Growth rate, slaughter traits and meat quality as related to backfat

Animal Science Papers and Reports vol. 24 (2006) Supplement 1, 51-55
Institute of Genetics and Animal Breeding, Jastrzębiec, Poland
Presented at the Conference
“Genetic and Breeding Research on Pigs
with Special Reference to Indigenous Breeds”
organized to commemorate the 10th anniversary
of the death of Professor Stefan Alexandrowicz
20-21 October 2005, Poznań, Poland
Growth rate, slaughter traits and meat quality as related
to backfat thickness in Polish Large White gilts
Grażyna Michalska, Jerzy Nowachowicz,
Przemysław Dariusz Wasilewski, Tomasz Bucek
Department of Animal Products Evaluation, University of Technology and Agriculture,
Kordeckiego 20, 85-225 Bydgoszcz, Poland
The research concerned 40 Polish Large White gilts kept under standardized conditions and
slaughtered on day 185 of life. Based on average backfat thickness from 5 measurements animals
were divided into two groups of 20, i.e. with “thin backfat” and “thick backfat” - up to 3.02 cm
and above 3.03 cm, respectively. A detailed dissection of primary cuts was carried out according to
the Polish Pig Testing Station (SKURTCh). The significance of differences between the groups was
evaluated with Student t-test. The gilts with “thin backfat” used significantly less feed per kg body
weight gain and showed higher meat weight in primary cuts (except shoulder), higher psoas weight
and lower fat weight in butt and loin as well as lower leaf fat weight than “thick backfat” gilts.
KEY WORDS: backfat / carcass / gilts / growth rate / meat / slaughter traits
A number of published animal production scientific papers dealt with meat
content of carcass and results of other performance traits of pigs. Not many papers
regarded the influence of fat content of carcass on commercially important traits,
including growth rate and slaughter quality indicators referring to meat quality. Longterm intensive genetic improvement of pigs caused increase in daily live weight gain
51
G. Michalska et al.
leading to increase in body protein deposition and eventually to increase in meat
content and decrease in fat content of carcass [Fandrejewski 1992, Cameron and
Currant 1995]. Some research showed negative genetic correlation between quantity
and quality of meat in carcass [Malmfors et al. 1980, Steane 1981]. Polish Large
White pigs exhibit good growth rate and slaughter performance [Różycki and Tyra
2003]. Breeding research tends to improve their meat content and decrease fat content
of carcass [Różycki 1994].
The aim of this paper was to analyse the growth rate and slaughter traits including
quality of meat in Polish Large White gilts as referred to backfat thickness.
Material and methods
The research concerned 40 Polish Large White (PLW) gilts kept during control
growth period under standardized conditions and slaughtered on day 185 of life.
Depending on mean backfat thickness from 5 measurements (over the shoulder, on
back, and on I, II, III loin) animals were divided into two groups of 20 , i.e. of “thin
backfat” – up to 3.02 cm, and “thick backfat” – above 3.03 cm.
Detailed dissection of primary cuts and evaluation of selected meat quality traits
(pH1, colour, soluble protein content) were carried out according to methodology
applied in Polish Pig Testing Stations (SKURTCh) as described by Różycki [1996].
The significance of differences between tested groups was evaluated using
Student t-test [Ruszczyc 1981]. Calculations were made with computer programme
Statistica PL [2000].
Results and discussion
In Table 1 presented are means for growth rate, slaughter traits and some parametres
of meat quality in PLW gilts. The intergroup difference between means for backfat
thickness from 5 measurements was 0.52 cm (P≤0.01). Growth rate of gilts with “thin
backfat” was higher by 30 g/day from that in “thick backfat” gilts (not confirmed
statistically). Gilts of “thin backfat” group showed lower (P≤0.05) feed intake per
1 kg body weight gain than those of “thick backfat” layer. In earlier authors’ study
[Michalska et al. 2004] concerning Belgian Landrace pigs no significant differences
were identified in slaughter traits between the “thin backfat” and “thick backfat”
animals.
