Breeding for longevity in Italian Chianina cattle

The objective of this thesis was to evaluate genetic aspects of longevity (LPL) in the Chianina beef cattle population in order to define how to include this trait in selection criteria. The Chianina breed has been raised for over twenty-two centuries in<st1:country-region w:st="on">Italy</st1:country-region>and today this breed is present in different countries across Europe, South and<st1:City w:st="on">Central America</st1:City>,<st1:country-region w:st="on">Australia</st1:country-region>,<st1:country-region w:st="on">Canada</st1:country-region>and the<st1:country-region w:st="on"><st1:place w:st="on">USA</st1:place></st1:country-region>. Its characteristics of somatic gigantism and rapid growth are combined with enormous resistance to harsh environmental conditions, great ease of calving and an excellent meat quality. In this breed longevity was recorded as the length of productive life (LPL), defined as years from the age at the insemination that resulted in the birth of the first calf to the date of culling or censoring. Six<span class=GramE>mo</span>were added after the last date of calving to account for the time that the calf remains with the cow. The LPL was equal to 5.97 years on average. Heritability was equal to 0.11 when both censored and uncensored data were included to estimate longevity with the survival analysis. Type traits were used as an early predictor of profitability and muscularity traits were the most important parameters for longevity among the factors studied. Cows with approximately one calf per year remained in the herd longer than cows with fewer calves.<span style='letter-spacing:.2pt'>Cows with a long LPL were more profitable than cows with short LPL. The f</span>inal score could be used as an early predictor of profitability. An increase of one day unit in LPL was associated with an increase of +0.19 €/cow per year and +1.65 €/cow on a lifetime basis. Including longevity in both the Chianina breeding index and breeding goal either using empirical or economical weights has the positive effect of increasing the response (+2.97 and +4.92 days/year respectively). Beef breeding organizations should consider the opportunity to include longevity in a future breeding scheme to increase profit and to promote the well-being and welfare of the cows