FR2690314A1 - Process for treating animals to improve the quality of meat. - Google Patents

Abstract

Method for the treatment of suidae, particularly pigs in order to improve the quality of the meat, and particularly its water retention capacity, by incorporating glycerol, one of its precursors or one of its metabolites. The pigs are treated by adding to the food approximately 5 % glycerol at the end of the growth period, i.e. is to say just before slaughtering.

Description

 The present invention relates to a process for treating animals with a view to improving the quality of their meat and in particular its water retention power.

 Water is a fundamental constituent of living beings in which it represents 60 to 70% of the body weight.

The water necessary for the daily need of the organism is provided both by drinking water and by the water contained in food. This water is distributed between intra-cellular compartments and extracellular compartments
As the animals grow, there is an increase in the body's fat content and a correlated decrease in the water content.

The total water of the muscle (approximately 75% of the weight of the muscle) is divided into two fractions: bound water and free water which represent respectively 5 to 10% and 90 to 95% of the total water
Bound water is strongly attached to muscle proteins as water of hydration. Free water is associated with dissolved substances and is immobilized in extra-cellular spaces, or retained by myofibrils or the sarcoplasmic reticulum. It is therefore bound water which intervenes in the water retention capacity of meat. This power is linked to the structure and physico-chemical characteristics of muscle proteins. It is also dependent on the species of the animal, its breed, its sex, its age and the characteristics of each of the muscles.
In pigs in particular, we meet animals whose muscles have a low water retention capacity. These so-called "PSE" meats (pale, soft and exudative), "(myopathic, exudative and depigmentary) or even" pissing meats "are subject to significant commercial depreciation due to their poor ability to manufacture delicatessen products.
To overcome this low retention power, glycerol has been introduced in particular in cold meats such as sausages. Glycerol is then added at the time of manufacture.
However, little attention has been paid to the introduction into the diet of factors making it possible to increase water retention, food being considered in the prior art to play a minor role in this retention.

Glycerol has already been used in the prior art to increase the level of sugars in the blood of ruminants, as well as to increase their milk production. The patent
US 4,127,676 relates to such a method in which ruminants are administered from 40 to 500 g per day of polyol carrying alcohol functions such as glycerol.

 This patent only mentions an effect of glycerol treatment on the metabolism of sugars as well as on the production of fatty acids. However, it does not mention any effect on the quality of animal meat.

I1 therefore did not exist, to the knowledge of the applicant, methods for improving the quality of meat through food, in the prior art
The applicant has surprisingly shown that the quality of the meat of animals of the swine family can be improved by introducing glycerol into their food or their drinking water.

 The present invention therefore relates to a process for treating swine, in particular pigs, with a view to improving the quality of their meat and, in particular, its water retention power, by incorporating glycerol, one or more several of its precursors and / or one or more of its metabolites to their food and / or to their drinking water.

 By precursors is meant the molecules which by metabolic degradation lead to glycerol, in particular sorbitol and fructose.

 This incorporation is carried out by methods known to those skilled in the art and conventional in the field to which the invention relates. The preparations of glycerol, its derivatives or its metabolites must meet the standards in force with regard to animal nutrition.

 The total concentration of glycerol is preferably between 1 and 10% by weight of the food and is advantageously of the order of 5%, but an equivalent amount can be added to the drinking water.

 This treatment method is preferably applied to swine, and in particular to pigs, but it can also be applied to the treatment of other animals such as turkeys, dairy cows, calves, laying hens and geese.

 This process notably allows increased water retention in the meat, this bound water not being released during cooking.

 According to the invention, the treatment is advantageously carried out for approximately 2 to 6 weeks and preferably for approximately 3 weeks.

Such a duration is particularly suitable if the total glycerol concentration is of the order of 5%
This duration is dependent on the total concentration of glycerol in the food and is thus adapted to the concentration used.
Preferably, the animals are treated at the end of their growth, that is to say in the few weeks before slaughter.

The present invention is illustrated by the following examples in which
- Figure 1A shows the longitudinal section of a carcass, Figure 1B showing details of the linear measurement sites and Figures 1C and 1D those of a cross section of the half-carcass at the points indicated.

 In these figures X1, X2, X4 and X'5 respectively represent the thicknesses of fat measured on the slit at the level of the Gluteus Medius muscle (X1), the thickness of fat measured laterally at 8 cm from the slit at the level of the junction between the third and fourth lumbar vertebrae (X2), and the thickness of fat measured laterally 6 cm from the slit, between the third and fourth ribs counted from the last rib (X4) and the thickness of the long muscle dorsal (X'5) measured at the same site as previously for (X4).

