Physiochemical parameters
The physicochemical properties of Salem black goat meat are presented in Table 1. The pH values for
longissimus dorsi muscle were higher at 9 months slaughter compared to 6 months. Male animals had slightly higher pH values than females and the system of management did not influence these values. These values were similar to previous reports of
Hussin et al., (2000) and Werdi
Pratiwi et al., (2004a). In agreement with
Enfalt et al., (1997), the trend of higher the pH lesser in extract release volume and more in water holding capacity of meat was observed in the present study.
Fresh meat colour is an important criterion for judging freshness and quality by consumers. Muscle colour is darker red, (a* values) for muscle taken from kids slaughtered at 9 months compared to 6 months. Lightness (L*) and yellowness (b*) values decreased as the animals got older and heavier in the present study. The results confirm the reports of Werdi
Pratiwi et al., (2004a) who observed that the colour of
longissimus dorsi muscle become darker red with age, as muscle pigment concentration increases. This is because muscle colour is greatly influenced by the concentration and chemical nature of haemoprotein present in the muscle
(Kannan et al., 2001). System of management and sex of the animal did not influence the colour of the meat.
Mean fibre diameter of Salem Black goat meat ranged from 33.51 to 38.54 µm. Higher muscle fibre diameter was observed in semi-intensive system compared to intensive system of management in the present study might be due to exercise by extensive movement during grazing. Furthermore, it was evident that with the increase in the age, the mean fibre diameter value also increased, which was in concurrence with the result of
Ilavarasan et al., (2018). The muscle fibre diameter can be positively correlated with shear force value and negatively with tenderness and sarcomere length
(Kandeepan et al., 2009). The measured fibre diameter for Salem Black goat was higher than two and half year old Black Bengal goats (29.94 µm) and Garole sheep (26.64 µm) (
Kesava Rao et al., 1984) and comparable with Sudan desert sheep (32.5µm) (
Gaili and Ali 1985a) and, Muzaffarnagari rams (37.91µm) (
Kesava Rao et al., 1998).
Sarcomere length plays a key role in the development of meat tenderness and it may provide useful information for economic production of farm animals to produce high quality meat. The result of the present experiment showed that sarcomere length significantly (P<0.01) decreases with advancing age. The variation in sarcomere length and their interaction with proteins released during collagen proteolysis directly determines the tenderness of individual muscle (
Wheeler and Koohmaraie, 1999).
Devine et al., (1993) reported that the tender meat will have the SFV varied from 5.53 to 7.24 kg/cm
2. In accordance with earlier study, male goats and slaughtered at 9 months old age produced significantly (P<0.05) tender meat compared to female and 6 months groups. Variations found in the SFV can be attributed to differences in nutrition, age and final meat pH
(Devine et al., 1993).
Collagen content was significantly (P<0.01) higher in meat for intensively reared animal compared to semi- intensively reared animal. Similarly, the sex and age of the animal significantly influences the collagen content of the meat. Male kid meat had higher collagen than female. The collagen content was increased with increasing age in the present study. The higher collagen content can be attributed due to the age of the animals, greater amount of soluble, less stable collagen with fewer covalent cross- links between the collagen (
Argüello et al., 2005).
Proximate composition
The meat from kids reared under intensive system of management had significantly (P<0.05) lower moisture, higher ether extract and energy as compared to semi-intensively reared kids in both the age groups (6 and 9 months) (Table 2) which were in accordance with the findings of
Pal et al., (1997) and
Dass et al., (2008) in Muzaffarnagari lambs. The higher feed intake, better nutrient utilization and restricted movement might have lead to more fat deposition resulting higher ether extract and energy values in meat of intensively reared kids compared to semi-intensively reared kids in the present study. Higher fat content decreased the moisture content in meat as fat accumulation in muscle tissue replaces water under adequate feeding
(Dass et al., 2008, Rajkumar and Agnihotri, 2005). The ether extract and gross energy content of the
longissimus dorsi muscle were lower than those found by
Babiker et al., (1990) for goats slaughtered at 35 kg live weight and maintained under complete diet.
Sex of the animal significantly (P<0.01) effected the ether extract and acid insoluble acid content of the meat. Females had higher percentage of ether extract in
longissimus dorsi muscle than males. The result can be attributed to differences in the growth and development between females and males resulting from sexual hormone effects that influence growth speed and animal tissue components deposition (muscle, fat and bone). Moisture has shown an inverse relationship on the fat content of meat which is in agreement with findings of
Sheridan et al., (2003) (Boer Goat Kids) and
Santos et al., (2008) (Portuguese native breed).
The crude protein, ether extract, calcium, phosphorus salt, gross energy content of the muscle were significantly (P<0.01) higher in meat of 9 months old goats as compared to 6 months. The moisture percent was significantly (P<0.01) lower due to increased protein and fat percentage during growth period. This is similar to the findings of
Dass et al., (2008). In Contrast,
Sivakumar et al., (2013) reported no significant difference between the weight groups 12-15 and 15 -18 kg for proximate principles of the meat in Kanniadu. The variation might be due to the difference in age, feed and breed of the animals
(Mahgoub et al., 2002).
Fatty acid composition
The Palmimic, Palmitolic, Linoleic, Stearic acid and DHA were significantly (P<0.01) higher in intensively reared kids meat compared to semi-intensively reared kids (Table 3). The greater concentration of these fatty acids observed in intensive system may be due to the greater consumption of nutrients
(Lopes et al., 2014). Similarly,
Jenkins et al., (2008) reported that the greater amount of starch consumed by goats fed
ad libitum favours the development of protozoa which are an important source of PUFA and CLA in the meat. Sex of the animal did not significantly (P>0.05) influence the fatty acid composition of the meat in the present study. However,
Johnson et al., (1995) and
Matsuoka et al., (1997) reported lower total muscle lipids and greater PUFA: SFA ratio in male animals compared to female animals and similar concentrations of PUFA in Japanese Sannan goats between male and female. Literature review reveals that differences in fatty acid composition due to sex have been inconsistent. Studies of
Terrel et al., (1968) with cattle have shown that sex effects were associated with the neutral rather than phospholipid fraction of fatty acids. The results of
Matsuoka et al., (1997) for Japanese Jackson goats shows that sex difference in fatty acids composition are more pronounced in phospholipids than in neutral lipids. In accordance to
Banskalieva et al., (2000), Salam Black goat meat contains lower concentration of other fatty acids (Eg. C20:0, C12:0, C15:0, C17:0, C20:1, C20:3, C22:0, C24:0, C22:4 and C22:6).
Management system significantly (P<0.01) influences the SFA, MUFA, PUFA and PUFA: SFA ratios and age of the animal influence the MUFA content of the muscle were observed in the present study (Table 4).
The intensively reared kids had significantly (P<0.01) lower concentrations of SFA, greater concentrations of MUFA and PUFA and PUFA: SFA ratio compared to other rearing system. It may be attributed due to high plan of nutrition which produced more fatty acids through de novo synthesis (mainly oleic acid)
(Lopes et al., 2014) and the increased intramuscular fat content in the
longissimus dorsi muscle (
De Smet et al., 2004). However, meat from 6 months slaughter had significantly higher (P<0.05) MUFA level compared to 9 month slaughter others did not differ related to age of the animal.
Longissimus dorsi muscle from Salem Black goat contain higher unsaturated, monounsaturated and polyunsaturated fatty acids and which are considered desirable fatty acids that have either a neutral or cholesterol lowering effect.