## 4 Discussion
Thus, in general, these studies agree that there is a decrease in productive performance due to the effect of inbreeding on milk production traits such as Total Liters of Milk (TLM), TFAT, and TPROT, similar to the results obtained in our study except for TLM and increased values of SCC. In our study, we found neither a decrease in TLM nor an increase in SCC possibly because these parameters could be negatively affected in subsequent lactations due to the stabilization of productivity and increases in the inbreedingcoefficient [27]. Another explanation is the fact that some breed traits, crosses, genetic lines, or isolated animal populations with different degrees of inbreeding could be differentially more affected by ID than others [42]. Another parameter affected by the degree of inbreeding in the present work was blood urea concentration. A dietary imbalance between energy/raw protein produces reproductive and production problems [43]. In general, the variability of blood urea levels is high and depends on intrinsic (genetic) and extrinsic (dietary) factors [44; 45]. Results published by other authors showed that as milk production increases, urea levels increase and SCC levels decrease, suggesting that selection based on production performance increases the urea levels and therefore it can be considered a characteristic feature of high-producing animals [46]. However, in the present study, in spite of the urea increasing significantly in HI compared to LI, the increase of TLM was not significantly different between groups. The only genomic-associated, reproductive parameter affected by the degree of consanguinity was DCEG. This parameter is important because it is part of the total Fertility Performance Index (FIG). It shows the tendency to have more or fewer problems during delivery in the female offspring of a given site. In the present study, differences were observed between the LI and HI groups, being DCEG in the latter group a strongly affected parameter. This fact was corroborated by other authors who determined that inbreeding rates have a negative influence on the ease of delivery [27; 37]. In contrast, other studies found that the degree of inbreeding did not have a significant effect on ease of calving, although they did show a significant effect on fetal death [47; 48; 49]. Even though these studies seem to be contradictory, we speculate that the risk of fetal death may affect the prevalence of difficult deliveries. One possible cause would be the absence of fetal signals for labor initiation resulting in uterine atony and subsequent dystoxia [50]. Regarding the effect of inbreeding on reproductive phenotypic parameters, several studies have observed a deterioration in fertility as a gradually increasing problem over the last few decades, especially in dairy cattle [10; 16; 26; 27; 31; 37; 47; 48; 51; 52; 53]. In the present work, carried out in high-producing primiparous cows, the effect of the degree of inbreeding was reflected in the NSCC, a fact that shows a greater deterioration of fertility in animals belonging to the HI group. Studies in purebred Holstein-Friesian cows and crosses have shown a decrease in fertility traceable to the need for more inseminations per animal (up to 1 more per multiparous cow) [29]. In the present work, this fact is particularly evident in primiparous cows, indicating a notable effect of the degree of consanguinity on fertility, independently of the number of births. According to [PERSON] et al. [31], homozygosity derived from heritability of identical haplotypes from both parents is associated with ID, adversely affecting fertility traits. Another parameter affected in the present study was the CCI, which is influenced by environment, husbandry and genotypic factors [26]. Considering that in our study all the animals were handled similarly and kept in the same environment, we hypothesize that the deterioration of the CCI may be due to a higher degree of inbreeding as reflected by the animals of the HI group.