@conference {41169,
	title = {Involvement of calpains in postmortem tenderisation: A review of recent research},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {60},
	year = {2000},
	month = {Jan},
	pages = {99-102},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {Tenderness is an important determinant of meat quality. Inconsistency and variability in tenderness have been identified as major problems for the meat industry (Morgan et al., 1991). It is well documented that tenderness improves during postmortem storage of meat but the mechanisms involved remain controversial. The general consensus is that proteolysis of structural muscle proteins causes tenderisation but alternative theories suggest that changes in the actin-myosin interaction (Goll et al., 1997) or a non-enzymatic effect of calcium on muscle proteins (Takahasi, 1999) or a rise in ionic strength (Ouali, 1990) may be involved. However, discussion of these theories is not within the scope of this review. With regard to postmortem proteolysis, the calpain system is thought to play a major role. Calpains are calcium-activated proteases with an optimum activity at neutral pH. In skeletal muscle, the calpain system consists three proteases, m-calpain, m-calpain and skeletal muscle-specific calpain, p94, and an inhibitor of m- and m-calpain, calpastatin. The involvement of calpains in postmortem tenderisation has been the subject of several reviews (Goll et al., 1991; Koohmaraie, 1988, 1992a, 1994, 1996; Ouali, 1990). Since these reviews, new information has become available which has provided answers to some of the questions on the role of calpains in postmortem tenderisation. The purpose of this review is to discuss some of these issues in the context of recent results. For further information on postmortem proteolysis and meat tenderness, or characteristics of the calpain system, the reader is referred to a number of excellent reviews (Penny, 1980; Greaser, 1986; Croall and DeMartino, 1991; Ouali, 1992; Sorimachi et al., 1994; Ono et al., 1998). },
	issn = {1176-5283},
	author = {Geesink GH and Ilian MA and Morton JD and Bickerstaffe R}
}
@conference {41137,
	title = {Marker-assisted Selection for Meat Quality and the Ovine Calpastatin Gene},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {59},
	year = {1999},
	month = {Jan},
	pages = {266-268},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {The calpain-calpastatin system (CCS) comprises a family of calcium-dependent neutral proteases, the calpains, and calpastatin, a specific inhibitor of the calpains that regulates their activity in vivo. The CCS is found in most animal tissues and influences many important processes including muscle development and degeneration, meat tenderisation postmortem, cataract formation and fertility. The calpains have been shown to play the major role in postmortem tenderisation in beef, lamb and pork by degrading specific muscle structural proteins. The level of calpastatin immediately postmortem appears critical in determining the ultimate tenderness of aging muscles. Tenderness has been shown in consumer surveys and tasting panel tests to be the most important characteristic determining the overall eating quality of meat. In using a molecular genetic approach to studying meat quality in sheep we have chosen the ovine calpastatin gene (CAST) as a candidate gene for meat quality. We have described a three allele system of polymorphic variants (CAST a, b and c) in a region of the ovine CAST. Since 1995 we have carried out slaughter trials on small groups of Dorset Down hoggets and Dorset Down x Coopworth lambs to ascertain any association between meat quality traits and the molecular markers in CAST. Sheep with the genotypes of CAST aa, ab and ac were compared. These trials indicate an association of the CAST genotype ac with increased liveweight gain (+12-17\%,p >0.05), increased age-corrected carcass weight (+15-18\%, p>0.05), but also increased longissimus dorsi shear force (+4-12\%, nonsignificant) compared to sheep with the CAST genotype aa. },
	issn = {1176-5283},
	author = {Palmer BR and Morton JD and Roberts N and Ilian MA and Bickerstaffe R}
}
@conference {41012,
	title = {Calpain and calpastatin activity in muscle from genetic lines of lambs selected for divergent levels of fatness.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {143-145},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {There is widespread interest in the extent to which genetic factors influence meat quality. In this study we examined meat quality characteristics and the activity of the calpain protease system in M. longissimus lumborum (LL) from backfat selection lines of Southdown lambs. The high fat line produced heavier carcasses with greater soft tissue depth GR. LL from the high fat line animals had a lower ultimate pH and was significantly more tender at 24h post-mortem using the MIRINZ tenderometer but not the Warner-Bratzler peak force. There was a decline in m-calpain and calpastatin activity but not m-calpain in the 9h post-mortem. There were no significant differences in the levels of the calpains or their inhibitor between high and low backfat lines. However, when the results were adjusted for pH, the 20 min calpastatin levels were highest for the sire group that had the highest peak force value. },
	issn = {1176-5283},
	author = {Morton JD and Bickerstaffe R and Purchas RW}
}
@conference {40965,
	title = {A candidate gene approach to animal quality traits.},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {57},
