Slaughter value and quality of meat from Pomeranian lambs and crossbreds by Blackface and Charolaise rams
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Animal Science Papers and Reports vol. 24 (2006) Supplement 2, 53-60
Institute of Genetics and Animal Breeding, Jastrzębiec, Poland
Presented at the III Conference
“Genetic and environmental possibilities
of adjusting the slaughter value and meat quality
of animals to consumers’ requirements”
7-8 September 2006, Lublin-Krasnobród, Poland
Slaughter value and quality of meat from Pomeranian
lambs and crossbreds by Blackface and Charolaise rams
Henryk Brzostowski, Janina Sowińska, Zenon Tański
Faculty of Animal Bioengineering, University of Warmia and Mazury in Olsztyn,
Oczapowskiego 5, 10-718 Olsztyn, Poland
Selected indicators were compared of the slaughter value and quality of meat in 50-day-old pure
Pomeranian lambs (P) and F1 lambs (P ewe x Blackface ram and P eve × Charolaise ram - PB and PCh
crossbreds, respectively). The slaughter value was determined based on live body weight, intestinal
fat weight, dressing percentage, loin eye length and area, thickness of fat cover over the ribs and
loin, proportions of valuable cuts in a carcass, and tissue composition of the leg. Meat quality was
evaluated based on the chemical composition as well as the physico-chemical and sensory properties
of quadriceps femoris muscle. PB and PCh lambs, as compared with P lambs, had higher live weight, a
higher dressing percentage, a higher proportion of valuable cuts in a carcass, as well as more desirable
lean-to-bone and lean-to-fat ratios in the leg. The length and area of loin eye were also greater in PCh
lambs. Meat from PCh lambs, as compared to meat from lambs P, contained more protein and less
collagen, and was characterized by a better water holding capacity, a lighter color, a greater diameter
of muscle fibers, as well as worse tenderness and juiciness. Meat from PB lambs showed a lower
collagen content and a smaller diametre of muscle fibers than meat from P lambs, as well as a higher
fat content, better tenderness and juiciness than meat from PCh lambs.
KEY WORDS: cholesterol / collagen / crossing / lambs / meat / slaughter value
53Henryk Brzostowski et al.
The principles of human nutrition change along with the progress of civilization. It
follows that food products of animal origin, including lamb meat, have to meet higher
and higher expectations. A high protein content accompanied by a low fat content, as
well as the optimum fatty acid profile and good flavor characteristics, fulfilling the
requirements of modern dietetics and prophylactic treatment, decide about consumer
acceptance and interest in a given product [Hoffman et al. 2003, Kłobukowski et al.
2003]. Milk-fattened lambs (12-30 kg live weight) characterized by high meat content
of carcasss, low fatness and health-promoting properties of meat, can satisfy these
requirements [Borys et al. 2003, Brzostowski et al. 2004].
Taking into account the present breed structure of the sheep population in Poland,
it seems that lamb meat quality can be improved through commercial crossing of
ewes of regional breeds, perfectly adjusted to local environmental conditions, with
rams of meat breeds. The results of such crossing are greatly affected by the proper
choice of breed components [Pieniak-Lendzion et al. 1998, Brzostowski et al. 1999,
Ciuryk i Kaczor 2001]. In the Pomeranian region an important role may be played in
this respect by early-maturing Pomeranian ewes used for wool and meat production.
Professional literature on the subject provides no information on the crossing ability
of Pomeranian ewes with rams of mutton breeds, directed primarily towards the
production of light slaughter lambs. Facing the above, the aim of this study was to
determine the slaughter value and quality of meat from 50-day-old Pomeranian (P)
ewes and F1 crossbreeds of P ewes with Charolaise and Blackface rams.
Material and methods
The investigation was performed on three groups of 50-day-old ram lambs. Group
1 were 12 pure Pomeranian lambs (P), group 2 were 12 F1 PB lambs coming from
crossing of P ewes with Blackface rams (B) and group 3 were 12 F1 PCh lambs from
crossing of P ewes with Charolaise rams. Apart from mother’s milk, the lambs of
all groups were offered mixed feed composed of meadow hay, maize silage and CJ
concentrate, in accordance with lamb nutrient requirements [Ryś 1998].