These marks are those used for measurements with the Fat-O-Meat'er device. (SFK, Denmark).

- Figure 2 shows a half-carcass cut according to the Parisian standard way, in which parts 1 to 7 respectively represent the loin, the ham, the shingle, the purlin, the chest, the chopping and ham set, and the feet
- Figure 3 is a diagram representing the variations of the dripping and cooking losses in the parts corresponding to the back (loin) and, to the ham, after the animal has been fed without glycerol or with a glycerol concentration of 5 % in food. The results are normalized as a percentage on the ordinate
EXAMPLE 1
Effect of dietary glycerol on meat quality and lipid synthesis in Large White pigs
The purpose of this study is to assess the effects of glycerol provided in the diet
- on pork growth,
- on some criteria reflecting the quality of the meat
- on the potential for lipid synthesis.

Experimental protocol.

1) Reqimes
4 batches of 10 neutered male Large White pigs receive between 35 and 100 kg of experimental diets according to a rationing plan used in the breeding of the Pig Research Station of Saint Gilles:
Weight of animal Amounts of food distributed
(kg) (kg / animal / day)
36-40 1.9
40-44 2.0
44-48 2.1
48-52 2.2
52-56 2.3
56-60 2.4
60-65 2.5
65-70 2.6
70-75 2.7
75-100 2.8
The diets are based on wheat and soybean meal. They contain 17% protein and 0.86% lysine.

The total lipid content is 4%.

 Two sources of lipids are used, either tallow (lots 1 and 2) or rapeseed oil (lots 3 and 4). These lipids are used because it has been shown that an insufficient rate of unsaturation of fatty acids could increase the deposit of lipids in the liver. It is therefore important to compare two fats having different contents of polyunsaturated fatty acids.

 In the experimental batches, a dose of 5% glycerol is introduced. Batches not treated with glycerol are tested in parallel (control batch). This dose was chosen according to studies carried out in other species (rats, poultry) which demonstrated a negative effect on growth from 10% of the weight mass of the diet.

LOTS 1 2 3 4
Fat Tallow Rapeseed Oil
Glycerol 0% 5% 0% 5%
These diets are isoenergetic.

Pigs reared in individual lodges are weighed once a week. The quantities of feed distributed and possibly refused by the animals are noted 2) Samples at slaughter
Different tissue samples are taken
- blood for the enzymatic assays of cholesterol, triglycerides, and free fatty acids,
- adipose tissue under the dorsal skin, before scalding, in the middle of the shingle; this tissue is immediately frozen in liquid nitrogen for the determination of the activities of the lipogenesis enzymes. It is the same for the intermuscular adipose tissue in ham, half-membrane. All these samples as well as an aliquot of liver will also be used to determine the fatty acid content and composition
- muscle tissue at the level of the semi-membranous and the long dorsal for measurement of exudate.

3) Measures
a) Growth performance
The consumption indices (CI) and the average daily earnings (GMQ) are calculated over the period between 35 and 60 kg (IC1 and GMQ1), then over the period of end of fattening between 60 and 100 kg (IC2 and GMQ2) and finally over the entire experimental period (ICt and GMQt).

b) Measurements made on the carcass
Body composition is estimated from linear measurements of fat and muscle thickness using the Fat-O-Meat'er (FOM) device. These measurements (Figure 1) make it possible to calculate a percentage of muscle and fat according to the equation established by B. DESMOULIN et al. (INRA Prod. Anim. 1988. 1 (1). P.59-64). Automatic measurement, similar to that used in industrial slaughterhouses, is supplemented by a standardized Parisian cutting (Figure 2) which allows the weight of muscle and fat to be calculated from another equation by the same author. This latter estimate is more precise than that obtained from the FOM.

The equations used are as follows
Estimation of the percentage of muscle (% MUS) of the half-carcass cut after a stay of 24 hours at 5 C from FOM measurements% MUS = 47.27 + 0.1165 P.NET- 0.1750 X1- 0.3086 X20.1425 X4 + 0.1691 X'5.

 Estimation of the percentage of fat in the half-carcass from FOM measurements% FAT = 9.185 - 0.02161 P. NET + 0.2807 X1 + 0.3150 X2 + 0.3037 X4 - 0.03035 X'5.

Estimation of the half-carcass muscle weight from the weights of the cutting pieces
Weight MUS = 296.9 - 201.0 P.DEMI + 1.395 LONGE + 1.144
HAM.

 The net weight (P.Net) is represented by the weight of a headless half-carcass, after 24 hours refrigeration.

