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    The effect of post-transport electrolyte supplementation on the dressing-out percentage of cattle, tested under commercial conditions : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology, at Massey University, Palmerston North, New Zealand
    (Massey University, 1994) Ludbrook, Roger Samuel
    The commercially used electrolyte supplement Multigro, was diluted with water and supplied to cattle as a dilute electrolyte solution. The cattle were being held in the lairage area of an export licensed meat works, and experienced normal commercial lairage conditions. The electrolyte solution was supplied to the cattle through the trough system in the lairage area. The aim of the experiment was to measure whether the cattle supplied the solution achieved a greater dressing out yield compared to cattle that were supplied water only in the lairage area. A total of 83 animals, made up of a combination of steers and bulls, were split into two treatment groups; cattle supplied water (W), (n = 41), and cattle supplied electrolyte (E), (n = 42). The cattle came from different commercial farms all within a 40 minute transportation journey of the meat plant. Two other experiments were also conducted, the first attempted to determine the water requirements of cattle in lairage. The second aimed to identify whether cattle preferred the electrolyte solution offered to water by offering both solutions to a group of cattle at the same time. The use of this electrolyte solution failed to improve the dressing-out percentage, under commercial conditions. It is suggested that the reason for this result was due to the failure of the animals to gain adequate rest while in lairage. It is further suggested that this inability to rest adequately meant that the animals never fully recovered from the influence of stressors affecting their behaviour in lairage, the result being the homeostatic control mechanism would still have been operative, assisting the animal in adjusting to its new surroundings, but not allowing its muscles to rehydrate and achieve a normal, rested, homeostatic balance.
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    Nutritional, genetic and meat quality aspects of once-bred heifer beef production systems in New Zealand : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Animal Science at Massey University
    (Massey University, 1994) Khadem, Ali-Akbar; Khadem, Ali-Akbar
    Issues related to the nutrition, management, carcass and meat quality traits, and the profitability of "Once-Bred Heifer" (OBH) beef production systems under New Zealand pastoral conditions were investigated in this research programme. Once-bred heifer beef production systems involve surplus heifers from the dairy industry which are mated to beef sire breeds at about 15 months of age and rear their calves for 3-6 months before being slaughtered at 30-32 months of age. Both the heifer dams and their progeny are thus prime meat-producing animals. The performance of once-bred v. unbred heifers and of early-weaned (EW) heifers (heifers weaned at day 84 of lactation "L84") v. normal-weaned (NW) heifers (heifers weaned at L147) were studied in the first two trials. In the third trial, Hereford x Friesian (H x F) v. Simmental x Friesian (S x F) heifers offered a restricted herbage allowance (RHA, an allowance to maintain weight) v. normal herbage allowance (NHA, an allowance to grow at 0.6-0.7 kg/d) during mid pregnancy (from pregnancy day 114, "P114", to P214) were studied in an attempt to investigate the effects of dam genotype and prior herbage allowance on the performance of heifer dams (growth rate, reproduction and carcass and meat quality traits) and their progeny (growth rate and weaning weights). A gross margin analysis was also performed to evaluate the profitability of alternative OBH beef production systems. Once-bred v. unbred Hereford x Friesian heifers consumed similar amounts of herbage organic matter (OM) during the period equivalent to late pregnancy of the former group (4.72 v. 5.15 kg OM/hd/d), but lactating heifers consumed more herbage OM than the comparable unbred group (11.36 v. 9.19 kg OM/hd/d, P < 0.05) to support the growth of their calves, as well as themselves. Unbred heifers had greater carcass weights and higher dressing-out percentages than once-bred heifers. However, the differences in other carcass and meat quality traits between the heifer groups were small, indicating that once-bred heifers are capable of producing meat comparable in quality to that of unbred and empty heifers. Higher gross margins ($5-10/Stock Unit (SU)) were calculated for once-bred v. unbred heifers. During the 10 days immediately prior to weaning, NW heifers had organic matter, dry matter and energy intakes which were slightly higher (P < 0.10) than those of EW heifers (weaned at L84). Weaning caused a slight weight loss in both early- and normal-weaned heifers for the first 30-45 days post-weaning, but liveweight (LW) was recovered after this period. During L84 - L147, EW heifers had a higher daily liveweight gain (LWG) than NW heifers (0.79 v. 0.51 kg/d, P < 0.01). Calves weaned at L84 had significantly lower daily LWG than NW calves during the period L84 - L147 (0.73 v. 1.30 kg/d, P < 0.001). This resulted in EW calves being 30 kg lighter (P < 0.001) than NW calves at the time of weaning for the latter group. Early-weaned heifers reached the target slaughter weight in March and, overall, had slightly better carcass and meat quality characteristics than those of the normal weaned group. Although similar gross margins were calculated for EW ($41.68/SU) v. NW ($42.00/SU) heifers, early weaning offers advantages to OBH beef production systems through increased flexibility of grazing management and selling times for animals. From P114 until P214, NHA heifers had significantly (P < 0.001) higher growth rates (0.72 ± 0-03 kg/d) than the RHA group (0.16 ± 0.02 kg/d). This resulted in a higher LW in NHA heifers at P214 (P < 0.001) and P270 (P < 0.01) than the RHA heifers. Gestation length, calving score, LW loss at calving and calf birth weight were not affected by dam genotype (Hereford x Friesian v. Simmental x Friesian) or prior herbage allowance. Meat quality traits were not affected by dam genotype, but it was concluded that the use of Simmental x dairy heifers in a OBH beef production system increases carcass weights of heifer dams in comparison to those of heifers derived from traditional British beef x dairy animals. However, gross margins were similar for H x F and S x F heifer groups indicating that little incentive would exist for dairy farmers to use sires of the large European breeds (e.g. Simmental) rather than Hereford sires which are commonly used to mate first-calving heifers in the dairy industry. The results are discussed in the context of the development of once-bred heifer beef production systems in New Zealand.
