joseph stock - objective feet & leg structure between selection & second gestation &...

IOWA STATE UNIVERSITYDepartment of Animal Science

Objective feet and leg joint structure between selection and second gestation and gestation ages

J.D. Stock1, J.A. Calderón Díaz1,2, B.E. Mote3,4, K.J. Stalder1

1Department of Animal Science, Iowa State University, Ames, IA 500112Department of Animal Behaviour and Welfare, Institute of Genetics and

Animal Breeding, Polish Academy of Sciences, ul. Postepu 36A, Jastrzębiec, 05-552 Magdalenka, Poland 3Fast Genetics, Saskatoon, SK, S7L 7E1

4University of Nebraska – Lincoln, Lincoln, NE 68588


General Introduction

Studies have reported that feet and leg problems are the second leading reason for culling among sows with up to 20.3% of removals due to leg problems (Dagorn and Aumaitre, 1979; Stein et al., 1990; Cederberg and Jonsson, 1996; Sehested and Schjerve, 1996; Boyle et al., 1998; Anil et al., 2005; Mote et al., 2009)

This is likely an underestimate as feet and leg problems affect other traits that could be used as reason for removal


General Introduction

Selection for optimal feet and leg conformation traits improves sow longevity

Visual appraisal methods that rely on trained individuals to score an animal on a categorical scale have been previously developed Multiple systems that are similar, but different

Vulnerable to varying degrees of bias and error associated with the ability of the scorer (Main et al., 2000; Van Nuffel et al., 2009; D’Eath, 2012)


NSIF Structural Scoring Guide

NSIF 2002-2003

Takes experience to differentiate between two individual scores.


Introduction

Final selection of breeding females occurs at roughly 20 weeks of age (140 days) Still undergoing rapid growth during this age

Life events, such as gestation, which adds significant weight, have not been able to be evaluated for potential effects on structure

Female replacements do not reach their mature physical size until after their second parity (Robison, 1976)

Consequently, most females are removed for feet and leg problems during the time period between selection and second parity (Mote et al., 2009)


Introduction

Few studies have examined structural change over time in swine

Fernàndez de Sevilla et al. (2009) observed six feet and leg conformation traits between time at selection and their second parity Sickle hocked rear legs became more prevalent with age

Pasterns became straighter between selection and first parity

No studies were found to have examined structural change during gestation


Objectives

Evaluate feet and leg joint angle measurements between time of selection and after their first parity

Evaluate feet and leg joint angle measurements across gestation days


Materials and Methods

319 maternal gilts at selectionAge at measurement ranged from 19 to 25 weeks old

277 remained post 1st parityGestation days ranged from zero to 87Average gestation 26.7 ± 17.2 days


Animals by Analysis

Parity 0 – Parity 1Females with repeated records from selection and post

1st parity were used (126 total females)Only females in their first 21 days of gestation post 1st

parity were included

Parity 2 farm and gestation ageAll 277 females post 1st parity are included


Material and Methods

ImageJ software was used to take feet and leg measurements from the images

Phenotypic traits (angles) are measured in degreesKneeFront and rear pasternHockRear stance


Profile diagram of joint angles measured

a & b – knee; c & d – front pastern; e & f – hock; g & h – rear pastern


Rear stance diagram angles measured

a & b – rear stance


Parity 0 – Parity 1 Analysis

Proc Mixed from SAS® software was used

Fixed effectsParity, side of measurement

ID was used as a random effect

Parity was used as a repeated variable

Results Fixed effects = LS means ± SE


Parity 2 Farm and Gestation Age Analysis

Proc Mixed from SAS® software was used

Fixed effectsFarm, side of measurement

Linear covariateGestation Age (days)

ID was used as a random effect

Results Fixed effects = LS means ± SELinear covariate = Reg ± SE


Difference between selection and 1st parity

1 Parity is repeated from selection (0) to first parity (1) for 126 females2 Side is measured from the left and right profile images for the knee, front and rear pastern and the

hock, rear stance does not have a side variablea,b Values in a column without common superscript are significantly different (P < 0.05)

Knee Front Pastern

Rear Pastern Hock Rear Stance

VariableLS

Means SE LS Means SE LS


Means SE

Parity1

0 160.2a 0.2 57.0a 0.5 58.5a 0.5 140.5a 0.4 91.4a 0.6

1 159.4b 0.2 56.1a 0.5 53.3b 0.5 146.4b 0.4 86.5b 0.6

Side2

L 160.0a 0.2 56.9a 0.5 56.0a 0.5 142.8a 0.4NA

R 159.5a 0.2 56.2a 0.5 55.8a 0.5 144.1b 0.4


Farm and gestation differences second gestation

1 Sows were distributed across three farms, farm A (82), farm B (98), and farm C (97)2 Side is measured from the left and right profile images for the knee, front and rear pastern and the

hock, rear stance does not have a side variablea,b Values in a column without common superscript are significantly different (P < 0.05)

Knee Front Pastern Rear Pastern Hock Rear Stance

VariableLS



Means SE

Farm1

A 159.0a,b 0.3 55.6a 0.6 51.4a 0.6 146.4a 0.5 82.5a 0.7B 158.5a 0.3 58.2b 0.6 54.5b 0.6 147.4a 0.5 88.4b 0.7C 159.5b 0.3 57.5b 0.6 55.8b 0.6 147.6a 0.5 88.5b 0.7

Side2

L 159.4a 0.2 57.9a 0.4 54.5a 0.4 147.8a 0.3 NAR 158.6b 0.2 56.3b 0.4 53.3b 0.4 147.5a 0.3 NA

Gestation Age3 -0.02 ± 0.01* 0.04 ± 0.02* 0.02 ± 0.02 0.05 ± 0.02* -0.01 ± 0.02


DiscussionRear pastern angles decreased

(weakened) and hock angles increased (straightened) between selection and 1st

parity

Rear stance also decreased between selection and first parity May be due mostly to farm difference in second analysis

Side was only significant for the hock, however difference is small


Discussion

Farm differences were found in the knee, front and rear pasterns and to the highest degree in the rear stance between farms A and B,CCould account for parity difference in rear stance

Side was significant for the knee, and front and rear pastensAngle difference are small and are still most likely not

biologically important


Discussion

Gestation age showed significance in the knee, front pastern and hock anglesKnee angle values decreased over gestation daysFront pastern angle values increased over gestation

days


ConclusionsAs age increases structure changes, with rear

leg joints showing greater variation than the front leg

Front leg differences across age are generally small

Results suggest that environmental factors, such as farm, can contribute to angle differences

Small angle changes over time could indicate structure that carries over the life of the female


ConclusionsRear leg structure still requires further

investigation

Fernàndez de Sevilla et al. (2009) stated, “The detection of genetic components in leg conformation and specific leg defects in sows should prompt further research into the genetic architecture of morphological traits in sows.” The results of our study were in direct contradiction to the

results found in that study and further validates the need to look further into genetic aspects of structure change over time


Ongoing and Future Work

Gestation structural changes are being examined in more detail within an individual

Evaluation within an individual will carry over for three parities and include pedigree information for genetic analysis


AcknowledgmentsFast Genetics

Farm Employees


QuestionsThank you for your time and attention!

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