Estimation of the weight of fatty tissue in the half-carcass from the weights of the cutting pieces
Fat weight = -816 + 1.63 BARRIER + 1.43 FAILURE + 0.52
CHEST.

c) Meat quality measures
- Direct measurement of the pH of the meat in the ham muscle (at the adductor) at times 45 minutes (after grinding the sample) and 24 hours after slaughter, by a pH meter with electrode
- Color measurement at the adductor.

The value scale ranges from 0 to 100. The highest reflectances are obtained on the lighter muscles.

 - Measurement of dripping losses: a sample of long dorsal muscle, without apparent waste, weighing approximately 100 g and having a thickness of approximately 1 cm is taken.

 It is weighed and suspended in a polyethylene bag in a cold room for 48 hours at 4 C. At the end of this period, the sample is again weighed and the loss of dripping is thus determined.

- Measurement of dripping and cooking losses in the ham using the HONIKEL technique (1987. In
Evaluation and Control of Meat Quality in Pigs. PV Tarrant,
G. Monin eds., Martinus Nijhoff Publishers, p.129-142). A piece of muscle (semi-membranous or long dorsal) is removed, trimmed and weighed (about 100 g and 2 cm thick).

The sample is placed in a polyethylene bag to avoid evaporation and placed for 48 hours in a cold room. At the end of this period, the sample is weighed and the difference in weight compared to time 0 gives the bleeding losses. Then, the sample is put under vacuum in a plastic bag and brought to 75 C for 45 minutes in a bain-marie. It is cooled under a stream of cold water for 30 minutes, then after partial drying, it is weighed. The cooking losses are thus determined as well as the total yield.

- NAPOLE test: representative of the industrial transformation of ham into Paris ham (Naveau et al. 1985
Techni-Pork 8, 6-13). The methodology is as follows
** sample at the slaughter of a cutlet (120 to 130g) of semi-membranous which is placed 24 h in cold room (4 C). A sample of approximately 100 g is trimmed and cut into small cubes (10 x 10 x 10 mm) and incubated in brine for 24 hours at 4 C (136 g / l of sodium nitrite salt mixture of 99.4% of ordinary salt and 0.6% sodium nitrite (E250))
** cooking for 10 min in a bain-marie at boiling point.

** draining on an inclined rack and cooling to room temperature for 2.5 hours. The difference of the weighs between the fresh weight and the drained weight indicates the water loss and makes it possible to calculate the technological yield
d) Determinations of blood parameters by automatic method with ISAMAT (ISABIO, Cachan, France) for cholesterol, using enzymatic tests (Bio-Mérieux), for triglycerides and free fatty acids.

e) The content of total linides is determined on the tissues from a methanol-chloroform extraction (FOLCH et al., 1957 J. Biol. Chem. 226, 497-509)
The fatty acid composition for all the sites sampled is determined by capillary gas chromatography after methylation with BF3 (Morrisson et al, 1964 J. Lipid.Res., 5,600-608). From this composition, the sums of saturated and polyunsaturated fatty acids are calculated as well as the coefficient of unsaturation.

 The different classes of liver lipids are determined by high pressure liquid chromatography (HPLC) coupled to a light scattering detector according to the STOLYWHO technique. et al. (1987, J. Liq. Chromatogr., 10, p 1237-1253). We can then calculate the share of polar or neutral lipid fractions.

 f) Measurement of the Potential of the activities of the enzymes of lipoqènèse.

 The potential for lipid synthesis is measured by determining the enzymatic activities of acetyl-CoA-carboxylase (ACX) (Chang et al. 1967 Biochem. Biophys. Res.

Comm., 28,682-686), of the malic enzyme (EM) (Hsu et al., 1969 Methods in enzymology, vol. XVII, 230-235, Lovenstein,
New-York-London) and glucose-6 phosphodehydrogenase (G6PDH) (Ficht et al., 1959, J. Biol.Chem 234, 1048-1051) at three sampling sites
- dorsal subcutaneous tissue,
- inter- and intramuscular adipose tissue at the level of the semi-membranous.

 ACX participates directly, with the fatty acid synthetase complex, in the de novo synthesis of fatty acids in adipose tissue. The malic enzyme and glucose-6 phosphodehydrogenase are dosed because they provide the NADPH essential for the biosynthesis of fatty acids.

 The assays of these three enzymes are carried out by radioenzymatic or colorimetric techniques known to those skilled in the art.

g) Statistical analysis
All results are analyzed by software
SAS to express the effects of glycerol (GLY), the source of lipids (LIP) and GLY / LIP interactions by analysis of variance.

Results
Reminder of the batch references: batches 1 and 2 have tallow as their lipid source, batches 3 and 4 receive rapeseed oil. Lots 1 and 3 did not receive glycerol and lots 2 and 4 received glycerol.