The slaughter value was determined with the method recommended by the
National Research Institute of Animal Production [Nawara et al. 1963], based on
live body weight, intestinal fat weight, dressing percentage, loin eye length and area,
thickness of fat cover over the last rib and loin, proportions of valuable cuts in a
carcass and tissue composition of the leg.
Meat quality was assessed based on the chemical composition as well as on the
physico-chemical and sensory properties of quadriceps femoris muscle. The following
determinations were made: dry matter – by sample drying at 105oC, crude protein
– by the Kjeldahl method, crude fat – by the Soxhlet method, crude ash – by sample
ashing at 550oC, gross energy – with a KL 10 adiabatic bomb calorimeter, water
holding capacity – by the Grau and Hamm method [1953], color lightness – with a
Specol spectrocolorimeter with an R 045 remission attachment at a wavelength of
54Adjusting the slaughter value and meat quality of animals to consumers’ requirements
560 nm, pH – 24 hours post mortem with a Radiometr PHM 22 pH-meter, cholesterol
– with the method proposed by Komprda et al. [2000] with an EPOLL 20 colorimeter,
collagen – based on the amount of hydroxyproline [Blomfield and Farrar 1964]. Meat
samples were hydrolyzed as described by Dzierżyńska-Cybulko and Kijowski [1982],
following the removal of the outer collagen membrane (epimysium) containing less
hydroxyproline and having a slightly different amino acid composition. Muscle
fibre thickness was measured on samples of longissimus lumborum muscle taken
immediately after slaughter, fixed in neutralized (pH 7.4) 10% formalin and paraffin-
embedded. Microtome sections were hematoxylin- and eosin-stained. Thickness
measurements were performed by computer image analysis, using LUCIA 3.52a
software.
Sensory evaluation of meat was preceded by thermal treatment, as described
by Baryłko-Pikielna [1975]. A five-point scale was applied, taking into account the
following quality attributes of cooked meat: aroma (intensity and desirability), taste
(intensity and desirability), tenderness and juiciness.
The results were verified statistically by the analysis of variance in a one-factor
orthogonal design, using STATISTICA 7 software.
Results and discussion
Rams of meat breeds mated to Pomeranian ewes had a positive effect on the
live body weight and some carcass quality indicators in F1 crossbred lambs (Tab. 1).
Lambs by Blackface and Charolaise sires (PB and PCh crossbreds, respectively) had
a significantly higher dressing percentage (48.21% and 48.16%, respectively) than
purebred P lambs (46.83%). The proportion of valuable cuts was highly significantly
lower (40.76%) in P lambs, as compared to PB (42.45%) and PCh (42.73%) lambs.
These differences resulted primarily from significantly lower leg weight in the
carcasses of P lambs.
The leg tissue composition was also less desirable in P lambs. In comparison with
the legs of PB and PCh lambs, the legs of P lambs contained by 2.39 and 2.09 per
cent points (pp) less lean (P≤0.01) and by 1.29 and 1.15 pp more bones. As a result,
the values of the lean-to-bone and lean-to-fat ratios were also lower (P≤0.05). The
length and area of loin eye were also greater in PCh lambs than in P lambs. Borys et
al. [2003] also demonstrated that the genotype affected the leg tissue composition and
loin eye area in lambs.
The above results show that both slaughter value and carcass quality of Pomeranian
ewes, although satisfactory, can be substantially improved through crossing with
properly selected rams of meat breeds. Also Lipecka et al. [2001] found that lambs
with Charolaise genes had higher live weights and muscular tissue content than
lowland lambs. The beneficial influence of Blackface sires on the slaughter quality of
crossbred lambs was confirmed also by Brzostowski et al. [2001].
55Henryk Brzostowski et al.
