Edited by: Pietro Celi, DSM Nutritional Products, United States
Reviewed by: Surinder Singh Chauhan, University of Melbourne, Australia; Susana P. Alves, Faculdade de Medicina Veterinária da Universidade de Lisboa, Portugal; Cristina Mateus Alfaia, Faculdade de Medicina Veterinária da Universidade de Lisboa, Portugal
Specialty section: This article was submitted to Animal Nutrition and Metabolism, a section of the journal Frontiers in Veterinary Science
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This study examined the histological properties of
Bovine breeds are characterized by a specific phenotypic conformation, which is largely due to the effects of extensive genetic improvement (GI) over the last 50 years. With respect to bovine meat breeds, the goal of GI is to improve animal performance to increase the average daily gain and dressing yield. GI is obtained by a quantitative approach based on phenotypic animal measurements and more recently, by molecular selection. Some bovine breeds have been intensively genetically improved, with the result that their conformation perfectly meets the ideal productive characteristics, with a very high rearing and slaughtering performance. Conversely, some autochthonous bovine breeds, due to their original low productivity, have not been genetically improved, and their current characteristics and phenotypic conformation are quite similar to the original ones. Genetic improvements have affected not only the animal productivity but also the meat quality. In fact, by selecting for the phenotypic globosity of animals, a particular kind of muscle fiber has been selected, and the improved breeds show bigger fibers than native breeds (
The different types of muscle fibers also show a different lipid composition. In fact, especially lipids contained in the sarcolemma, such as phospholipids (PLs) and cholesterol, putatively have a higher content in the smaller fibers (the red ones) due to their longer total sarcolemma perimeter (TSP) (
Clearly, the phenotypic conformation, animal performance, and meat quality are also determined by the environment. In fact, genetic types react differently to the rearing system, depending on how they adapt to grazing or to particular soil and climatic conditions. Thus, the rearing system and animal movement might affect the muscle fiber distribution both from a histological and physiological point of view (
The aim of this experiment was to study the effect of breed [Maremmana (Ma) and Limousine (Lm)] and type of muscles [
The study was carried out on 10 female bovines (5 Ma and 5 Lm) from an organic farm located in Grosseto, in southern Tuscany (Italy). To avoid feed competition, the two animal groups were grazed in two adjoining pastures throughout the experimental period. Pasture was sampled once a month throughout experimental period. The chemical and the botanical composition of the pasture are shown in Table
Chemical composition of pasture and feed (g/100 g of DM) and botanical composition of pasture.
Pasture |
Hay | Concentrate | |||||
---|---|---|---|---|---|---|---|
SP | SU | AU | SE | ||||
DM (g/100 g of feed) | 18.8b | 33.2a | 31.8a | 2.55 | <0.01 | 86.6 | 89.5 |
Ether extract | 3.6 | 3.0 | 2.7 | 0.27 | 0.26 | 1.8 | 2.1 |
Crude protein | 11.5a | 7.7b | 5.1c | 0.34 | <0.01 | 8.0 | 14.6 |
NDF | 55.9c | 62.4b | 77.1a | 1.69 | <0.01 | 60.0 | 15.2 |
ADF | 31.0c | 39.3b | 53.2a | 1.49 | <0.01 | 37.7 | 6.3 |
ADL | 3.7c | 7.5b | 15.0a | 0.63 | <0.01 | 5.4 | 0.8 |
Ashes | 5.8 | 6.1 | 5.1 | 0.27 | 0.14 | 9.4 | 6.9 |
NSC | 4.4 | 6.9 | 3.2 | 0.25 | 0.21 | 20.8 | 61.2 |
FUs/kg of DM | 0.7a | 0.6b | 0.3c | 0.01 | 0.02 | 0.5 | 1.0 |
Leguminous | 21.4a | 6.0b | 4.7b | 3.12 | 0.02 | – | – |
Grasses | 45.6b | 76.4a | 49.8ab | 7.28 | 0.03 | – | – |
Other | 33.0b | 17.6c | 45.5a | 7.66 | 0.04 | – | – |
Yeld (ton of DM/ha) | 1.9a | 3.9a | 3.2a | 2.55 | <0.01 | – | – |
Since muscle fiber differentiation and growth are affected by animal age (
The abattoir was a public facility and was less than 10 km from the farm. The animals were slaughtered shortly after arrival.