1) Growth performance
Consumption was identical for all animals and no refusal of the food was observed.

The values of the consumption indices (CI) and the average daily earnings (GMQ) are reported in table 1. In pigs receiving glycerol, an increase in the consumption index is observed and a decrease in the
GMQ whatever the period considered. These variations are not significant. The effects of the lipid source are also not significant and there is no interaction between the effects of glycerol and the lipid source.

 These observations are in line with those of other studies carried out in rats or chickens which have shown that glycerol depreciates (therefore increases the absolute value) the consumption index. In some cases, this effect was even very significant if the glycerol dose was close to or greater than 10%.

TABLE 1
VALUES OF CONSUMPTION AND GMO INDICES (ka / d)
IC1 IC2 ICt GMQ1 GMQ2 GMQt
LOT 1 3.00 3.08 3.05 0.656 0.842 0.761
LOT 2 3.18 3.22 3.21 0.620 0.809 0.721
LOT 3 2.99 3.00 2.99 0.653 0.841 0.755
LOT 4 3.03 3.21 3.14 0.653 0.811 0.740
ETR 0.26 0.22 0.20 0.050 0.047 0.041
GLY, LIP, GLY / LIP effects not significant for all parameters
ETR denotes the standard deviation of the residual and GLY / LIP the statistical interaction between the source of lipids and the presence of glycerol.

The characteristics of the carcass (Table 2) show no significant effect of the intake of glycerol or the effect of the source of lipids on the parameters considered.
The muscle weight increases in relation to the ingestion of glycerol in animals receiving tallow as a source of lipids and decreases for other treatments. The weight of fatty tissue increases with the ingestion of glycerol without the effects being significant.

It therefore seems that dietary glycerol has no significant effect on the tissue composition of the carcass
TABLE 2
CHARACTERISTIOUES OF THE CARCASS. ESTIMATION OF THE CONTENTS IN
FABRICS (%? BASED ON DIET GLYCEROL SUPPLY
Weight (kg) Estimate Estimate Thickness
FOM carcass "cut" back fat
(mm)
fatty muscle fatty muscle
LOT 1 82.5 50.24 27.14 48.65 26.98 19
LOT 2 81.7 50.12 26.87 49.04 28.23 20
LOT 3 82.7 49.40 26.70 48.77 26.92 19
LOT 4 82.1 49.51 27.93 47.88 28.53 19
ETR 2.1 2.02 2.52 1.89 2.57 3
GLY, LIP, GLY / LIP effects not significant for all parameters
The results of the standardized Parisian cutting of half of the carcass (Table 3) show that for most pieces there is no evidence of significant effects of glycerol, with the exception of the tip, the weight of which is higher in animals receiving glycerol (P <O, Ol): this may be related to the activity of lipid synthesis enzymes which is important in this tissue.

TABLE 3
WEIGHT OF THE HALF-CARCASE CUTTING PIECES (in grams
LOT 1 LOT2 LOT3 LOT4 ETR GLY purlin 614 741 681 770 142 P <0.0l (l) shaft 154 150 152 144 19 NS kidney 16287 16040 15942 16151 631 NS loin 11486 11311 11476 11275 425 NS bardière 4782 4909 4797 4907 573 NS ham 8,374 8,273 8,461 8,260 307 NS chop + 6,317 6,235 6,392 6,168,284 NS chest knuckles 4,261 4,022 4,028 4,534 447 NS
NS = not significant. (1) P <0.01 indicates a significant glycerol treatment effect compared to the control batch.

The various experimental data seem to show that, in pigs, dietary glycerol has no really significant action on zootechnical performances and on the energy conversion of food.
There is, however, a tendency for food efficiency to deteriorate (non-significant increase in the consumption index) in relation to a slight increase in adiposity expressed by the weight of the tip.

2) Color and PH
The measurements carried out (Table 4) show no variation in color of the meat between all the batches.

 The values of the pH at 45 minutes and the pH at 24 hours do not undergo significant variations.

TABLE 4
MEAT ORAL MEASUREMENTS
pH 45 min pH 24 h color (1)
LOT 1 6.10 5.76 45
LOT 2 6.13 5.79 44
LOT 3 6.18 5.74 46
LOT 4 6.18 5.75 46
ETR 0.18 0.19 6
GLY, LIP, GLY / LIP effects not significant for all parameters (1) Color index equal to 100 for a white surface.

 3) Water retention power.

 The introduction of glycerol into the diet (Table 5) significantly reduces the dripping losses of the long dorsal muscle and the semi-membranous muscle. It is the same for the cooking losses of the semi-membranous. These results therefore reflect an improvement in the water retention capacity of the muscles (Figure 3).