	year = {1997},
	month = {Jan},
	pages = {294-296},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {A variety of animal quality traits, particularly those associated with meat and wool production and disease resistance, have been the subject of sophisticated genetic analyses. Investigation of the biochemistry and physiology underlying disease or production traits has implicated particular proteins and hence genes as "candidates" for having major phenotypic effects. This makes the candidate gene approach a useful complement to animal genome mapping of markers and QTLs. We have applied the candidate gene approach for the sheep quality traits of meat tenderness and footrot resistance. A three allele system detected by polymerase chain reaction - single strand conformational polymorphism (PCR-SSCP) has been observed for the ovine calpastatin gene. Calpastatin is the specific inhibitor of the ubiquitous calcium-dependent proteases u-calpain and m-calpain. There is very strong population genetic and protein assay data in cattle to inversely correlate post-mortem calpastatin levels with meat tenderness. Assay of post-mortem calpastatin levels in aging lamb confirms an important regulatory role for calpastatin in sheep meat aging. Data sets from preliminary experiments testing the association of the three allele ovine calpastatin system with meat tenderness values and other meat quality characteristics show significantly different fillet tenderness, early post-mortem calpastatin and u-calpain levels between ewes with different calpastatin genotypes. The early post-mortem calpastatin levels and the longissimus dorsi pH at 24 hr post-mortem of sheep representing two different genotypes was also significantly different. The major histocompatibility (MHC) proteins of vertebrates have a role in presenting peptide fragments from pathogenic organisms to the systemic immune system. It is hypothesised that a component of resistance in sheep to footrot is based on an effective systemic immune response and hence controlled by MHC presentation. Sixteen alleles have been identified at the ovine MHC class II DQA2 locus and 8 at the DQA1 locus. A significant (p=0.001) association between footrot status and DQA2 genotype was observed in a halfsib family challenged with the disease under standardised field conditions. },
	issn = {1176-5283},
	author = {Palmer BR and Hickford JGH and Bickerstaffe R}
}
@conference {40885,
	title = {Growing wool in tissue culture - which sheep breed is best?},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {57},
	year = {1997},
	month = {Jan},
	pages = {48-50},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Individual wool follicles were isolated from adult sheep and maintained in tissue culture for three days. Follicles from Merino, Poll Dorset and Suffolk animals were classified as fine wool types and were compared with follicles from Romney, English Leicester and Drysdale animals which were termed a coarser wool type. There were significant differences in both follicle survival and the rate of fibre growth between coarse and fine follicle types maintained in vitro. Only 48\% of follicles from animals with fine fibre types survived in tissue culture. In contrast, 84\% of follicles from coarse fibre types remained viable in vitro (P<0.01). The fibre growth rates of viable follicles was also significantly different between fibre types (P<0.01). Follicles isolated from animals classified as fine fibre types had a fibre growth rate of 108 {\textpm} 16um per day compared with 170 {\textpm} 12um per day fibre growth by animals with coarser fibre types. In vitro fibre growth by animals with large, straight follicles such as those from the English Leicester and Drysdale animals was greatest and a high proportion remained viable. Furthermore, follicles from these animals were easy to isolate relative to finer fibre types. Dissection of finer follicles was considerably more difficult, due to the decreased follicle size, curvature and high follicle density; factors which may be responsible for their reduced viability in vitro. },
	issn = {1176-5283},
	author = {Winder LM and Scobie DR and Bickerstaffe R}
}
@conference {40804,
	title = {Proteases and meat quality},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {56},
	year = {1996},
	month = {Jan},
	pages = {153-156},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Consumers judge the quality of meat at the point of sale on colour, visible fat content and odour. However, on eating meat, characteristics such as juiciness, flavour and texture also assume importance. Supermarket surveys of customer preferences have indicated that tenderness is the single most important meat quality characteristic that in-fluences whether consumers are repeat buyers. In New Zealand, the industry standard for tenderness is that shear force must be less than 11 kg F for exported meat. The meat industry recognises, however, that 11 kg F is the upper limit for shear force and that for discerning markets, tenderness values of <5 kg F are required if the markets are to be retained or improved.},
	issn = {1176-5283},
	author = {Bickerstaffe R}
}
@conference {40536,
	title = {Impact of pre- and post-mortem factors on calpains and meat quality in lambs},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {53},
	year = {1993},
	month = {Jan},