Body weight at slaughter (at the age of 185 days) was by 4 kg higher in “thin
backfat” than in the “thick bacfat” gilts (P≤0.05). Dressing percentage was higher by
1.23 per cent units in gilts with “thick backfat” (P≤0.05)
The weight of meat from primary cuts (except shoulder) and weight of psoas
in gilts from “thin backfat” group were both higher from those obtained by gilts of
“thick backfat”. The difference in total weight of meat from primary cuts between
groups was 1.49 kg (P≤0.01). Significantly higher weight of butt fat and psoas fat and
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Genetic and Breeding Research on Pigs with Special Reference to Indigenous Breeds
Table 1. Means for growth and slaughter and traits in Polish Large White pigs
Trait
Mean backfat thickness from 5 measurements (cm)
Daily live weight gain (g)
Feed intake per kg live weight gain (kg)
Body weight at slaughter (kg)
Cold right half-carcass (kg)
Dressing percentage
Meat weight (kg)
butt
shoulder
proper ham
shank
loin
belly
ribs
Total meat weight in primary cuts (kg)
Fat weight (kg)
butt
shoulder
proper ham
shank
loin
belly
ribs
Total fat weight in primary cuts (kg)
Psoas weight (kg)
Leaf fat weight (kg)
pH1
Color brightness (%)
Soluble protein (%)
Backfat thickness from 5
measurements
up to 3.02 cm
above 3.03 cm
2.74A±0.24
712±58
2.95a±0.24
99.00a±6.58
38.62±2.51
78.28a±1.81
3.26B±0.22
683±33
3.08b±0.16
95.00b±3.74
37.69±1.77
79.60b±1.83
2.92A±0.22
2.80±0.48
5.15A±0.59
0.81a±0.11
4.57a±0.41
2.32a±0.34
0.65a±0.07
19.16A±1.89
2.68B±0.26
2.57±0.28
4.70B±0.44
0.74b±0.07
4.29b±0.39
2.09b±0.27
0.60b±0.08
17.67B±1.42
1.48A±0.18
1.08±0.15
1.78±0.25
0.37±0.05
2.40A±0.32
1.97±0.32
0.07±0.02
9.11±1.02
0.26a±0.04
0.80A±0.15
6.14±0.17
25.48±3.22
7.89±0.36
1.69B±0.21
1.17±0.12
1.92±0.22
0.38±0.04
2.86B±0.32
2.11±0.29
0.07±0.02
9.73±2.06
0.24b±0.03
0.93B±0.11
6.09±0.30
26.68±3.78
7.93±0.47
aA...
Wihin rows means bearing different letters differ significantly at: small letters - P≤0.05;
capitals - P≤0.01.
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G. Michalska et al.
higher leaf fat weight in gilts characterized by “thick backfat” were shown compared
to gilts from the other group. In the earlier study [Michalska et al. 2004] carried out
on animals of Belgian Landrace significant differences were identified in weight of
loin fat and butt fat and in total fat weight of primary cuts, and also in leaf fat weight
between carcasses of pigs of thin and thick backfat. Litwińczuk et al. [2003] stated that
carcasses of fatteners from mass-keeping in Middle-East Poland which contained less
fat, showed more favourable parametres of slaughter value and better meat quality.
No significant differences between groups of backfat thickness were identified
within meat quality parametres. The results concerning meat colour of tested pigs
should be considered as satisfactory and regarding the criteria given by Kortz [2001]
testify to normal meat. However, pH1 values ranged from 5.9 to 6.2 and thus qualified
the meat as partially PSE. In other papers pH1 values of meat of PLW pigs were reported
to be higher than showed in the current paper [Fandrejewska 1997, Nowachowicz et
al. 2000, Różycki and Tyra 2003]
Summarizing it should be stated, that gilts with “thin backfat” showed significantly
more favourable feed conversion, higher meat weight in primary cuts (except
shoulder), higher psoas weight and also lower fat weight in butt and loin and lower
leaf fat weight than gilts characterized by “thick backfat”.
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Grażyna Michalska, Jerzy Nowachowicz,
Przemysław Dariusz Wasilewski, Tomasz Bucek
Wyniki w zakresie cech tucznych i rzeźnych z uwzględnieniem
jakości mięsa świń rasy wielkiej białej polskiej o zróżnicowanej
grubości słoniny
Streszczenie
Badania dotyczyły 40 loszek rasy wielkiej białej polskiej utrzymywanych w ujednoliconych
warunkach i ubijanych w wieku 185 dni. W zależności od średniej grubości słoniny z 5 pomiarów
zwierzęta podzielono na 2 grupy (po 20 loszek), tj. o „cienkiej słoninie” - do 3,02 cm i „grubej
słoninie” - powyżej 3,03 cm. Szczegółową dysekcję wyrębów podstawowych przeprowadzono zgodnie
z metodyką stosowaną w SKURTCh. Istotność różnic między grupami określono na podstawie testu
t-Studenta. Loszki o „cienkiej słoninie” charakteryzowały się istotnie mniejszym zużyciem paszy na
przyrost 1 kg masy ciała i większą masą mięsa w wyrębach podstawowych (z wyjątkiem łopatki) oraz
większą masą polędwiczki, a także mniejszą masą tłuszczu w karkówce i polędwicy oraz mniejszą masą
sadła w porównaniu ze zwierzętami z „grubą słoniną”.
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