3.2.4. Chemical Composition

The chemical composition of muscles is relatively constant and includes about 75% water, 19–25% proteins, and 1–2% minerals and glycogen. The lipid fraction of muscle, however, may vary greatly between species, individuals and muscles, as well as cuts from the same animal [63,64].

The lipid fraction of muscle tends to vary highly between species, individuals, muscles, and cuts from the same animal [63,64]. Generally, *Bos taurus* types present higher marbling than *Bos indicus* breeds [65]. Examples include Brahman feedlot-fed steers, with an IMF content of 3.1%, in comparison to *Bos taurus* breeds, such as Angus (6.2%) [66,67] and Hereford (8.3%; fed forage with or without supplementation of high energy diet) [68], at similar ages and in the same muscle. Regardless of the divergence between *taurus* and *indicus*, Asian cattle breeds are known for their high IMF content [64]; Wagyu (Japanese Black cattle) and Hanwoo (Korean) feedlot steers had an IMF content of 34.3% and 13.3%, respectively, in their *longissimus thorasis* muscle [69,70].

These inter-breed differences in IMF were also demonstrated in the current study, in which the *LL* muscles of Holstein calves exhibited higher IMF content than those of their Australian counterparts (*p* = 0.002; Table 3). These findings are not surprising in light of the reported comparative marbling physiology, referring to the greater proportion of the marbling fleck area and number of marbling flecks of Holstein beef, at a similar slaughter age—12 months—to that reported here, even in comparison to typical beef breeds [67]. With respect to the positive effects of IMF on meat organoleptic characteristics, such as flavor, juiciness and tenderness, firmness, and overall acceptability by consumers [71], the findings presented herein rank the local breed in an advantageous position to satisfy consumers' sensory choices [16].

**Table 3.** Effects of farm and breed on proximate composition of meat from Holstein (HOL) and Australian (AUS) male calves. Farm 1 (F1; HOL; N = 62); Farm 2 (F2; HOL; N = 143); Farm 3 (F3; AUS; N = 169).


Different lower case letters indicate significant differences between the two breeds for each measurement (*p* < 0.01).

#### *3.3. Characteristics of Meat Tenderness: Shear Force, Sarcomere Length and Total Collagen*

Tenderness is the most important sensory attribute by which consumers judge the quality of their meat [16]. It is a variable phenotype, mostly influenced by genetic factors, muscle characteristics at slaughter [72], or post-mortem changes induced by ageing [16]. Indeed, inconsistency in meat tenderness is considered a major obstacle facing the beef production industry [73]. The phenotyping of tenderness is performed via sensorial panel testing or instrumental measurements [74], but most often the two are conducted in parallel, and correlations between them are determined [75].

In our study, tenderness, evaluated instrumentally, was significantly higher in the meat of Holstein calves, as judged by the lower SF values, statistically adjusted to the farm and breed effects (41.5 ± 9.66 N vs. 46.5 ± 9.27 N, respectively; *p* < 0.0001; Table 4). Differences in meat tenderness among *Bos taurus* and *Bos indicus* breeds, with the advantage held by the former, are well documented [76]. This phenomenon mostly stems from genetic variations in the gene encoding the calpastatin proteolytic enzyme, which are found in association with the rate and extent of muscle proteolysis postmortem [76–79]. Both the calpastatin's rate of activity and meat tenderness are moderately-to-highly-inheritable, and genetically correlated [78,80].

**Table 4.** Effects of farm and breed on tenderness characteristics of the *longissimus lumborum* (*LL*) muscle of Holstein (HOL) and Australian (AUS) male calves. Farm 1 (F1; HOL; N = 62); Farm 2 (F2; HOL; N = 143); Farm 3 (F3; AUS; N = 169).


Different lower case letters indicate significant differences between the two breeds for each measurement (*p* < 0.0001).

A comparative analysis of the meat quality characteristics among 15 muscles categorized *LL* as one of the most tender (WBSF < 35 N) muscles in Holstein male calves [4], making it a legitimate target for inter-breed comparisons. Accordingly, and based on tenderness classification, established upon the relationship between instrumental measurements and consumer perception [73], the *LL* muscle of the Holstein calves in the current study, may be ranked as tender, while that of Australian may be ranked as intermediate. Similarly, other studies of Holstein animals observed relatively high tenderness in the same muscle [4,16].

Moreover, a comparison between the meat quality characteristics of Holstein and Salers (dual breed, often used for beef) cull cows, following 14 days of ageing, did not reveal differences in sensory qualities, such as tenderness and juiciness [16]. These findings, which are in agreement with Monso'n, et al. [81], indicate that by applying the ageing process to local Holstein meat, its organoleptic characteristics may be improved beyond their genetic potential.

