In general, the results obtained showed that BON cows have some characteristics that determine the racial pattern (RC) and breeders identify individuals that fitted to the breed profile. In turn, the average FS observed in the three subpopulations was similar (Table 2), and is supported by the value of 80 points (good) acording to ICAR (2018), and suggested that that BON cows correspond to a prototype with desirable phenotype qualification.
There are relevant phenotypic traits for producers over the years. For instance, HR and DL traits showed a rectilinear trend between the withers and the sacrum. This means that BON cows have a strong lumbar-dorsal line and reflects the influence of producers' preferences when selecting their animals, discarding cows with spinal deviations, such as lordosis (Sanchez and Iglesias, 2009).
Creole individuals stand out for their adaptive and reproductive characteristics, where, in some situations, muscle development has been a factor that reduces their use in production environments compared to specialized breeds (Arelovich et al. 2011; Armstrong et al. 2022). Efforts made by Agrosavia in recent animal selection processes generated changes in the musculature traits relationships. It can be seen that these traits in the BN and ASH subpopulations present greater similarity and are grouped with production traits, which in the case of BN include aspects related to the udder. Some producers see in this breed an ideal genetic component for milk production, as well as in crossbreeding with dairy breeds such as Holstein (Cañas et al. 2009).
An interesting result of this study for the ASH subpopulation of cows (Fig. 3C) was the clustering of body structure traits (WH, CW, HR, BL, and CD) and musculature (LW, TWD, and AW), reflecting management of the joint selection of characteristics associated with meat production. Berry et al. (2019) mentioned that the evaluation of the external view of the animal's musculature and size, in terms of structure, should have some relationship with carcass yield, which may seem reasonable that these subjectively scored traits correlate with primal cut yields.
Historically, BON cattle have adapted to the environment of the inter-Andean valleys of Colombia, especially in Antioquia region (Martínez et al. 2012), characterized by altitudes between 1500 and 2200 m.a.s.l., and one of the mountainous regions of the country. In this sense, the BON animals presented a good to excellent posture conformation for hillside grazing.
In fact, the optimal or desirable average scores of the set of legs and feet corroborate that the animals presented a normal and adequate direction of the limbs in their entire length or of the different regions separately, which allows a good physical support (de Faria et al. 2007), and symmetrical locomotion without problems when walking long distances to feed or in the time of reproduction (Góes and Pierre, 2018). Zhang et al. (2015) mentioned that animals with simple, reliable and strong legs adapt very well to the terrain in which they feed, mate and avoid predators. It should be noted that some problems or defects in the legs and feet can worsen, causing pain and suffering that implies low feed intake, loss of body condition, low fertility and production. All this involves animal welfare and, therefore, functionality (Roveglia et al. 2019). As such, care must be taken with the tolerance of certain defects at limb level (de Faria et al. 2007).
Low average udder trait scores indicated weakness in insertion and suspensory ligament, with high udders. Having poor insertion and fixation of the udder (score from 1 to 3 points) predisposes cows to abandon the herd more frequently, given that, as the anterior lobes of the udder are very close together, there is lower productivity (García-Ruíz et al. 2016; Palii et al. 2020). However, TL and TP were suitable, allowing for adequate milking or for the offspring to grasp the teats correctly at the time of suckling, and also preventing mastitis (Campos et al. 2012). This means that cows with functional udders, which are extended under the abdomen, well attached, with thin and short teats, should be selected (Simčič et al. 2021).
García-Ruíz et al. (2016) mentioned that cows with the udder floor slightly above the hock have a lower risk of being discarded than cows with the udder floor below the hock. Therefore, evaluation of cow anatomical attributes, such as udder morphology, provides an opportunity for BON breed selection programs to also target higher milk production (Sinha et al. 2021). Currently, there are no milk production records for genetic evaluations in this breed and, therefore, maternal ability variables are the only indirect criteria for this type of phenotypes.
For the three subpopulations, CW and CD were found to have intermediate scores, reducing the relative risk of discarding cows (Table 2), since those characteristics indicate sufficient space to house vital organs, such as the heart and lungs (García-Ruíz et al. 2016). Thus, for example, cows with high scores indicate broad thorax and sufficient cardiorespiratory capacity. Similarly, the relationship between CW and CD is evident in the clustering of the three BON subpopulations (Fig. 3).
The hierarchical analysis of distances between the analyzed phenotypic variables showed relationships that allow analyzing the phenotypic trend between animals according to management. However, there is clarity in the selection that is made in each subpopulation according to the functional balance in the foot angles so that the animals have an adequate movement in the paddocks.
In each subpopulation studied (BN, AGB and ASH), the selection criteria or animal management can generate differences in the frequency of the scores observed for the conformation traits. For example, some herds in BN have flat terrain whereas other have hillsides and selection criteria at the phenotypic level may be more oriented towards increasing the frequency of animals with high scores for musculature characteristics such as AW or udder traits (Table 2).
The genetic management model for AGB animals prioritizes conservation and variability over production schemes. In this case, the scores of 14 phenotypic traits are above the expected traits for selection (ASH) or breeder (BN) subpopulations (Table 2).
The animals that have the best body conformation, given the positive contribution for most of the traits, were grouped in cluster three in Fig. 2. According to de Faria et al. (2007), the identification and optimal use of superior animals with morphological evaluation using visual scoring plays a fundamental role in determining trends and promoting the selection of individuals with the appropriate biotype for the market.