Evaluating Relationships among Immature Measures of Size, Shape and Performance of Beef Bulls. I. Principal Components as Measures of Size and Shape in Young Hereford and Angus Bulls

Brown, Jacquelyn A.; Brown, C. J.; Butts, W. T.

doi:10.2527/jas1973.3661010x

Cited by 49 publications

(33 citation statements)

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“…A trait with a large loading coefficient contributes more to the factor than a trait with a small one (Sieber et al, 1987). Once the loading coefficients are determined, with a varimax rotation in this case, one should try to make an interpretation of the factors by trying to confer a biological sense to the latent factor (Brown et al, 1973). The varimax rotation criterion was first introduced by Kaiser (1958) and it is known as such because it maximizes the sum of variances of the squared loadings (squared correlations between variables and factor).…”

Section: Discussionmentioning

confidence: 99%

Factor analysis for genetic evaluation of linear type traits in dual-purpose autochthonous breeds

Mazza

Guzzo

Sartori

et al. 2016

Animal

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Factor analysis was applied to individual type traits (TT) scored in primiparous cows belonging to two dual purpose Italian breeds, Rendena (REN; 20 individual type traits evaluated on 11 399 first parity cows), and Aosta Red Pied (ARP; 22 individual type traits evaluated on 36 168 primiparous cows). Six common latent factors (F1 to F6; eigenvalues ⩾ 1) which explained 63% (REN) and 58% (ARP) of the total variance were obtained. F1 included TT mainly related to muscularity, and F2 to body size. The F3 and F4 accounted for udder size and conformation, respectively. F5 included rear legs and feet. Biological significance for F6 was not readily obtained. Moderate to low heritability were estimated through REML single-trait analysis from factor scores (from 0.22 to 0.52 in REN, and from 0.08 to 0.37 in ARP). The greatest heritability values were estimated for body size and muscularity (0.52 and 0.37 for body size; and 0.40 and 0.32 for muscularity in REN and ARP, respectively). As expected, rank correlations, obtained considering estimated breeding values derived from best linear unbiased prediction analysis on the individual TT and factor score, showed similar coefficients to those observed in the factor analysis following loading of TT within each latent factor. These results suggest the possibility to implement the factor analysis in the morphological evaluation, simplifying the information given by the type traits into new variables useful for the genetic improvement of dual purpose cattle.

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Section: Discussionmentioning

confidence: 99%

Factor analysis for genetic evaluation of linear type traits in dual-purpose autochthonous breeds

Mazza

Guzzo

Sartori

et al. 2016

Animal

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“…Linear body measurements (LBM) can be used in assessing growth rate, feed utilisation and carcass characteristics in farm animals (Brown et al, 1973). Linear body measurements are divided into skeletal and tissue measurements (Essien & Adesope, 2003).…”

Section: Introductionmentioning

confidence: 99%

Charaterisation of Zulu (Nguni) sheep using linear body measurements and some environmental factors affecting these measurements

Kunene¹,

Nesamvuni²,

Fossey³

2008

SA J. An. Sci.

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Data on linear body measurements (LBM) of ca. 100 Zulu sheep raised under extensive management systems at four sites in northern KwaZulu-Natal were collected over a period of 2.5 years (October 2000 to May 2003. Data were used to quantify the live weight (LW), heart girth (HG), wither height (WH) and scrotum circumference (SC) of sheep in different age groups as well as the effects of some environmental factors on their LBM. Teeth numbers were used to estimate the age of sheep. The variation in LBM was influenced significantly by the location where an animal was raised and by its age. Mature rams that have three and four pairs of incisors had LWs of 37 and 38 kg, HG of 79 and 80 cm and WH of 65 and 64 cm, respectively. Mature ewes had LWs of 30 and 32 kg, HG of 76 cm and WH of 62 and 61 cm. Differences of 15 kg, 18 kg and 22 kg in LW among sheep with full sets of milk teeth and 28 kg, 35 kg and 40 kg among mature sheep were found between populations. The SC increased with age in mature rams (three and four pairs of incisors) and was 27 cm as compared to 18 cm for younger rams. Ear size ranged from ear buds to large ears of 9 -14 cm. However, type of ear-length was found not to have any particular influence on the variation in LBM of Zulu sheep. It was concluded that an investigation of genetic variation between the populations would be necessary to develop effective conservation and utilization programmes and strategies for the breed. _______________________________________________________________________________________

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“…Brown et al (1973) provides an example of the interpretation of principal components. The correlation matrix and standardized variates are normally used in the calculation of principal components when the traits measured are in different units or are largely different in magnitude.…”

Section: Methodsmentioning

confidence: 99%

“…The magnitude and sign of the coefficients within a given component determines the importance and grouping, respectively, of the i th measurement within that component (Brown et at., 1973). Within a component, measurements that are weighted by large coefficients are more important than those weighted with small coefficients.…”

Section: Methodsmentioning

confidence: 99%

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An Analysis of the Dependency Structure between a Gilt's Prebreeding and Reproductive Traits. II. Principal Component Analysis

Young

Johnson

Omtvedt

1977

Journal of Animal Science

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SUMMARYSeventeen variables measured before breeding and three measures of reproduction were taken on 339 purebred Duroc, Hampshire and Yorkshire gilts and 192 two-breed cross gilts resulting from matings among these breeds. Eight principal components accounted for 90% of the dependency structure existing among the 17 traits measured before breeding. Two principal components accounted for 97% of the dependency structure existing among the three reproductive traits.The first principal component (PCll) from the prebreeding traits was a general measure of growth ability and accounted for 28% of the variation in the 17 measurements. The second principal component (PC12) contrasted slow growing gilts from fast growing litters with fast growing gilts from slow growing litters and accounted for 14.5% of the total variation. The heritability for PC11 was .71 and indicates that selection for gilts with high values for PCll (above .average growth) would be very successful.The first principal component (PC21) from the reproductive traits contrasted gilts having large numbers of embryos and good embryo survival with gilts having few embryos and poor embryo survival. The second principal component (PC22) contrasted gilts having high ovula- tion rates and poor embryo survival with gilts having low ovulation rates and good embryo survival. PC21 and PC22 accounted for 57.2% and 39.5%, respectively, of the dependency structure existing between ovulation rate, embryo numbers and embryo survival rate.Based on the correlations of principal components from growth traits with principal components from reproductive traits, the following conclusions were made: If litter averages are indications of the genetic potential of a gilt selected from that litter, then gilts with a high genetic potential (good litter averages)that exhibit that potential (good individual performance) have high PCll values and are genetically superior for ovulation rate but are genetically inferior for embryo survival rates (high PC22 values). Gilts with a good genetic potential (good litter average) that fail to meet that potential (poor individual performance) have high PC12 values and are genetically inferior for ovulation rate but genetically superior for embryo survival rate (low PC22 values).

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Evaluating Relationships among Immature Measures of Size, Shape and Performance of Beef Bulls. I. Principal Components as Measures of Size and Shape in Young Hereford and Angus Bulls

Cited by 49 publications

References 0 publications

Factor analysis for genetic evaluation of linear type traits in dual-purpose autochthonous breeds

Factor analysis for genetic evaluation of linear type traits in dual-purpose autochthonous breeds

Charaterisation of Zulu (Nguni) sheep using linear body measurements and some environmental factors affecting these measurements

An Analysis of the Dependency Structure between a Gilt's Prebreeding and Reproductive Traits. II. Principal Component Analysis

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