The muscle sampling was performed when the animals were slaughtered and before the right-hand side of the carcass had cooled. Whole TB and SM muscles were collected. For the histological determinations, three 1 cm × 1 cm portions with the same length muscle were immediately sampled from each muscle. Each portion was then divided into three parts (proximal, intermediate, and distal) and immediately placed into a 50 mL test tube containing about 40 mL of formalin to preserve the sample until analysis. The sampling for chemical analyses was performed by the same procedure, except that the samples were immediately frozen until analysis.
Samples were fixed in 4% paraformaldehyde in 0.1 M phosphate-buffered saline (pH 7.4), dehydrated, and embedded in paraffin. Sections of 5 µm were cut by a microtome (Reichert-Jung). Sections were stained with Mallory’s Trichrome (Bio-Optica) modified to facilitate microscopic examination. The specimens were assessed under a Leitz Diaplan microscope (Nikon Eclipse Ni) connected to a digital image acquisition system (Nikon digital-sight DS-U1) with the help of the “NIS” program (NIS-Elements BR-4.13.00, Nikon Corporation, Tokyo Japan). For each of the acquired images, the number of muscle fibers (TNF), mean sarcolemma perimeter (MSP), TSP, and cross-sectional area (CSA) were reported.
The moisture content was determined by weight difference by placing the samples into a ventilated oven at 105°C for 24 h. Crude fat in animal feed was determined by extracting 0.5 g of the sample with petroleum ether using an XT10 Ankom apparatus (Macedon, NY, USA) without acid hydrolysis, according to the AOCS official procedure AM 5-04. Protein content was determined by Kjeldahl methods according to the AOAC official procedure AOAC 981.10. Crude fiber and fiber fraction (neutral detergent fiber, acid detergent fiber, and acid detergent lignin) analyses were performed by the Ankom technology filter bag technique (Macedon, NY, USA), AOAC approved procedure Ba 6a 05. The mineral level by weight difference was assessed by placing samples into a high temperature muffle furnace where the temperature was maintained at 550°C. Carbohydrate percentage was calculated as complement to 100 of the sum of fat, protein, and minerals.
Total lipids (TLs) were extracted from 5 g of sample with a chloroform/methanol mixture (2:1, v/v) according to Rodriguez-Estrada et al. (
The cholesterol was quantified according to Boselli et al. (
Data were analyzed using the following linear model by JMP9 software (SAS Institute Inc., Cary, NC, 2010):
Least-square means with their SEs were recorded, and treatment effects were declared significant at
Animals were approximately 19 months old at the time of slaughter (Ma 18.9 ± 0.9 months; Lm 18.5 ± 1.0 months). Live weight at the time of slaughter was significantly higher in Ma than in Lm (570.8 ± 15.3 vs 485.1 ± 17.2 kg,
Breed was also a significant variation factor for proximate composition. In fact, Ma muscle was higher in dry matter and lipid content than the Lm (Table
Proximate composition and lipid fraction composition of SM and TB muscles of Ma and Lm breeds.