Table 1. Live body weight at slaughter and carcass quality indicators in lambs
Lamb group
Trait Pomeranian × Pomeranian ×
Pomeranian
Blackface Charolaise
mean V(%) mean V(%) mean V(%)
Slaughter weight (kg) 17.89b 9.25 18.69a 8.34 18.60a 16.05
Intestinal fat (%) 1.45 27.62 1.34 23.79 1.45 25.38
Dressing percentage 46.83b 2.55 48.21a 3.48 48.16a 3.14
Loin length (cm) 21.93b 12.39 23.25 6.39 24.22a 8.49
Loin eye area (cm2) 10.78b 16.69 11.28 6.94 11.58a 7.14
Fat over the loin (mm) 0.92 60.80 0.99 37.76 0.97 70.05
Fat over the ribs (mm) 2.83 57.96 3.29a 68.07 2.53b 93.53
Valuable cuts (%) 40.76B 1.84 42.45A 2.55 42.73A 3.97
Leg weight (kg) 1.14b 12.25 1.25a 9.01 1.25a 17.60
Leg composition
lean (kg) 0.80 12.48 0.91 9.73 0.91 18.23
lean (%) 70.27B 2.93 72.63A 1.90 72.36A 2.02
fat (kg) 0.14 20.93 0.13 14.65 0.14 19.95
fat (%) 11.87 14.46 10.72 14.40 10.85 13.41
bone (kg) 0.20 13.61 0.21 10.44 0.21 17.20
bone (%) 17.94 8.84 16.65 5.52 16.79 5.17
Lean to bone ratio 3.95b 11.07 4.37a 5.99 4.32a 5.89
Lean to fat ratio 6.03b 14.60 6.93a 17.22 6.79a 15.10
aA...
Means within rows bearing different superscripts differ significantly at: small letters −
P≤0.05; capitals − P≤0.01.
Sire breed had a significant effect on some chemical and physico-chemical
properties of meat (Tab. 2). Meat from PCh crossbred lambs, contained more protein
and less fat and collagen (P≤0.05), and was characterized by a better water holding
capacity (P≤0.05), a lighter color (P≤0.01), and a greater diameter of muscle fibres
(P≤0.01) than P lambs meat. A significantly better W/P ratio, indicating better ripeness
of meat from PCh lambs, results from a higher content of protein and a lower content
of water. This confirms the opinion that protein is the main water-biding component,
which was reflected by the best water holding capacity of meat from PCh lambs. A
higher protein concentration in meat from crossbreds was also observed by Hoffman
et al. [2003]. Meat from PB lambs contained less collagen, showed a lighter color
(P≤0.05), a smaller diameter of muscle fibres and a higher fat content than meat
from PCh lambs. The lamb genotype had no effect on cholesterol level of meat. As
56Adjusting the slaughter value and meat quality of animals to consumers’ requirements
Table 2. Chemical composition and physico-chemical properties of meat in lambs
Lamb group
Trait Pomeranian × Pomeranian ×
Pomeranian
Blackface Charolaise
mean V(%) mean V(%) mean V(%)
Dry matter (%) 21.22 4.28 21.87 3.35 22.12 2.68
Crude protein (%) 18.12b 4.42 18.38 3.30 18.78a 3.27
Fat (%) 1.59 28.41 1.72a 15.26 1.48b 34.75
Ash (%) 1.11 2.80 1.15 3.61 1.15 4.48
Ratio W/P (Water/Protein) 4.36A 5.29 4.25 4.80 4.15B 3.25
pH24 6.53 2.86 6.54 3.48 6.50 3.94
GE/100g 106.21 5.19 110.38 4.32 107.18 7.26
Colour 22.50Aa 16.90 19.73b 9.93 19.04B 9.40
Water holding capacity (cm2) 9.55a 8.13 8.51 23.86 7.40b 27.81
Cholesterol (mg/100 g) 52.43 6.87 54.35 12.89 54.84 7.62
Collagen (mg/100 g) 236.57A 7.78 182.34Bb 13.42 213.55a 8.12
Muscle fibre thickness (µm) 21.25b 13.40 20.26B 8.43 23.15Aa 5.88
aA...
Means within rows bearing different superscripts differ significantly at: small letters − P≤0.05;
capitals − P≤0.01.
compared to meat from lambs aged 70 and 90 days, in a study conducted by Borys
et al. [2003], the cholesterol content of meat from the lambs described in the present
report can be considered low (P – 52.43, PB – 54.35, PCh – 54.84 mg/100 g).