TABLE 5
WATER RETENTION (as% of Fresh Weight)
Drip loss Total loss
after cooking
Long dorsal Half-member. Half membranous
LOT 1 2.19 1.81 30.12
LOT 2 1.73 1.32 26.59
LOT 3 2.35 1.85 28.73
LOT 4 1.78 1.49 24.54
ETR 0.55 0.40 3.54
Effects
GLY P <0.005 P <0.001 P <0, O01
LIP NS NS NS
GLY / LIP NS NS NS
4) Analysis of blood parameters
Cholesterolemia increases in animals receiving glycerol (GLY P <0.01) (Table 6). The blood level of triglycerides decreases while that of fatty acids increases but these variations are not significant. Dietary glycerol intake therefore seems to lead to an increase in cholesterolemia, whereas on the contrary, a variation in the triglyceride level was expected.

TABLE 6
Results of different blood parameters (q / l)
Cholesterol Triglycerides Free fatty acids
LOT 1 0.88 0.52 1.39
LOT 2 0.94 0.45 1.52
LOT 3 0.86 0.54 1.18
LOT 4 0.94 0.50 1.37
ETR 0.09 0.13 0.57
GLY P effects <0.01 NS NS
LIP NS NS NS
GLY / LIP NS NS NS
5) Total lipid content of tissues.

 The total lipid content (table 7) of the muscles tends to increase with the introduction of glycerol, but not significantly. In the liver, the decrease in the accumulation of total lipids is at the limit of statistical significance (GLY P <O.ll). In adipose tissue, the percentage of lipids is similar between batches.

TABLE 7
Total lipid content (%)
Adipose tissue Half-Liver Muscle
membranous skin
internal back
LOT 1,79.79 76.07 3.50 3.75
LOT 2 79.17 77.39 3.88 3.56
LOT 3 79.66 79.29 3.58 3.87
LOT 4 80.44 76.72 3.77 3.67
ETR 3.61 4.23 0.43 0.36
GLY, LIP, GLY / LIP NS effects for all parameters.

 The fact that the total lipid content does not increase may come as a surprise since glycerol is reputed to be lipid-lowering, at least in rats, hens and cows. The decrease in lipids stored in the liver is an observation opposite to those made in other species (having received doses of glycerol higher by 10 to 20%, however).

 These results are related to the absence of a significant effect of the glycerol supply on the proportion of fatty tissue in the carcass.

 6) Composition of fatty acids in tissues.

 The fatty acid composition reported as a percentage of total fatty acids for the different sites is reported in Tables 8 to 11.

The effect of dietary lipids on the fatty acid composition of adipose tissue is once again confirmed
In the two adipose tissues, dorsal subcutaneous and intermuscular, a decrease in the level of myristic acid (C14: 0) is observed in animals having received glycerol (Lots 2 and 4, Tables 8 and 9). This variation is difficult to explain. The content of oleic acid increases with the addition of glycerol (P <0.OOl) while that of linoleic and linolenic acids decreases (P <0.01). The weight of the shingle increasing (not significantly) with the supply of glycerol, the variations in C18: 2 and C18: 3 correspond to a phenomenon of dilution of these fatty acids, exclusively of food origin because they cannot be synthesized by animal.

Overall these variations lead to a decrease in the coefficient of unsaturation of fatty acids
The main variations in muscle are observed for C14: 0 which decreases significantly with food intake (GLY P <0.001). C16: 0 decreases while C18: 1 increases in animals receiving glycerol (GLY P <0.01). This effect is mainly demonstrated in the animals of the batches receiving a tallow-based food (LIP P <0.01), and there is also a GLY * LIP interaction (P <0.Ol).

In the liver, no significant variation is observed for all fatty acids. The effect of the lipidic nature of the diet and mainly the amount of polyunsaturated fatty acids is therefore not confirmed in pigs receiving dietary glycerol
7) Determination of the lipid classes of the liver
A set of lipid classes could be identified (Table 12). In some cases, the peaks are not sufficiently well separated and are grouped together for interpretation. The identified peaks are
- triglycerides with cholesterol esters
TG
- cholesterol: CHOL
- diglycerides with monoglycerides: DG
- free fatty acids: AGL
- cardiolipids: CL
- phosphatidyl-ethanolamines: PL
- phosphatidyl-inositols with phosphatidyl serines: PIS
- phosphatidyl-cholines: PC
- sphingomyelins: SM.

 From these data, the sum of the neutral lipid (TG + CHOL + DG + AGL) and polar lipid (CL + PL + PIS + PC + SM) fractions is calculated.

 The triglyceride content increases significantly under the effect of dietary glycerol supplementation (GLY P <0.05).