Breed |
Muscle |
SE | Significance |
|||||
---|---|---|---|---|---|---|---|---|
Lm | Ma | TB | SM | Breed | Muscle | Breed × muscle | ||
Dry matter (g/100 g of muscle) | 24.3 | 26.4 | 25.2 | 25.4 | 0.6 | * | ns | ns |
TLs (g/100 g of mDM) | 4.3 | 9.4 | 7.7 | 6.4 | 1.6 | * | * | ns |
Crude proteins (g/100 g of mDM) | 86.0 | 85.1 | 87.3 | 83.8 | 0.7 | ns | ** | ns |
Ashes (g/100 g of mDM) | 4.7 | 4.1 | 4.4 | 4.4 | 0.2 | * | ns | ns |
Carbohydrates (g/100 g of mDM) | 4.8 | 1.3 | 0.8 | 5.3 | 0.3 | * | ** | ns |
NL (g/100 g TL) | 65.6 | 72.6 | 70.1 | 68.1 | 2.5 | * | ns | ns |
PL (g/100 g TL) | 28.3 | 21.5 | 23.9 | 25.9 | 2.7 | * | ns | ns |
FFA (g/100 g TL) | 1.6 | 1.9 | 2.1 | 1.5 | 0.4 | ns | ns | ns |
Chol (mg/100 g muscle) | 37.7 | 39.8 | 39.3 | 38.2 | 3.0 | ns | ns | ns |
Chol (g/100 g TL) | 3.0 | 2.1 | 2.6 | 2.5 | 0.4 | * | ns | ns |
Muscle significantly affected the carbohydrate and lipid contents, as the former was higher in SM than in TB, and the latter was higher in TB than in SM (Table
Breed was also a significant variation factor for the histological characteristics (Table
Muscle fibers histological characteristics of SM and TB muscles from Ma and Lm breeds.
Breed |
Muscle |
SE | Significance |
|||||
---|---|---|---|---|---|---|---|---|
Lm | Ma | TB | SM | Breed | Muscle | Breed × muscle | ||
TNF (No) | 80.5 | 60.8 | 75.0 | 66.2 | 2.6 | *** | * | ns |
CSA (μm2) | 2,356 | 5,472 | 3,332 | 4,496 | 1,457 | * | ns | ns |
MSP (μm) | 171.5 | 259.7 | 227.8 | 203.5 | 53.6 | * | ns | ns |
TSP (mm) | 14.2 | 12.2 | 14.0 | 12.3 | 0.4 | * | ns | ns |
Table
Pearson correlations (above diagonal) and correlation significance (below diagonal).
TSP | TL | PL | NL | Chol-m | Chol-TL | |
---|---|---|---|---|---|---|
TSP | 1.000 | −0.505 | 0.658 | −0.657 | −0.383 | 0.720 |
TL | ** | 1.000 | −0.900 | 0.808 | 0.828 | −0.812 |
PL | * | *** | 1.000 | −0.911 | −0.697 | 0.940 |
NL | * | ** | *** | 1.000 | 0.668 | −0.844 |
Chol-m | ns | ** | ns | ns | 1.000 | −0.530 |
Chol-TL | ** | ** | *** | *** | ns | 1.000 |
Phospholipids and NLs showed a specific fatty acid composition. PLs were high in PUFA, mainly represented by linoleic acid (C18:2 n-6), and in PUFA with acyl chain constituted by 20 carbon atoms or more. This fatty acid class consisted of about 20% of total fat and were mostly represented by arachidonic acid (C20:4 n-6), eicosapentaenoic acid (EPA, C20:5 n-3), docosapentaenoic acid (DPA, C22:5 n-3), and docosahexaenoic acid (DHA, C22:6 n-3) (Table
Fatty acid composition of PLs of SM and TB muscles from Ma and Lm breeds (g/100 g of FA from PL).