A sensory evaluation, including aroma, consistency (tenderness, juiciness)
and palatability (Tab. 3), revealed that the genotype had a considerable effect on
some quality characteristics of cooked lamb meat. Meat from PB lambs received
the highest scores for tenderness (4.59 points) and juiciness (4.59 points), and that
from PCh lambs – the lowest (4.37 and 4.29 points respectively), P≤0.05. It seems
that a significantly higher intramuscular fat content was responsible for the fact that
meat from PB lambs got higher scores for the above quality attributes. According
to Dankowski and Zielińska [8], intramuscular fat contributes to loosening of the
muscular tissue microstructure, thus improving tenderness, juiciness and other sensory
properties of lamb meat. A higher collagen content and a greater diameter of muscle
fibres also deteriorated the tenderness and juiciness of meat from PCh lambs. Thinner
muscle fibres, containing less collagen (the main component of connective tissue) are
easier and faster digested by proteolytic enzymes in the stomach, and better utilized
by humans [Oprządek and Oprządek 2000, Kłobukowski et al. 2003]. Due to a high
protein content, low levels of cholesterol and collagen, as well as low calorific value,
57Henryk Brzostowski et al.
Table 3. Sensory evaluation of lamb meat (points)
Lamb group
Trait Pomeranian × Pomeranian ×
Pomeranian
Blackface Charolaise
mean V(%) mean V(%) mean V(%)
Aroma − intensity 5.00 0.00 5.00 0.00 5.00 0.00
Aroma − desirability 5.00 0.00 5.00 0.00 5.00 0.00
Tenderness 4.54 17.22 4.59 10.19 4.37b 9.16
Juiciness 4.42 13.51 4.59a 10.19 4.29b 7.69
Taste − intensity 4.83 6.74 4.83 0.00 4.83 0.00
Taste − desirability 4.71 9.56 4.83 0.00 4.83 0.00
Overall evaluation 4.75 5.03 4.81 3.83 4.72 6.62
ab
Means within rows bearing different superscripts differ significantly at P≤0.05.
meat from lambs of all genotypes analyzed in the present study can be recommended
as a valuable component of a well-balanced healthy diet.
Higher live body weight, a higher dressing percentage, a higher proportion of
valuable cuts in a carcass, better meat content of carcass, a higher protein content
and a lower collagen content, as well as a better water holding capacity and a lighter
colour of meat, recorded in crossbred lambs indicate that Pomeranian ewes should be
mated to Blackface, and especially to Charolaise rams.
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59Henryk Brzostowski et al.
Henryk Brzostowski, Janina Sowińska, Zenon Tański
Wartość rzeźna i jakość mięsa jagniąt rasy pomorskiej i jagniąt
mieszańców owcy pomorskiej z czarnogłówką i owcą rasy charolaise
St r e s z c z e n i e
Oceniano wybrane wskaźniki wartości rzeźnej i jakości mięsa 50. dniowych jagniąt owcy pomorskiej
(P) i jej mieszańców po trykach rasy czarnogłówka (PB) i charolaise (PCh). W ocenie wartości rzeźnej
uwzględniono: masę ciała przed ubojem, masę łoju okołojelitowego, wydajność rzeźną, długość i
powierzchnię oka polędwicy, grubość tłuszczu nad żebrami i nad polędwicą, udział wartościowych
wyrębów w tuszy oraz skład tkankowy udźcca. W ocenie jakości mięsa przeprowadzonej na mięśniu
czterogłowym uda (m. quadriceps femoris) przeanalizowano skład chemiczny oraz właściwości
fizykochemiczne i sensoryczne mięsa. Jagnięta PB i PCh charakteryzowały się wyższą niż jagnięta P
masą ciała przed ubojem i wydajnością rzeźną, wyższym udziałem wartościowych wyrębów w tuszach,
korzystniejszym stosunkiem mięsa do kości i mięsa do tłuszczu w udźcach, a jagnięta PCh także dłuższą i
o większej powierzchni oka polędwicą. Mięso jagniąt PCh w stosunku do mięsa jagniąt P zawierało więcej
białka, mniej kolagenu oraz charakteryzowało się lepszą wodochłonnością, jaśniejszą barwą, mniejszą
średnicą włókien mięśniowych oraz gorszą kruchością i soczystością. Mięso jagniąt PB odznaczało się
niższą zawartością kolagenu i mniejszą średnicą włókien mięśniowych niż mięso jagniąt P oraz wyższą
zwartością tłuszczu, lepszą kruchością i soczystością niż mięso jagniąt PCh.
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