 The cholesterol content also increases but with a double effect GLY (P <0.05) and LIP (P <0.05), without evidence of interaction. These variations were found in the blood compartment.

 The other classes of neutral lipids do not vary.

The intake of glycerol leads overall to a significant increase in the total fraction of neutral lipids (GLY
P <0.01), which is reflected by the increases in classes TG and CHOL.

 Glycerol has no effect on the entire polar lipid fraction.

 8) Measurement of the activity potential of the lipogenesis enzymes.

 The results of the activity measurements of the lipogenesis enzymes are affected by a great variability (Table 13), which is conventionally observed in these animals.

 The enzymatic activity of acetyl-CoA-carboxylase increases not significantly in the adipose tissue under the dorsal skin, the intermuscular adipose tissue of the ham and does not vary in the intramuscular adipose tissue.

 Since the NADPH substrate is not a limiting factor under these conditions, glycerol therefore does not modify the synthesis potential of the lipogenesis enzymes.

 The activity of the malic enzyme (EM) significantly increases in the dorsal subcutaneous adipose tissue and the intermuscular adipose tissue of the ham under the effect of glycerol. The amount of NADPH present will therefore not be a limiting factor for the synthesis of lipids. This observation is also confirmed by the very significant increase in G6PDH (glucose 6-phosphate dehydrogenase) in the muscle.

 Thus glycerol does not cause any modification of lipid synthesis although the necessary cofactor is present in sufficient quantity. These results partly explain the absence of significant variation in the total lipid content of the tissues and of the adipose mass of the carcass observed in these same animals. Therefore, in pigs, glycerol does not seem to be a lipid-lowering factor like in rats, poultry or cattle.

 Glycerol increases the activity of G6PDH. This enzyme belongs to the cycle of pentose phosphates. We can therefore think that this metabolic pathway is stimulated. It is possible that dietary glycerol, the concentration of which probably increases in the circulating and tissue medium, by retroactive regulation, inhibits the in vivo transformation of glycerol-3 phosphate into glycerol.

Consequently, the previous reaction (dihydroxyacetonephosphate (DAP) to glycerol-3-P) is also inhibited, which leads to an increase in dihydroxyacetonephosphate. This compound being preferentially present in the pentose phosphate pathway, this can therefore explain the stimulation of this pathway and the increase in the activity of G6PDH.

In conclusion
The dose of glycerol retained did not significantly reduce growth performance
The quality of the meat is improved thanks to a reduction in dripping and cooking losses.

Observations made in other species showing a hyperlipemic effect of glycerol are not confirmed in pigs: the activities of the enzymes of lipogenesis are not modified. However, non-significant increases in the adipose mass deposited and in lipid synthesis are observed; these trends are consistent with higher fat deposition in animals receiving dietary glycerol
EXAMPLE 2
Effects of glycerol in pigs from a Larqe cross
White x Piétrain.

 10 Large White x Piétrain crossbred pigs are reared individually and on a restricted diet.

Lot 1 control lot without glycerol
Lot 2 treated lot, 5% glycerol in food
between 60 and 100 kg bodyweight
Lot 3 treated lot, 5% glycerol in food
between 80 and 100 kg bodyweight.

Water retention in the Lonq Dorsal muscle.

 These results (expressed in%) obtained by the Honikel technique on the long dorsal muscle are representative of water losses during cooking (Table 14).

 The bleeding losses are identical between the animals. The experimental treatment tends to decrease the water losses of the long dorsal muscle during cooking and consequently to increase the total yield. However, this effect is not significant (limit P <0.1).

 The study on Large-White pigs showed a beneficial effect on the bleeding losses of the long dorsal (P <0.005).

This is not the case with crossed animals. This can be explained by the fact that the losses of bleeding particularly important for this experiment, are certainly a consequence of the genetic choice (less than 2% of water loss for Large-White pigs and more than 10% for crusaders ). The strong PES effect of Pietrain animals is therefore clearly highlighted.

 NAPOLE technological performance and transformation into Paris ham.

The transformation into Paris ham was carried out by the Technical Center for the Salting of Charcuterie and
Canned Meats (CTS CCV) at Maisons-Alfort.

 The growing glycerol treatment (table 15) increases the NAPOLE technological yield (P <0.01). Weight gain is significantly greater (P <0.05) with the longest treatment. These results are confirmed by the actual transformation into Paris ham (P <0.007) where the weight gain during the transformation is even more marked (Figure 3).

I1 is admitted by the bibliography that there is a good correlation between the NAPOLE test and the transformation into Paris ham (between (+) 0.7 and (+) 0.8), which is again confirmed
The values assigned by the same letter in column are not significantly different at the 5% threshold.

