A total of 352596 results of the test day milk controls (TD), as well as the climatic variables of Temperature and Relative Humidity combined in an index known as ITH, carried out in 5 stables in the Lima region, between January 2006 and December 2018, were available for this study. This database was represented by the TD of 11876 Holstein daughters of 8439 dams and 321 sires and was studied by different random regression models with the objective to estimating the genetic relationships between TD and ITH as an indicator of heat stress (HS). The results indicated that heritability (h2 ), along the ITH scale shows a slightly upward trend (h2 = 0.113±0.01 to 0.187±0.02) until reaching its highest values in the so-called thermal stress zone (ITH>=68 to ITH=77). The genetic correlations (rg) were close to the unit between adjacent or very close ITH levels and decreased as the difference...

The results of 443 763 periodic controls of daily milk production (DMP) carried out between January 2006 and December 2018 in five Holstein dairy farms in the Lima region were related to meteorological information (maximum and minimum temperature and relative humidity), under temperature-humidity indexes (THI) to represent the current state and the trends of the relationships between DMP and possible thermal stress (TS) identified by the level of THI. The DMP levels along the THI levels showed a response curve with a THI tolerance zone where there is little variation in DMP and threshold point at THI >68 from which DMP is reduced at a rate of -0.413 kg of milk per unit of increase in THI. Analyzed as a whole, this negative response represents an impact of -365 kg of milk per cow per year. It is concluded that all the trends are consistent in pointing out antagonism between TS and DMP,...

The study aimed to estimate the components of (co) variance and genetic parameters for growth traits as birth weight (BW), weaning weight (WW) and weight at 16 months of age (W16) of calves of the creole breed Costeño con Cuernos, born between 1989 and 2011 in a herd located in the northeast of Colombia. For this, 3060, 2594 and 1990 BW, WW and W16 records were analyzed, respectively. Single-trait (UNI) and multi-trait (MT) models were used. Six variants were evaluated with the UNI model, in all cases the random effect of the animal was included and the rest of the models alternated the maternal effect, the effect of the permanent environment and the relationship between the direct and maternal effect. Goodness of fit was determined using the information criteria of Akaike (AIC), Bayesiana (BIC) and LogL. For BW and WW models involving direct, maternal, and permanent maternal environmen...

The study aimed to estimate the components of (co) variance and genetic parameters for growth traits as birth weight (BW), weaning weight (WW) and weight at 16 months of age (W16) of calves of the creole breed Costeño con Cuernos, born between 1989 and 2011 in a herd located in the northeast of Colombia. For this, 3060, 2594 and 1990 BW, WW and W16 records were analyzed, respectively. Single-trait (UNI) and multi-trait (MT) models were used. Six variants were evaluated with the UNI model, in all cases the random effect of the animal was included and the rest of the models alternated the maternal effect, the effect of the permanent environment and the relationship between the direct and maternal effect. Goodness of fit was determined using the information criteria of Akaike (AIC), Bayesiana (BIC) and LogL. For BW and WW models involving direct, maternal, and permanent maternal environmen...