	pages = {403-406},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Increased thymic weights have been reported in sheep selected for  resistance to internal parasites and treatment with IGF-1 increases thymic and  splenic weights in sheep, suggesting that IGF-1 may have a role in regulating  immune function. This hypothesis was examined in four experiments using  mice as a model. Expt 1 Unselected Swiss mice (n-24) were injected 2 x daily  with 30 mg/d rhIGF-1 or saline for 26 days from 28 days of age. IGF-1  treatment increased spleen weight at a common body weight (118.2 vs 95.9,  pooled standard error (PSE) = 6.2 mg, P<0.05), but did not affect thymic  regression (thymic weights at the end of treatment: 85.5 vs 81.9, PSE = 4.0  mg). Expt 2 Unselected female Swiss mice (n=22, age = 84.8},
	issn = {1176-5283},
	author = {Sun YX and Bickerstaffe R and Bray AR and Keeley G and Young S and O{\textquoteright}Connell D and Mason S}
}
@conference {40374,
	title = {Lambs selected for fast glucose clearance have high meat pH levels when stressed before slaughter},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {52},
	year = {1992},
	month = {Jan},
	pages = {49-52},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Two groups of 10 intact Border Leicester ram lambs (10 weeks  old; 22.7},
	issn = {1176-5283},
	author = {Bray AR and Francis SM and O{\textquoteright}Connell D and Bickerstaffe R}
}
@conference {40202,
	title = {Characterisation of the insulin status of lambs and consequences for carcass composition},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {50},
	year = {1990},
	month = {Jan},
	pages = {97-100},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {As part of the study into the mechanism by which nutrition   influences ovulation rate two trials have been conducted to examine the   effect of protein intake on the negative feedback of oestradiol-17Beta   (E17Beta) on plasma FSH levels. In Trial 1 three groups of   ovariectomised ewes (n=8) fed on a low protein (LP 11\%, 10 MJ ME) diet   were treated with silastic implants of E17Beta. Four days after implant   insertion one group was changed to a high protein (HP 22\%) diet while   another was treated orally for 10 days with phenobarbital (1 g/d). The   E17Beta implants were removed 6 days after treatment started. In Trial 2   groups of ewes (n=6) were given either full (HE) or 1/2 size (LE)   implants for 5 days. All ewes were fed on a LP diet but 2 groups were   infused abomasally with 100g/d of protein (HP) commencing 3 days before   implant. FSH levels were monitored 4 x d throughout both trials and   expressed as a percentage of pre-treatment values. In Trial 1 FSH   levels were 33\% on day 11 after implant with no treatment difference.   However after implant removal the values for the LP ewes returned to   100\% by day 17 while for the HP and phenobarbital group values remained   at 33\%. In Trial 2 the levels 4 days after implant insertion were 37\%,   and 48\% for the HE and LE ewes. Again protein treatment delayed   recovery following implant removal. These results do not support the   hypothesis that the increased ovulation rate following protein   supplementation is due to a reduction in negative steroid feedback on   FSH levels.    },
	issn = {1176-5283},
	author = {Willis JA and Bickerstaffe R and Munro JM and O{\textquoteright}Connell D}
}
@conference {40201,
	title = {The insulin status of sheep with genetic differences in glucose tolerance and carcass composition},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {50},
	year = {1990},
	month = {Jan},
	pages = {93-96},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Twenty four Coopworth ewes, selected on the basis of an   increased ovarian response to lupin grain supplementation, were   ovariectomised and fitted with a Foley catheter in the abomasum. They   were individually penned and offered a low protein pelleted diet at   maintenance levels. Following a five week stabilisation period 12 ewes   were infused abomasally with 100g/d whey protein concentrate in 1 litre   of water for 8 days. Twelve ewes received 1 litre of water only. Blood   samples were collected four times daily for FSH analysis, from 2 days   before until 2 days after infusion.     Protein infusion did not influence FSH levels. Mean values were 8.5   ngFSH/ml plasma for both treatments and means for individual ewes   ranged from 4.5 to 11.5 ng/ml. These results indicate that the reported   increase in FSH with increased protein intake is not due to a direct   effect on the pituitary gland.    },
	issn = {1176-5283},
	author = {Francis SM and Bickerstaffe R and O{\textquoteright}Connell D}
}
@conference {39916,
	title = {Relationships between insulin-glucose status and carcass fat in lambs},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {44},
	year = {1984},
	month = {Jan},
	pages = {201-204},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Paired 7-rib roasts from heavy ram and wether lambs fed pelleted diets were evaluated by 70 United States lamb consumers. Forty of the 70 lamb consumers preferred rib roasts from wethers. The 40 consumers preferring meat from wethers listed milder flavours along with more tender and juicier meat as reasons for their selection. The 30 consumers who preferred meat from ram lambs did so because the roasts were less greasy and the more intense flavour was preferred. Therefore, differences in intensity of flavour between meat from rams and wethers did exist but lamb consumers were divided on their preference for a stronger or milder flavour.},
	issn = {1176-5283},
	author = {Munro JM and Geenty KG and Bickerstaffe R}
}