 It seems that the effects on the semi-membranous muscle of the ham are greater in pigs treated from 60 kg than in those treated from 80 kg.

The beneficial effect of glycerol at a dose of 5% on the water loss of the meat would therefore be related to the duration of the treatment (P <0.05 for NAPOLE between the longest duration and the control).

On the other hand, for the whole ham, the differences between the durations of the treatment are not highlighted: this can be explained by the fact that the measurement
NAPOLE concerns a single muscle while transformation concerns a set of muscles which can react to glycerol from food in various ways. This hypothesis is confirmed by the different results obtained between the long dorsal muscle and the semi-membranous muscle for the same animal.

However, this experiment carried out on animals from a commercial type crossing reinforces the interest of an application to production TABLE 8
Composition of fatty acids at the dorsal subcutaneous TA
Lot 1 Lot 2 Lot 3 Lot 4 ETR% of total fatty acids
GLY LIP GLY / LIP
C14: 0 (1) 1.32 1.18 1.21 1.02 0.18 ** * NS
C16: 0 (2) 26.21 25.25 25.07 24.07 1.32 NS * NS
C16: 1 (3) 3.00 2.63 2.02 1.94 0.64 NS ** NS
C18: 0 (4) 12.75 12.58 11.21 12.05 1.20 NS * NS
C18: 1 (5) 48.11 50.67 47.60 50.20 1.5 *** * NS
C18: 2 (6) 8.35 7.43 11.51 9.76 1.20 ** *** NS
C18: 3 (7) 0.18 0.14 1.25 0.84 0.23 *** *** **
C20: 1 (8) 0.08 0.12 0.13 0.11 0.06 NS NS NS
Insat. 1.15 1.13 1.22 1.18 0.02 *** *** NS * P <0.05: ** P <0.01: *** P <0.001.

Insat. is the unsaturation coefficient expressed by the ratio: (% of each unsaturated fatty acid x number of bonds) of the fatty acid (% of unsaturated fatty acid)
ETR = residual standard deviation (1) myristic acid (5) oleic acid (2) palmitic acid (6) linoleic acid (3) palmitoleic acid (7) linolenic acid (4) stearic acid (8) arachidic acid TABLE 9
Fatty acid composition of intermuscular adipose tissue in ham
LOT 1 LOT2 LOT3 LOT4 ETR% of total fatty acids
GLY LIP GLY / LIP
C14: 0 1.42 1.28 1.24 1.09 0.15 * ** NS
C16: 0 26.61 25.51 25.05 24.04 1.53 NS * NS
C16: 1 3.22 3.12 2.42 3.04 0.51 NS ** NS
C18: 0 12.09 11.75 12.05 10.98 1.22 NS NS NS
C18: 1 48.04 50.71 46.30 49.83 2.00 ** ** NS
C18: 2 8.29 7.36 11.25 10.03 1.42 * *** NS
C18: 3 0.27 0.19 1.57 0.90 0.67 * *** NS
C20 :: 1 0.07 0.08 0.11 0.10 0.05 NS NS NS
Insat. 1.15 1.12 1.23 1.18 0.02 *** *** NS * P <0.05 ** P <0.01: *** P <0.001.

TABLE 10
Composition of fatty acids in the semi-membranous muscle
LOT 1 LOT2 LOT3 LOT4 ETR% of grastotal acids
GLY LIP GLY / LIP
C14: 0 1.39 1.17 1.26 1.18 0.12 *** NS NS
C16: 0 26.13 24.26 24.46 24.11 1.16 ** ** *
C16: 1 3.69 3.28 3.28 3.40 0.81 NS NS NS
C18: 0 10.57 10.15 10.31 10.42 0.97 NS NS NS
C18: 1 51.44 54.50 51.43 51.57 1.89 ** ** **
C18: 2 6.00 5.84 7.70 8.19 1.15 NS *** NS
C18: 3 0.07 0.07 0.52 0.40 0.11 NS *** NS
C20: 4 1.75 1.72 1.61 2.06 0.49 NS NS NS
Insat. (1) 1.18 1.17 1.21 1.23 0.03 NS *** NS * P <0.05: ** P <0.01: *** P <0.001 (1) Insat . is the unsaturation coefficient expressed by the ratio (% of each unsaturated fatty acid x number of bonds) of the fatty acid (% of unsaturated fatty acid)
ETR = standard deviation of the residual.

