Genetic correlations between type and test-day milk yield in small dual-purpose cattle populations: The Aosta Red Pied breed as a case study

Abstract

This study aimed at estimating the relationships between linear type traits and milk production in the dual-purpose Aosta Red Pied (ARP) cattle breed, by expressing type traits as factor scores with the same biological meaning of the individual traits. Factor analysis was applied to individual type traits for muscularity and udder of 32,275 first-parity ARP cows, obtaining 3 factor scores for individual muscularity (F1), udder side (F2), and udder conformation (F3). Data from 169,008 test-day records of milk, fat, and protein yield (kg), belonging to the first 3 lactations of 16,605 cows, were also analyzed. After obtaining genetic parameters for both morphological factors and milk production traits through a series of AIREML single-trait models, bivariate analyses were performed on a data set accounting for 201,283 records of 35,530 cows, to assess the phenotypic and genetic correlations among all factor scores and milk yield traits. The heritability estimates obtained proved to be moderate for both groups of traits, ranging from 0.132 (fat) to 0.314 (F1). Muscularity factor showed moderate and negative genetic correlations (ra) with udder size (-0.376) and udder conformation (0.214) factors. A low and negative ra was found between udder factors. Strong and positive ra were found among all the 3 milk production traits and F 0010 (ra≥0.597). Negative ra with milk traits were obtained for both F 0005 and F3, ranging from -0.417 to -0.221. Phenotypic correlations were lower than the genetic ones, and sometimes close to zero. The antagonism between milk production and meat attitude traits suggests that great attention should be paid in assigning proper weight to the traits, comprising functional traits such as udder conformation, included in selection indices for the dual-purpose breed. The ra obtained for factor scores are consistent with previous estimates for the corresponding individual type traits, and this confirms the possible use of factor analysis to improve type traits relevant to beef attitude.

Genetic parameter estimates for body conformation traits using composite index, principal component, and factor analysis

“…In the present study, the heritability estimates of both PC and factors obtained were in agreement with the estimate of the heritability of the composite traits with PC1 and F1 (BC) showing the highest heritability and PC4 and F4 (FL) with the lowest estimate. These results are in accordance with the report of Mazza et al (2016a,b) where similar findings were disclosed for both individual traits and the multivariate techniques used in this study and this affirmed the possible use of both PCA and FA in animal breeding (Macciotta et al, 2012;Mazza et al, 2016b).…”

Are cheese-making properties of dual purpose cattle impaired by highland grazing? A case study using Aosta Red Pied cows

“…Fontina cheese (FC), a PDO product, is manufactured from fullfat and unpasteurised ARP milk, from LO or HI pastures, within 2 h after every single morning and evening milking (Mazza et al 2016). For this purpose, milk from 47 ARP cows was repeatedly sampled from May to July, including both LO to HI pastures.…”

Multivariate analysis of body morphometric traits in conjunction with performance of reproduction and milk traits in crossbred progeny of Murrah × Jafarabadi buffalo (Bubalus bubalis) in North-Eastern Brazil

“…PCA has been widely used in animal production in order to understand the relationship between several traits that are of economic interest, and to understand the contribution of each trait in each PC [13][14][15][16][17][18][19][20][22][23][24][25][26][27]57,58]. In this study, we verified that the first six PCs explained 82.14% of the total variance, and the importance of each body measurement in the composition of these six PCs were determined by the correlations between the original variables and PCs, such as their weighting coefficients ( Table 2).…”

“…Therefore, the selection of animals while considering the association between body morphometric traits and productive/reproductive traits can be effective for obtaining suitable biotypes for each production system. Research has shown the association between biotypes, and productive and reproductive traits [3,[6][7][8][9][10][11][12][13][14][15][16][17][18][19]. However, there are limited studies examining functional biotype and their relationship with productive/reproductive in the buffalo.…”

“…This technique aims to study several traits simultaneously, which can be difficult to measure or hard for selection programs to understand, especially when there is a negative genetic correlation between them [14]. Multivariate techniques, such as principal component analysis (PCA) and canonical correlation analysis (CCA), have been widely used in animal production study [7,[12][13][14][15][16][17][19][20][21][22][23][24][25][26][27][28][29]. PCA has been used to clarify the structural relationship between different traits and to eliminate redundant traits, thus reducing the sample size of original set of variables [30,31].…”