Breed |
Muscle |
SE | Significance |
|||||
---|---|---|---|---|---|---|---|---|
Lm | Ma | TB | SM | Breed | Muscle | Breed × muscle | ||
TL (g/100 g of muscle) | 4.34 | 9.43 | 7.67 | 6.38 | 0.52 | * | * | ns |
PL (g/100 g of TL) | 28.34 | 21.54 | 23.95 | 25.93 | 2.68 | * | ns | ns |
Total FA (g/100 g of FA from PL) | 19.62 | 14.73 | 16.56 | 17.80 | 0.37 | * | ns | ns |
C15:0 | 0.15 | 0.51 | 0.24 | 0.41 | 0.14 | ns | ns | ns |
C16:0 | 21.74 | 21.68 | 22.14 | 21.28 | 1.38 | ns | ns | ns |
C17:0 - |
0.45 | 0.35 | 0.55 | 0.25 | 0.07 | * | ns | ns |
C16:1 |
0.57 | 0.48 | 0.34 | 0.71 | 0.13 | ns | ns | ns |
C16:1 |
0.78 | 1.04 | 0.90 | 0.92 | 0.11 | ns | ns | ns |
C17:0 | 0.68 | 0.46 | 0.61 | 0.54 | 0.12 | ns | ns | ns |
C18:0 - |
0.09 | 0.13 | 0.14 | 0.09 | 0.10 | ns | ns | ns |
C17:1 |
0.52 | 0.50 | 0.49 | 0.53 | 0.12 | ns | ns | ns |
C18:0 | 7.03 | 7.11 | 7.10 | 7.03 | 0.46 | ns | ns | ns |
C18:1 |
18.78 | 25.34 | 21.24 | 22.88 | 1.81 | * | ns | ns |
C18:1 |
1.22 | 1.59 | 1.20 | 1.61 | 0.68 | ns | ns | ns |
C18:1 |
0.57 | 0.47 | 0.53 | 0.51 | 0.12 | ns | ns | ns |
C18:2 n-6 | 24.64 | 20.37 | 23.62 | 21.39 | 1.37 | * | ns | ns |
C18:3 n-3 | 1.98 | 1.47 | 1.78 | 1.66 | 0.20 | ns | ns | ns |
C20:2 n-6 | 0.25 | 0.32 | 0.26 | 0.31 | 0.04 | ns | ns | ns |
C22:0 | 3.01 | 1.97 | 2.74 | 2.23 | 0.04 | ns | ns | ns |
C20:3 n-6 | 10.22 | 8.61 | 9.82 | 9.01 | 0.26 | * | ns | ns |
C20:4 n-6 | 0.13 | 0.07 | 0.14 | 0.06 | 0.75 | ns | ns | ns |
C23:0 | 1.83 | 2.84 | 1.46 | 3.21 | 0.04 | ns | ns | ns |
C20:5 n-3 | 0.87 | 1.42 | 0.86 | 1.44 | 1.85 | ns | ns | ns |
C22:4 n-6 | 3.23 | 2.45 | 2.92 | 2.76 | 0.60 | ns | ns | ns |
C22:5 n-3 | 0.43 | 0.36 | 0.31 | 0.49 | 0.29 | ns | ns | ns |
C22:6 n-3 | 0.15 | 0.51 | 0.24 | 0.41 | 0.20 | ns | ns | ns |
SFA | 30.67 | 30.76 | 31.31 | 30.11 | 1.64 | ns | ns | ns |
MUFA | 22.92 | 29.51 | 24.97 | 27.46 | 1.70 | * | ns | ns |
PUFA | 46.42 | 39.73 | 43.72 | 42.44 | 2.66 | ns | ns | ns |
Fatty acid composition of NLs of SM and TB muscles from Ma and Lm breeds (g/100 g FA from NL).
