Farm to abattoir conditions and their subsequent effects on behavioural and physiological changes and the quality of beef from extensively-reared Nguni and non-descript steers
- Authors: Njisane, Yonela Zifikile
- Date: 2016
- Subjects: Nguni cattle Beef cattle breeds Beef -- Quality -- South Africa , Slaughtering and slaughter-houses -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/3143 , vital:28324
- Description: The main objective of the study was to determine the effect of farm to abattoir environmental conditions and their subsequent effects on behavioural and physiological responses, as well as the quality of meat from Nguni (NG) and non-descript (ND) beef steers reared extensively on natural pastures. The forty 16 – 19 months old steers (20 ND and 20 NG) used in the current study were grouped together, medically treated, allowed three weeks acclimatizing period and were used in this trial over a four-month period. The weather and periodical variations influence on time budgets and body weights of these steers were determined. Furthermore, the effects of on-farm successive handling on behavioural scores and physiological responses of the same steers were determined. Later in the trial, some pre-slaughter effects on response-behaviour, bleed-out times and selected blood physiological responses were determined. Finally, the effect of genotype, muscle type, lairage duration, slaughter order and stress responsiveness on pH24, temperature, colour (L*, a*, b*, C, HA), thawing (TL) and cooking (CL) losses and Warner Bratzler Shear Force (WBSF) of the meat harvested from the same steers were determined. The daily time budgets of steers in natural pastures changed with temperature, humidity, observation week and time of the day. The grazing behaviour was observed throughout the observation days (> 37 percent); though it was reduced (26.9±2.64 percent) on days with higher temperatures and low humidity. Higher proportions of drinking (1.5±1.04 percent) and standing (20.8±4.63 percent) behaviours prolonged in such weather conditions, which were mostly during midday. The avoidance-related behaviour of the steers during handling varies, with the steers showing more avoidance and aggression in other weeks than some. These variations could however be traced back to the events of that particular day/time of handling. Only Weighing Box (WBS) and stepping (SS) scores differed (P<0.05) with genotype; with more calm NG steers (> 40 percent) and not kicking than the ND steers that were more vocal (20–60 percent) and kicking (> 5 percent). In addition, the weekly behavioural responses were reflected (P<0.05) in the measured cortisol, glucose and lactate. However, regardless of the prominent negative behaviour seen over time, the levels of the measured blood constituents continued to drop. Furthermore, steers of different genotypes displayed similar (P>0.05) response to the identical pre-slaughter conditions they were exposed to. However, steers that were Transport Group 1 (TG1) showed more avoidance (63.2 percent) pre-slaughter than those in TG2 (23.9 percent). Furthermore, all the steers that were in slaughter Group 2 (SG2) showed less avoidance behaviour than those in other groups. Vocalization was observed only for ND steers (5 percent), in TG1 and SG2. Some connections between the observed pre-slaughter activities and some behavioural and physiological changes of these steers were established; with TG1 and SG1 steers showing higher cortisol (140±14.50 and 175.9±17.24 nmol/L, respectively) and lactate (12.4±0.83 and 13.5±1.12 mmolL) levels than the other groups. Lastly, the muscle type, genotype, lairage duration, slaughter order and stress responsiveness have an effect on some meat quality characteristics of the two genotypes; with the L. dorsi muscle having highest WBSF (38.0±1.35N) than the Superficial pectoral muscle (Brisket muscle) (30.7±1.35N). Additionally, steers lairaged for a shorter time produced a L. dorsi with higher WBSF (41.6±2.34N) and a Brisket with lower TL (2.7±0.24 percent). It can therefore be concluded that the conditions and activities at the farm, during transportation, lairaging and slaughter at the abattoir have an influence on some behavioural and physiological changes and the quality of beef harvested from the Nguni and non-descript steers that were extensively-reared in natural pastures. However, the relationship patterns between these different conditions are not clear.
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- Date Issued: 2016
Avoidance-related behaviour, bleeding times and the quality of meat from sheep slaughtered at a commercial and a municipal abattoir
- Authors: Njisane, Yonela Zifikile
- Date: 2012
- Subjects: Mutton -- Quality , Sheep -- Quality , Slaughtering and slaughter-houses -- South Africa , Animal behavior , Dorper sheep , Meat -- Quality , Sheep -- Carcasses -- Handling
- Language: English
- Type: Thesis , Masters , MSc Agric (Animal Science)
- Identifier: vital:11818 , http://hdl.handle.net/10353/d1004195 , Mutton -- Quality , Sheep -- Quality , Slaughtering and slaughter-houses -- South Africa , Animal behavior , Dorper sheep , Meat -- Quality , Sheep -- Carcasses -- Handling
- Description: The objective of the study was to determine the avoidance-related behaviour, bleeding times and the quality of meat from sheep of different gender, breed (Dorper, Merino, and their crosses) and age groups, slaughtered at a commercial and municipal abattoir. Castrates and ewes of different age groups (1= <10months, 2= 11-12months, and 3= >12months) and breeds were used. From the commercial abattoir, 90 castrates and 110 ewes were used, while 66 castrates and 19 ewes were obtained from the municipal abattoir. Meat samples were obtained to determine meat colour, ultimate pH, temperature, cooking loss and tenderness. Correlations between bleeding times and meat quality variables were also determined. The two abattoirs differed in terms of technology and the procedures used, and this brought about different response behaviours in sheep at slaughter, bleeding times at exsanguination and the quality of meat produced. Animal-related factors (breed, gender and age classes) had no effect on the avoidance-related behaviour of sheep slaughtered at the commercial abattoir, while these factors affected those sheep slaughtered at the municipal abattoir. These factors also had an effect on the quality of meat produced at both abattoirs. Gender and weight of the animals had effects on the bleeding times at exsanguination at both abattoirs. Bleeding times did no correlate with any of the meat quality variables, but correlations among meat quality variables were observed. Avoidance-related behaviour, bleeding times, and the quality of mutton from sheep slaughtered at a commercial and a municipal abattoir was affected by breed, age, and gender.
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- Date Issued: 2012