Another attribute of meat tenderness is SL. It is often used as a post-rigor indicator [82], representing a positive association with meat tenderness and WHC [83]. In our study, SL differed significantly (*p* < 0.0001) between the two breeds (Table 4). When the farm effect was studied, longer sarcomeres were measured in the muscles of Holstein calves from both farms (2.22 ± 0.30 μM and 2.10 ± 0.27 μM, respectively), compared to the SL of Australian calves from F3 (1.98 ± 0.32 μM; *p* < 0.0001).

Total collagen content is a key parameter for the evaluation of meat tenderness [84]. The increase in the stability of cross-linking between collagen molecules, which is determined by growth rate, nutrition and genetics [84], affects the toughness of meat [85]. Studies in cattle have shown a large variation in the content of collagen, which differs between muscles, breeds, and animals of different ages. No differences in the content of total collagen were found in the current study, between farms or breeds. The values ranged between 2.70 ± 0.83–2.88 ± 0.64 mg/g (Table 4), and were comparable to or lower than those in other breeds [86,87], including Holstein, that were exclusively reared on grass pasture [88]. The lower amounts of total collagen reported herein might have resulted from the relatively younger age of the calves (~12 months). Indeed, the proportion of maturity to reducible crosslinks increases with age, resulting in less tender meat in older animals [89]. Nevertheless, Archile-Contreras et al. [90] suggested that variations in collagen turnover might be affected by the position of the muscle in the animal's body and could, therefore, influence meat tenderness. Accordingly, less positional muscles, such as the *longissimus dorsi*, are characterized by reduced collagen concentrations and cross-links, and therefore, produce tenderer meat compared to locomotive muscles, such as *semimembranosus* (SM) [91].

#### *3.4. Fatty Acid Composition*

The nutritional, health and sensory qualities of meat are, to a great extent, determined by its FA composition, which is influenced by various factors, such as diet, breed, age and the level of fat content in the muscle [92]. With respect to their nutritional significance, the fact that meat is a major source of dietary SFA, which is implicated in diseases associated with modern life [93], has triggered increased interest in ways of manipulating the FA composition of meat. In particular, efforts have been made to increase the dietary ratio of polyunsaturated fatty acids (PUFA) to SFA to above 0.4, and to decrease the ratio of n-6:n-3 (i.e., alpha-linolenic to linoleic acid) PUFA to less than 4 [93]. In spite of some clear effects of diet on the FA composition of tissues [94], a combination of bovine genetic background and dietary manipulation could favor particular FAs [95].

In the current study, we estimated the effects of farm and breed on the profile of FA in the *LL* muscle of Holstein and Australian calves. The proportions of short chain saturated FAs, including capric (C:10; *p* = 0.0012), lauric (C12:0; *p* < 0.0001), myristic (C14:0; *p* = 0.0002), pentadecanoic (C15:0; *p* < 0.0001), palmitic (C16:0; *p* = 0.0052) and heptadecanoic (C17:0; *p* < 0.0001) acids, were significantly higher in the fat of Australian calves, when the breed effect was studied (Table 5). Surprisingly, in spite of the improved meat tenderness of Holstein calves (Table 4), the proportion of their stearic acid (C18:0) was significantly higher (*p* = 0.0008) (Table 5). Stearic acid is indeed known for its high and positive correlation with the melting point of fat, which in turn reflects the firmness of meat. However, the best prediction of firmness was provided by the ratio of stearic acid to linoleic acid (18:0:18:2) [93], which in the present study was lower for the Holstein calves (3.15 ± 0.86 vs. 3.97 ± 1.07; *p* < 0.0001). The total proportion of mono-unsaturated FAs (MUFAs) did not differ between breeds (Table 5). However, while oleic (C18:1n9c; *p* = 0.0261) and C18:1n10c (*p* = 0.016) FA were higher in the meat of Australian calves, vaccenic (C18:1n11c; <0.0001) and C18:1n12c (*p* < 0.0001) FAs were higher in the meat

of Holstein calves (Table 5). Vaccenic acid is formed in the rumen as a result of partial bio-hydrogenation, and is a precursor for tissue-conjugated linoleic acid (CLA), a wellrecognized, health-promoting FA [96], whose proportions as observed in this study were not in favor of the Holstein calves, presumably due to breed-specific differences in the activity of tissue stearoyl CoA desaturase (SCD). Unlike CLA, the total proportion of PUFA was significantly higher in the *LL* muscle of the Holstein calves (*p* < 0.0001). Specifically, higher proportions were revealed for linolelaidic (C18:2n6t; *p* < 0.001), linoleic (C18:2n6c; *p* < 0.0001), α-linolenic (C18:3n3; *p* = 0.0015), Eicosatrienoic (C20:3n6; *p* < 0.0015) and arachidonic (C20:4n6; *p* = 0.0047) acids (Table 5).

