Heat stress poses a significant challenge to dairy cattle by disrupting physiological homeostasis, reducing productivity, and altering nutrient metabolism. A central adaptive mechanism to HS involves enhanced proteolysis and mobilization of skeletal muscle, supplying amino acids for energy production via gluconeogenesis. This review synthesizes current findings on the effects of HS on intracellular, circulating, and milk amino acid profiles in dairy cows, with an emphasis on identifying potential biomarkers of thermal stress. Multiple studies demonstrate that heat stress modulates amino acid metabolism across tissues, with notable compartment-specific changes. Intracellular concentrations of certain amino acids such as proline, glutamine, and valine often increase under heat stress, while their systemic and milk levels tend to decline, suggesting increased cellular retention and utilization. Essential AAs like lysine, methionine, and isoleucine consistently decrease in blood and milk, reflecting compromised availability and altered mammary uptake. Moreover, heat stress impacts amino acids involved in immune modulation (e.g., threonine), nitrogen metabolism (e.g., arginine, citrulline, ornithine), and neurotransmitter biosynthesis (e.g., Triptophan, Tyrosine), underscoring their regulatory roles in stress adaptation. The differential response of amino acids across biological compartments highlights the complexity of their metabolic regulation under heat stress. Milk and blood amino acid profiling emerges as a promising tool for monitoring thermal stress, with lysine, glutamine, and proline among the most responsive candidates. Overall, the evidence underscores the value of targeted AA analysis for understanding and potentially mitigating the metabolic impacts of heat stress in dairy cattle.

Reproductive efficiency in cattle is influenced by multiple factors, including pelvic conformation. This study aimed to provide a descriptive analysis of pelvimetry measurements in 152 Simmental cows, focusing on the variation of key pelvic dimensions. Pelvic traits such as croup height, croup length, croup angle, buttock height, buttock width, and ilium width were measured and analyzed. The average values recorded were 143.73 cm for croup height, 54.25 cm for croup length, and 56.68 cm for croup width. Most measurements showed moderate variability, with values generally concentrated around the mean. The findings contribute to a better understanding of external pelvic morphology in Simmental cows and may support selection strategies aimed at improving reproductive performance.

Heat stress, indexed by the Temperature–Humidity Index (THI), can alter milk composition; we aimed to quantify the association between daily THI and milk fat (%) and lactose (%) in Romanian Simmental and Romanian Brown cows using routine test-day records. We conducted a retrospective, repeated-measures study of 20,564 test-day observations from 1,123 cows (2014 to 2024), linking each control to same-day THI (observed range ≈28.5–78.7). Linear mixed-effects models with a random intercept for cow included a THI×month interaction and adjustments for breed, parity, and a smooth term for days-in-milk; effects are reported per +10 THI. Results showed season-dependent responses. For fat, higher THI was associated with decreases in mid-summer and late winter (e.g., January −0.12, February −1.09, July −0.21, August −0.75 per +10 THI), but with increases across much of spring and autumn (e.g., March +0.21, April +0.19, May +0.47, September +0.78, October +0.08, November +1.14, December +0.12). For lactose, associations were predominantly negative year-round, with small exceptions (e.g., March +0.03; April ~0): decreases were observed in January −0.047, February −0.171, May −0.111, June −0.135, July −0.064, August −0.097, September −0.121, October −0.050, November −0.048, and December −0.095 per +10 THI. A pooled comparison confirmed concurrent reductions in both fat and lactose during warm months (June–August), whereas outside summer, fat generally increased with THI while lactose remained mildly negative. In conclusion, rising THI is linked to a summer depression of milk fat and modest, broadly negative shifts in lactose; month-specific interactions highlight the importance of modeling seasonal context when evaluating milk-quality resilience in these breeds.