Breed |
Muscle |
SE | Significance |
|||||
---|---|---|---|---|---|---|---|---|
Lm | Ma | TB | SM | Breed | Muscle | Breed × muscle | ||
TL (g/100 g of muscle) | 4.34 | 9.43 | 7.67 | 6.38 | 0.52 | * | * | ns |
NL (g/100 g of TL) | 65.65 | 72.59 | 70.12 | 68.12 | 2.52 | * | ns | ns |
Total FA (g/100 g FA from NL) | 62.04 | 68.92 | 66.80 | 64.16 | 0.18 | * | ns | ns |
C12:0 | 0.18 | 0.18 | 0.18 | 0.18 | 0.03 | ns | ns | ns |
C14:0 | 1.45 | 2.47 | 2.14 | 1.79 | 0.36 | ns | ns | ns |
C14:1 |
0.56 | 0.86 | 0.71 | 0.71 | 0.11 | ns | ns | ns |
C15:0 | 0.31 | 0.30 | 0.30 | 0.31 | 0.03 | ns | ns | ns |
C16:0 | 22.63 | 24.11 | 23.21 | 23.54 | 1.23 | ns | ns | ns |
C17:0 - |
0.30 | 0.27 | 0.29 | 0.28 | 0.02 | ns | ns | ns |
C16:1 |
0.19 | 0.18 | 0.18 | 0.18 | 0.02 | ns | ns | ns |
C16:1 |
4.84 | 5.30 | 5.10 | 5.04 | 0.38 | ns | ns | ns |
C17:0 - |
0.13 | 0.19 | 0.15 | 0.17 | 0.02 | * | ns | ns |
C17:0 | 0.84 | 0.69 | 0.79 | 0.75 | 0.03 | * | ns | ns |
C17:1 |
0.85 | 0.69 | 0.74 | 0.79 | 0.12 | ns | ns | ns |
C18:0 | 10.66 | 9.07 | 9.97 | 9.76 | 0.69 | ns | ns | ns |
C18:1 |
0.16 | 0.14 | 0.16 | 0.14 | 0.02 | ns | ns | ns |
C18:1 |
0.23 | 0.23 | 0.24 | 0.22 | 0.02 | ns | ns | ns |
C18:1 |
0.53 | 0.34 | 0.46 | 0.41 | 0.08 | ns | ns | ns |
C18:1 |
0.68 | 0.58 | 0.67 | 0.60 | 0.09 | ns | ns | ns |
C18:1 |
0.25 | 0.22 | 0.23 | 0.24 | 0.03 | ns | ns | ns |
C18:1 |
47.32 | 46.80 | 46.88 | 47.23 | 1.42 | ns | ns | ns |
C18:1 |
1.97 | 2.13 | 2.09 | 2.02 | 0.17 | ns | ns | ns |
C18:1 |
0.30 | 0.34 | 0.33 | 0.31 | 0.19 | ns | ns | ns |
C18:1 |
0.38 | 0.48 | 0.43 | 0.43 | 0.03 | ns | ns | ns |
C18:1 |
0.16 | 0.16 | 0.16 | 0.16 | 0.04 | ns | ns | ns |
C18:2 |
2.30 | 1.94 | 2.20 | 2.04 | 0.03 | ns | ns | ns |
C18:2 n-6 | 0.22 | 0.30 | 0.27 | 0.24 | 0.16 | ns | ns | ns |
C20:1 |
0.33 | 0.34 | 0.34 | 0.33 | 0.04 | ns | ns | ns |
C18:3 n-3 | 0.29 | 0.30 | 0.30 | 0.29 | 0.03 | ns | ns | ns |
C18:2 |
0.22 | 0.13 | 0.22 | 0.14 | 0.04 | ns | ns | ns |
C23:0 | 0.18 | 0.18 | 0.18 | 0.18 | 0.03 | ns | ns | * |
SFA | 37.37 | 38.02 | 37.86 | 37.53 | 1.87 | ns | ns | ns |
MUFA | 59.27 | 59.01 | 58.93 | 59.35 | 1.69 | ns | ns | ns |
PUFA | 3.47 | 3.09 | 3.33 | 3.24 | 0.26 | ns | ns | ns |
Breed was a significant variation factor with respect to total fatty acid composition (Table
Fatty acid composition of TL of SM and TB muscles from Ma and Lm breeds (g/100 g of TL).