**Table 5.** Proportion of fatty acids in the *longissimus dorsi et lumborum (LL)* muscle of Holstein (HOL N = 110) and Australian (AUS; N = 100) calves.


FA: Fatty Acid; SFA: saturated fatty acids; MUFA: mono unsaturated fatty acids; PUFA: polyunsaturated fatty acids; S.D: standard deviation.

PUFAs are known to possess anticarcinogenic and hypolipidemic properties [97], and to act as modulators of different transcription factors, providing, at least partially, the metabolic link between dietary PUFA intake, health, and the progression of chronic diseases [98]. However, taking into account the health-promoting capacity of PUFA and the deleterious dietary potential of SFA, nutritionists have suggested that the desired ratio of PUFA to SFA should exceed 0.4, while in some meats, naturally, it is around 0.1 [93]. While

in accordance with this notion, the PUFA-to-SFA ratio reported herein again highlights the superiority of local Holstein over imported Australian meat (*p* < 0.0001; Table 5).

#### **4. Conclusions**

In summary, from a scientific perspective, the present study provides an understanding of the 'beefy' qualities of the dairy Israeli Holstein, via the characterization of the organoleptic, physical and technological properties of its meat. Aiming to lay the foundations for sustainable beef production system in Israel, the current study evaluated the comparative potential of local Israeli Holstein and genetically mixed *Bos indicus* X *Bos taurus* calves, imported from Australia, to produce qualitatively fresh meat. It was found that the meat produced by the local breed was superior according to quality- and health-related characteristics. Specifically, while the Australian calves demonstrated a superior dressing percentage, the Holstein meat was characterized by higher tenderness, greater IMF content, longer sarcomeres, improved PUFA-to-SFA ratio (Figure 1) and superior technological parameters of raw and thermally treated meat.

**Figure 1.** An illustrative violin plot of production (dressing percentage; DP) and meat quality characteristics (shear force, SF; sarcomere length, SL; intra-muscular fat content, IMF; polyunsaturated-to-saturated fatty acid ratio, P/S), comparatively evaluated in Holstein (green; HOL) and Australian (pink; AUS) male calves. The values of each trait are normalized (0,1). Green and yellow dots with dashed lines indicate the mean value of each variable, for Holstein and Australian plots, respectively. The two box plots outlined in blue differentiate between the advantages in production of AUS (left) and meat quality of HOL (quality; right) characteristics.

The results presented herein may provide sound arguments for stakeholders and policy makers to facilitate sustainable local beef production in Israel. Once implemented, such production may comply with the 'farm-to-fork' approach by emphasizing potential motives, such as improved animal welfare, traceable, transparent and shorter supply chains, positive environmental impact, the production of nutritious, healthy, safe and sufficient foods, and fairer economic returns for primary producers.

In a broader sense, the current study may serve as an example of how the 'farm-to-fork' approach may also be implemented in other parts of the world. In developing countries, for instance, fulfilling the productive potential of imported animals depends upon favorable but unsustainable conditions. Hence, adjusting to an integrative model for sustainable indigenous breed production, which is based on their economic and biological efficiencies, might orient local food systems towards a positive environmental impact, improved product quality and animal health and welfare. Moreover, it may enable smallholder

farmers to maintain their animals in the long run, and provide an income for poor farmers while maintaining their cultural identity.

**Author Contributions:** Conceptualization and methodology, A.S. and M.C.-Z.; formal analyses, A.O., R.A., E.S.-S. and O.T. (Olena Trofimyuk and Ofir Tal); validation, A.S. and M.C.-Z.; resources, A.S. and M.C.-Z.; writing, review and editing, A.S. and M.C.-Z. All authors have read and agreed to the published version of the manuscript.

**Funding:** This study was supported by the Israeli Chief Scientist, Ministry of Agriculture, Project # 362-0486-16, and by the Israeli Dairy Board Foundation, Project #.362-0457-16.

**Institutional Review Board Statement:** Ethical review and approval were waived for this study, since it did not involve living animals; meat cuts (steaks) and relevant data on carcass and live weight performances were provided by Bakar Tnuva Ltd, Beit Shean, Israel.

**Informed Consent Statement:** Research does not involve human studies.

**Data Availability Statement:** The current study does not report any supporting data.

**Acknowledgments:** We thank Wassim Geraisy, the Chief Veterinarian in "Bakar Tnuva Ltd." abattoir for his collaboration, which enabled to obtain meat samples, and Ido Izhaki, for his assistance in the statistical analyses.

**Conflicts of Interest:** The authors declare no conflict of interest.

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