TABLE 11
Fatty acid composition of liver lipids (1)
LOT 1 LOT 2 LOT 3 LOT 4 ETR GLY LIP GLY * LIP
C14: 0 0.40 0.34 0.31 0.26 0.13 NS NS NS
C16: 0 18.08 17.80 17.31 16.39 2.45 NS NS NS
C16: 1 0.56 0.63 0.62 0.56 0.31 NS NS NS
C18: 0 30.59 27.72 31.34 30.20 3.94 NS NS NS
C18: 1 27.93 28.36 25.96 26.66 3.14 NS NS NS
C18: 2 15.36 15.98 16.28 16.48 2.17 NS NS NS
C18: 3 0.05 0.06 0.10 0.08 0.12 NS NS NS
C20: 4 6.99 9.07 8.06 9.32 3.49 NS NS NS
Insat. 1.71 1.80 1.78 1.83 0.17 NS NS NS
ETR: Standard Deviation of the Residual.

(1) Percentage of total fatty acids.

TABLE 12
Identification of the different lipid classes of the time (%)
Lot 1 Lot 2 Lot 3 Lot 4 ETR (1) GLY LIP GLY * LIP
TG 11.86 14.54 11.44 12.54 3.11 * NS NS
CHOL 4.73 6.10 6.28 6.37 1.19 * * NS
DG 0.34 0.30 0.22 0.26 0.19 NS NS NS
AGL 2.38 2.44 1.99 2.34 0.87 NS NS NS
CL 0.86 0.84 0.87 0.87 0.18 NS NS NS
PE 24.23 24.80 24.34 22.25 2.51 NS NS NS
PIS 8.82 8.15 8.61 7.32 1.95 NS NS NS
PC 42.01 38.35 44.40 43.49 5.66 NS * NS
SM 3.80 4.97 2.25 4.53 2.38 NS NS NS
In 19.33 23.40 19.95 21.52 3.56 ** NS NS
Ip 79.73 77.13 80.49 78.47 5.36 NS NS
In represents the total of lipids and Ip the total of polar lipids * P <0.05: ** P <0.01 (1) ETR = Standard Deviation of the Residual.

TABLE 13
Activity of lipogenesis enzymes: Acetyl CoA carboxylase (ACX). Malic enzyme (EM).

Glucose 6 Phospho Dehydrogenase (G6PDH) in the various tissues.

LOT 1 LOT 2 LOT 3 LOT 4 ETR (1) GLY EFFECT
S. CUT DORSAL
ACX 2.58 2.67 2.63 2.73 0.41 NS
EM 134.24 146.19 136.63 154.82 18.94 **
G6PDH 163.05 178.99 159.40 186.78 40.63 NS
ACX INTERMUSCULAR TISSUE 2.77 2.92 2.83 2.89 0.66 NS
EM 97.94 100.25 89.81 104.55 15.16 *
G6PDH 136.94 140.57 141.26 147.55 35.31 NS
ACX HALF-MEMBRANE MUSCLE 1.85 1.84 1.76 1.61 0.46 NS
EM 41.94 46.19 42.68 40.03 11.01 NS
G6PDH 8.74 15.67 8.11 19.21 5.75 ***
No significant effect for LIP or GLY / LIP: * P <0.05: ** P <0.01: *** 0 <0.001.

ACX activities are expressed in moles of HCO3- incorporated per minute and per gram of tissue.

EM and G6PDH are expressed in moles of NADPH formed per minute and per gram of tissue.

(1) Standard Deviation of the Residual.

TABLE 14
Effect of dietary glycerol on losses
of water when the long dorsal muscle is cooked
by the HONIKEL technique
Loss of bleeding Loss of cooking Yield
total
Lot T 11.78 26.01 65.23
Lot A 12.46 23.88 66.64
Lot B 11.49 24.92 66.47
ETR 2.24 2.69 2.81
GLY NS NS NS effect
TABLE 15
Effect of dietary cholesterol on
transformation of the semi-membranous muscle
(NAPOLE) and ham in Paris ham
NAPOLE Paris Ham
Yield Technological yield
Lot T 91.40a 76.82a
Lot A 95.08b 80.19b
Lot B 93.55ab 80.62b
ETR 2.89 2.67
GLY effect P <0.01 P <0.007

Claims (5)

 1. Process for the treatment of swine, in particular pigs, with a view to improving the quality of their meat and in particular its water retention power, by incorporating glycerol from one or more of its precursors and / or one or more of its metabolites to their food and / or drinking water  2. Method according to claim 1, characterized in that the total concentration of glycerol is between approximately 1% and 10% by weight of the food and / or drinking water  3. Method according to claim 2, characterized in that the total concentration of glycerol is of the order of 5%.  4. Method according to claim 3, characterized in that the treatment is carried out for approximately 2 to 6 weeks, and preferably for approximately 3 weeks.  5. Method according to claim 4, characterized in that the treatment is carried out at the end of the growth period