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    The effects of on-farm mixing of bulls on beef quality characteristics : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy at Massey University, Palmerston North, New Zealand
    (Massey University, 2010) McDade, Julie Louise; McDade, Julie Louise
    Some degree of stress is an inevitable part of the slaughter process for production animals. The degree of stress will vary due to a number of conditions over which there is sometimes no control. Stress levels may depend on such variables as familiarity of the animal to human contact and handling, temperament and even adverse weather conditions. Pre-slaughter handling has been identified as an area that can have adverse effects on both animal welfare and ultimately on meat quality characteristics. Published information on the association between stress and meat quality, and more specifically, pre-slaughter handling and meat quality is reviewed. The physiological response of an animal to stress is examined, and the effect of the stress response on the resultant final product is presented. A detailed summary of the role of muscle glycogen both pre- and post-slaughter is also provided. The main objective of the present study was to investigate whether on-farm mixing of bulls potentially plays a role in undermining meat quality characteristics Thirty-three Friesian bulls between 18 and 24 months of age and weighing between 550 and 600 kilograms (live weight) were commercially slaughtered in January of 2010. These bulls were originally from one of seven finishing groups. The bulls were randomly allocated into one of three treatment conditions 1) control (no mixing), 2) mixing four days prior to slaughter or 3) mixing one day prior to slaughter. Blood was collected at slaughter and analysed for non-esterified fatty acids (NEFA mmol/L), plasma lactate (mmol/L), creatine phosphokinase (CPK IU/L). A sample of the longissimus muscle was collected approximately 20 minutes after slaughter. A portion of the sample was immediately snap frozen for determination of muscle glycogen concentration. Meat pH, shear force and drip loss was measured at 24 hours, 7 days and 28 days post-slaughter. Purge loss was calculated for the 7 and 28 day samples. Colour measurements were taken on bloomed and unbloomed samples. By varying mixing times it was also hoped that the effect of recovery from mixing on-farm could start to be elucidated. It was a further objective that demonstration of an effect on meat quality could be used to encourage industry to adopt certain handling practices that could be communicated to their suppliers. A best practice model of pre- slaughter handling on-farm would be the ultimate goal. This project represents only a starting point from which further research would be needed prior to development of best practice guidelines. In the present study, concentrations of creatine phosphokinase (logCPK) in blood at slaughter for the 1 day mixed group was significantly higher (p < 0.001) when comparing the three treatment groups, which indicates that these animals were more physically active in the twenty four hour period prior to slaughter than the 4 day mixed or control animals. Mean CPK values for the 4 day mixed group were not significantly different from the control animals suggesting that by four days, the bulls had re-established a social order and physical activity had returned to a “normal” level. In terms of meat quality, the difference in CPK values is relevant when considering that at 28 days post slaughter, muscle tissue from the 1 day mixed bulls had increased shear force measurements (p < 0.05) when compared to the four day mixed and controls. CPK values and shear force data were found to be positively correlated in the present study (p < 0.001). CPK values were positively correlated with ultimate pH (p < 0.001) and negatively correlated with muscle glycogen concentration (p < 0.001). Although not statistically significant (p = 0.09), the pH after 28 days ageing for the meat from the 1 day mixed animals was also increased when compared to the other two treatment groups. Meat from five animals had a pH greater than 5.8 after 28 days ageing. Three of the five were from the one day mixed group while the other two were from the four day mixed group. The highest pH at 28 days was 6.14, and this one day mixed animal also had the highest CPK at 15,756 IU/l. Not surprisingly muscle glycogen concentration from the 1 day mixed animals was lower than for the other two groups, and the significance followed the same trend (p < 0.073). Results of the current study indicate that the chances of high-pH beef and the accompanying decrease in beef quality may be increased if bulls are mixed within 24 hours of slaughter. Based on the results more research into the effects of on-farm mixing is certainly warranted.