Climate change, with a constant increase in the Earth temperature, negatively affects livestock production and health. This paper will focus on the possible nutritional and feeding strategies to mitigate the negative impact of heat stress (HS) on ruminants. The first nutrient interacting with hot weather conditions is fibre and its digestibility. It is well recognised how fibre may affect voluntary dry matter intake (DMI), chewing and ruminating activity. A possible dietary strategy to counteract the reduced DMI under hot environment is represented by the increased diet energy concentration, protein supply and essential aminoacids. Mineral feeding under HS condition must cover the supply of each nutrient as consequence of altered turnover, and the needs related to buffer requirements. Particular interest is growing in the use of Se (Se-yeast), because of its role to support the animal antioxidative defences. Water is a pivotal nutrient to cope with HS in ruminants because it plays a role in animal thermoregulation. Recently, some vitamins and feed additives were studied for their action on the animal physiology to cope with HS. Among vitamins, niacin was tested for its action on the vasodilatation in the mammalian and for its role in lipid metabolism; among feed additives, yeasts and plant extracts may exert a positive action in rumen metabolism as well as in regulation of body temperature.

In the last 50 years, the diversity of cattle breeds has experienced a severe contraction. However, in spite of the growing diffusion of cosmopolite specialized breeds, several local cattle breeds are still farmed in Italy. Genetic characterization of breeds represents an essential step to guide decisions in the management of farm animal genetic resources. The aim of this work was to provide a high-resolution representation of the genome-wide diversity and population structure of Italian local cattle breeds using a medium-density single nucleotide polymorphism (SNP) array. After quality control filtering, the dataset included 31,013 SNPs for 800 samples from 32 breeds. Our results on the genetic diversity of these breeds agree largely with their recorded history. We observed a low level of genetic diversity, which together with the small size of the effective populations, confirmed that several breeds are threatened with extinction. According to the analysis of runs of homozygosity, evidence of recent inbreeding was strong in some local breeds, such as Garfagnina, Mucca Pisana and Pontremolese. Patterns of genetic differentiation, shared ancestry, admixture events, and the phylogenetic tree, all suggest the presence of gene flow, in particular among breeds that originate from the same geographical area, such as the Sicilian breeds. In spite of the complex admixture events that most Italian cattle breeds have experienced, they have preserved distinctive characteristics and can be clearly discriminated, which is probably due to differences in genetic origin, environment, genetic isolation and inbreeding. This study is the first exhaustive genome-wide analysis of the diversity of Italian cattle breeds. The results are of significant importance because they will help design and implement conservation strategies. Indeed, efforts to maintain genetic diversity in these breeds are needed. Improvement of systems to record and monitor inbreeding in these breeds may contribute to their in situ conservation and, in view of this, the availability of genomic data is a fundamental resource.

Semi-feral local livestock populations, like Maremmana cattle, are the object of renewed interest for the conservation of biological diversity and the preservation and exploitation of unique and potentially relevant genetic material. The aim of this study was to estimate genetic diversity parameters in semi-feral Maremmana cattle using both pedigree- and genomic-based approaches ($F_{IS}$ and $F_{ROH}$), and to detect regions of homozygosity (ROH) and heterozygosity (ROHet) in the genome. The average heterozygosity estimates were in the range reported for other cattle breeds ($H_E=0.261$, $H_O=0.274$). Pedigree-based average inbreeding (F) was estimated at $4.9\%$. The correlation was low between F and genomic-based approaches ($r=0.03$ with $F_{IS}$, $r=0.21$ with $F_{ROH}$), while it was higher between $F_{IS}$ and $F_{ROH}$ ($r=0.78$). The low correlation between F and $F_{ROH}$ coefficients may be the result of the limited pedigree depth available for the animals involved in this study. The ROH islands identified in Maremmana cattle included candidate genes associated with climate adaptation, carcass traits or the regulation of body weight, fat and energy metabolism. The ROHet islands contained candidate genes associated with nematode resistance and reproduction traits in livestock. The results of this study confirm that genome-based measures like $F_{ROH}$ may be useful estimators of individual autozygosity, and may provide insights on pedigree-based inbreeding estimates in cases when animals’ pedigree data are unavailable, thus providing a more detailed picture of the genetic diversity.