Breed |
Muscle |
SE | Significance |
|||||
---|---|---|---|---|---|---|---|---|
Lm | Ma | TB | SM | Breed | Muscle | Breed × muscle | ||
TL (g/100 g of muscle) | 4.34 | 9.43 | 7.67 | 6.38 | 0.52 | * | * | ns |
C14:0 | 0.82 | 1.67 | 1.23 | 1.27 | 0.25 | ns | ns | ns |
C14:1 |
0.22 | 0.50 | 0.35 | 0.37 | 0.08 | ns | ns | ns |
C15:0 | 0.18 | 0.21 | 0.21 | 0.19 | 0.02 | ns | ns | ns |
C16:0 | 12.51 | 16.90 | 14.69 | 14.72 | 1.46 | ns | ns | ns |
C17:0 - |
0.24 | 0.21 | 0.23 | 0.23 | 0.02 | ns | ns | ns |
C16:1 |
2.03 | 3.05 | 2.52 | 2.57 | 0.32 | ns | ns | ns |
C17:0 | 0.46 | 0.51 | 0.49 | 0.47 | 0.04 | ns | ns | ns |
C17:1 |
0.41 | 0.47 | 0.45 | 0.43 | 0.02 | ns | ns | ns |
C18:0 | 6.98 | 7.41 | 7.42 | 6.97 | 0.45 | ns | ns | ns |
C18:1 |
0.26 | 0.20 | 0.25 | 0.21 | 0.03 | ns | ns | ns |
C18:1 |
0.34 | 0.37 | 0.39 | 0.32 | 0.04 | ns | ns | ns |
C18:1 |
0.17 | 0.14 | 0.17 | 0.14 | 0.01 | ns | ns | ns |
C18:1 |
19.99 | 27.54 | 23.87 | 23.67 | 1.88 | * | ns | ns |
C18:1 |
1.13 | 1.27 | 1.27 | 1.13 | 0.06 | ns | ns | ns |
C18:1 |
0.22 | 0.24 | 0.24 | 0.23 | 0.02 | ns | ns | ns |
C18:1 |
0.16 | 0.26 | 0.21 | 0.21 | 0.03 | * | ns | ns |
C18:2 n |
5.47 | 3.24 | 4.59 | 4.12 | 0.41 | ** | ns | ns |
C18:3 n-3 | 0.49 | 0.36 | 0.43 | 0.41 | 0.03 | ns | ns | ns |
C20:3 n-6 | 0.62 | 0.27 | 0.46 | 0.44 | 0.06 | ** | ns | ns |
C20:4 n-6 | 2.12 | 0.97 | 1.62 | 1.47 | 0.22 | * | ns | ns |
C20:5 n-3 | 0.34 | 0.15 | 0.23 | 0.26 | 0.06 | ns | ns | ns |
C22:4 n-6 | 0.22 | 0.13 | 0.18 | 0.17 | 0.02 | * | ns | ns |
C22:5 n-3 | 0.72 | 0.34 | 0.52 | 0.53 | 0.10 | * | ns | ns |
SFA | 21.65 | 27.52 | 24.82 | 24.35 | 2.19 | ns | ns | ns |
MUFA | 25.56 | 34.83 | 30.44 | 29.95 | 2.36 | * | ns | ns |
PUFA | 10.37 | 5.80 | 8.41 | 7.75 | 0.88 | * | ns | ns |
PUFA n-3 | 1.65 | 0.90 | 1.25 | 1.28 | 0.19 | * | ns | ns |
PUFA n-6 | 8.48 | 4.65 | 6.90 | 6.25 | 0.79 | * | ns | ns |
n-6/n-3 | 5.14 | 5.17 | 5.52 | 4.88 | 0.39 | ns | ns | ns |
Breed significantly affected the lipid cholesterol content with a higher level in Lm than Ma (Table
The higher weight at slaughtering and average daily gain of Ma with respect to Lm are interesting results considering that the feeding system was the same and that Lm is more specialized for beef production than Ma. These findings seem to indicate that environment factors dramatically affect the animal performance and limit the potentiality of most selected breeds. Thus, the choice of a breed for a marginal area requires a careful consideration, making the autochthonous breeds more suitable for rearing in these areas.
