El grado de conformación de los terneros no predice el desempeño en el matadero terneros de cruce industrial

Introduction

The implementation of sexed and beef
breeding strategies in the dairy industry has significantly increased the number
and proportion of beef-on-dairy animals in the beef supply-chain. In the UK for
example, around 45% of beef originates from the dairy herd.

These animals aren’t generally bred for a specific
market. The beef industry acquires these animals at a young age, either at
public livestock auctions (McHugh et al., 2010; Dunne et al., 2021) or through
local “calf dealers” that split the animals between different feedlots. The price
of these calves is determined by many factors including the purchasers (Berry
et al., 2021), seasonal effects, or visual assessment (Marquou et
al., 2019
Wilson et al., 2020).

This study calculates preliminary correlations
between one beef-on-dairy calf payment grading scheme and a range of terminal
traits, as well as estimated birth weight.

Materials and methods

The data consisted of 2,782 British Blue X
dairy animals owned by a UK livestock trading company. Calves aged between 9
and 75 days were weighed and graded based on health and conformation by trained
staff at purchase. The company’s categorical grading scale was transformed into
a numerical scale for analysis. Numeric grade descriptions are as follows;

4:

Well defined confirmation from shoulder through to a
full hindquarter, strong fleshing across the loin and back. Must be above
average weight for age

3:

A well-conditioned calf, with good loin development
and rump confirmation. Calves look full, alert and coat shines. Weight for
age parameters are met

2.5:

Intermediate category between grades 3 and 2 (calf graders have
recorded both grades to the animal on entry to the facility)

2:

Healthy calf in good condition, with fat coverage
over the ribs and back but without the fullness of grade 3. Shape over the
hindquarter is displayed but requires development through time, feeding and
rear

1:

Condition is below average. The loin and belly may look concave with a
plainer hindquarter, particularly down the leg. Overall skeletal structure
may be smaller, with less fleshing throughout – ribs and spine may be
visible, with a dull coat. Requires intensive attention to detail in rear to
ensure growth and health throughout life

0:

Out of specification calf which may appear dull and
empty due to lack of fat and flesh. Topside and rump appear concave, and the
calf may not be fully alert.

Also awarded for calves with eye infections,
ruptures, ringworm, diphtheria, high temperature or signs of other
pathogens/parasites.

All animals were reared in the same facilities,
under the same diet and conditions. After slaughter, terminal records (carcass
weight, EUROP grade, slaughter age) were collected for each animal, along with
data on carcass value and overall profit.

Birth weight was estimated as current
weight – (age in days*0.7), assuming calves grow 0.7 kg/day in the first month,
which is consistent with previous internal analysis (M Smith, personal
communication).

Phenotypic correlations were calculated between
numerical calf grade and; estimated birth weight, carcass weight, conformation,
fat, carcass value and profit, using R Statistical Software (v4.2.0; R Core
Team 2022). Records were not available for all animals for every trait of
interest.

Results

Table 1: Phenotypic correlations between numerical calf grade and 6
terminal traits, as well as estimated birth weight.

Trait

Correlation

No. records

Estimated birth weight

0.39

2730

Carcass weight

0.09

1641

EUROP Conformation
score

0.00

1639

EUROP Fat score

0.14

1626

Slaughter age

-0.01

1641

Carcass value

0.10

1619

Profit

0.06

1474

Calf grade is moderately correlated with
estimated birth weight (0.39), and weakly correlated with carcass traits (0.00
to 0.14) and profit (0.06).

Discussion

There is a strong industry belief that
visual calf quality assessment is predictive of an animal’s performance at
slaughter. Dairy farmers are keen to produce high quality calves, as they tend
to fetch higher prices at auction. However, these subjective assessments vary
significantly depending on the person carrying out the assessment, and even
experienced calf graders can struggle to commit to a specific grade (see grade
2.5).

Results from this preliminary analysis demonstrate
little relationship between calf quality in early life, and performance at
slaughter. This is a preliminary study on one UK-specific dataset; however,
terminal traits are complex in nature, with both genetic and non-genetic
effects influencing the phenotype. (Pritchard et al. 2021, Berry et al. 2022), and
so these results are not surprising.

Rather than relying on visual assessment, the
authors recommend assessment of an animal’s genetic potential for growth via
individual breeding values or a terminal genetic index.

Conclusions

Low correlations between calf grade and
terminal traits suggest this specific calf grading scheme cannot accurately
predict terminal performance in this population. Further analyses should be
conducted with wider datasets to validate these findings. 

  • vetoquinol
  • analítica veterinaria
  • delaval
  • innogando
  • Secure Cattle
  • hifarmax
  • DML Datamars Livestock
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