Due to higher muscle TL content, Ma was higher in NLs and lower in PLs than Lm. The differences in proximate composition between muscles could be due to their specific energetic metabolism. The muscle fiber metabolism was not the focus of the present experiment; however, it is well known that the energy of SM stems mainly from glycolytic pathways, while most of the TB energy is produced during the respiratory chain (
On the whole, the histological properties of muscle fibers are mainly related to the animals’ age and, in particular, younger animals show smaller muscle fibers than the older animals (
These findings are quite surprising, considering that the Lm breed has been genetically improved for beef production and it is generally considered a more precocious breed than Ma. This thus led us to hypothesize that the rearing system dramatically affected the phenotypic expression of the two breeds. The Ma breed has adapted perfectly to the climatic and pasture conditions, which, conversely, are not as easy for a non-native breed. In fact, poor summer (SU) rainfall limited the grass growth and led to low quality pasture in SU and AU, thus warranting feed supplementation. As mentioned in the Section “
The two breeds had different in TNF and CSA results, with a consequent variation in TSP. Sarcolemma has many major functions including signal transduction, membrane trafficking, and protein disposal. It contains several important lipid substances organized in a lipid raft phase [lipid ordered phase (Lo) of membrane], “immersed” in a non-raft matrix, which is a gel phase named the lipid-disordered phase—Ld (
Lipid moiety is fundamental for protein deployment, receptor activation and for triggering the signaling flux, and thus is also important for muscle contraction. Sarcolemma also comprises PLs, which contain two molecules of unsaturated long chain fatty acids, linked to a glycerol backbone by an ester bond (O-acyl bond). Thus, both the TL deposition and histological characteristics of two breeds could explain the different percentage distribution of the lipid fractions. It thus seems that the environment conditions affected not only the animal performance but also their meat quality due to the fact that the different distributions of lipid fractions, in turn, affect the total fatty acid composition. In fact, PL and NL show a specific and very different fatty acid composition. PLs are directly involved in the cell metabolism and thus are high in PUFA, which have important functions in muscle fibers. For instance, in relation to membrane functionality, the fatty acid composition of sarcolemma could affect its insulin sensitivity (
The effects on human health of these fatty acids cannot be considered separately from those of cholesterol. Cholesterol is a very important substance for the animal organism, for which there is a very effective homeostasis system (active absorption, transcriptional and posttranscription control of the synthesis, lipoprotein blood transport, membrane receptors for the transport of lipoproteins, recycling of intestinal bile salts). With respect to the cell membrane, cholesterol is a functional necessity for the formation of microdomains, which perform very important cell functions.
However, due to alterations to the homeostasis system, cholesterol can accumulate in blood vessels and promote CHD (
The lack of significance of muscle cholesterol content is a surprisingly result. In fact, as cholesterol is mainly contained in membrane cells, and due to the higher TSP in Lm, it should have been higher in Lm than in Ma. It is possible that the high TL content in the Ma breed masked the correlation between the cholesterol and sarcolemma total perimeter. On the other hand, when the cholesterol content is expressed on a TL basis, after the elimination of the effect of the TL content, the breed represents a significant variation factor (Lm showed a higher cholesterol content). In our experiment cholesterol showed a strong positive correlation with TSP (and with PL), only when it was expressed as g/100 g of TL. This led us to speculate that the muscle cholesterol content is related to TSP, but that TL and NL may hide this effect.
In conclusion, this study highlights the importance of the environment, climatic and rearing conditions in term of how they affect the full expression of the genotypic potential of a bovine breed both in relation to animal performance and meat quality. This evidence should be considered in the introduction of a bovine breed in a new area, and in the development of genetic improvement programs aimed at producing animals that are suitable for rearing in marginal areas where resources are poor.
All the experimental procedures used in this study, followed the EU guidelines for the care and use of animals in research (Italian official bulletin no. 61, 2014).
AS, GC, EG, and MM: conceived and designed the experiments. LC, CL, AB, FC, and AC: performed the experiments.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.