@conference {41153,
	title = {Role of reproductive technologies in reducing the time lag associated with the commercial application of genetic discovery in the sheep industry},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {60},
	year = {2000},
	month = {Jan},
	pages = {36-40},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	address = {Hamilton},
	abstract = {The recent and escalating emphasis on gene discovery has major implications for genetic improvement of the NZ sheep industry. However, the long lag phase in the dissemination of new genetic material through current breeding structures is a major impediment to rapid uptake of the improvements. Effective reproductive technologies are considered necessary for achieving the desired rates of dissemination but there is little evidence of their practical and economic values. To provide evidence, a series of modelling exercises were undertaken. This involved defining a particular commercial outcome (advancing the pattern of lamb kill in Otago/Southland by 1 month without changing lambing date), deciding on the relevant genetic trait to achieve this (terminal sires with a 20\% increase in mature size), modelling the rate of genetic gain using a number of breeding scenarios that included artificial insemination (AI) and multiple ovulation and embryo transfer (MOET), to determine the time required for sufficient commercial rams to be available to achieve the outcome. Selected scenarios were then chosen for more detailed modelling to ascertain the economic implications to the farm (Otago/Southland lamb finishing farm) and to the industry of adopting the technology. The advancement of the kill pattern by one month was worth $12,714 on the commercial farm. Based on a two-tiered breeding system (stud and commercial) without any reproductive technology it takes 26 years to achieve the outcome (assuming that the animal with this genetic advantage had been identified at the start). The use of AI at the stud level reduced this time by 11 years. The additional use of MOET on stud ewes gave a further reduction in time of 7 years and the application of AI using stud rams at the commercial level an additional 2 years. These results confirm the importance of reproductive technologies in reducing the lag phase in gene dissemination and their value to the industry. There is a need to further refine the efficiency and efficacy of the chosen technologies. },
	issn = {1176-5283},
	author = {Smith JF and Vetharaniam I and McCall DG and Tervit HR}
}
@conference {41140,
	title = {A Dynamical Model of Body Composition in Sheep},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {59},
	year = {1999},
	month = {Jan},
	pages = {275-278},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {A dynamical model describing the evolution of muscle, viscera and fat in response to different levels of energy intake over time in sheep is presented. The model shows responses consistent with observations of compensatory growth in sheep and cattle over a range of energy intake levels. Model parameters are derived from data measured by Ferrell et al., (1986) to investigate compensatory growth in lambs. The model is shown to generally reproduce the behaviour of the muscle, viscera and fat components of the lambs in this trial. The utility of the model for designing optimal nutritional management strategies for raising animals for slaughter is discussed, as well as the potential of the model to advance the understanding of animal nutrition by investigating different functional forms for relationships such as maintenance requirements. },
	issn = {1176-5283},
	author = {Soboleva TK and Oddy VH and Pleasants AB and Oltjen JW and Ball AJ and McCall DG}
}
@conference {41019,
	title = {The role of milk production in dryland lamb production systems},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {58},
	year = {1998},
	month = {Jan},
	pages = {170-174},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {A farmlet study was carried out over 2 years to examine the role of milk production in dryland lamb production systems. Poll Dorset and Romney ewes were used to represent high and low levels of milk production and mated to produce reciprocal cross lambs. High and low fecundity treatments were included in replicated farmlets of 2.9 ha and stocked at 15 ewes/ha. Mean lambing dates were 5th and 8th August with lambs drafted for slaughter from mid October. In Year 1, Poll Dorset ewes produced 44\% (singles) and 88\% (twins) more milk in peak lactation than their Romney counterparts. In late lactation, Poll Dorsets produced 41\% (singles) and 169\% (twins) more milk. In Year 2, the advantages were 19\% (singles) and 18\% (twins) in peak lactation and 78\% (singles) and 67\% (twins) in late lactation. Increased milk production had small effects on lamb growth rates in the low fecundity treatments (Year 1: 338 vs 328 g/d; Year 2: 317 vs 300 g/d for the respective high and low milk treatments). In the high fecundity farmlets, dam breed differences were larger (Year 1 :280 vs 244g/d ; Year 2: 307 vs 283 g/d, respectively). Number of lambs drafted by the 2nd December were also similar in low fecundity groups (Year 1: 93\% vs 95\%; Year 2: 90\% vs 93\%, respectively). Greater numbers of lambs were drafted off high fecundity Poll Dorsets than Romney dams (56\% vs 23\%) in Year 1 but not in Year 2 (85\% vs 81\%). The greater effect of milk on lamb growth in high fecundity treatments in Year 1 was attributed to poor spring feed conditions and the buffering ability of high milk producing ewes. },
	issn = {1176-5283},
	author = {Muir PD and Wallace GJ and McCall DG and Dodd CJ}
}
@conference {40695,
	title = {An evaluation of the Stockpol model},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {55},
	year = {1995},
	month = {Jan},
	pages = {145-159},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {The potential of large scale bin trapping of flies as a means of reducing  the incidence of flystrike was evaluated. Two 5 ha paddocks of similar soil  type and pasture species composition, but more than 500 m apart, were used.   From Nov. 16 to Dec. 24 flies were trapped in paddock 1 using four 2001 bin  traps baited with sheep},
	issn = {1176-5283},
	author = {Webby RW and McCall DG and Blanchard VJ}
}
@conference {40628,
	title = {The complementary contribution of the beef cow to other livestock enterprises},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {54},
	year = {1994},
	month = {Jan},
	pages = {323-328},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {This paper reviews potential benefits of beef cows to other livestock  
enterprises on a sheep and beef farm.  These benefits may include general  
benefits of cattle such as improved sheep performance via improved pasture  
quality.  They may also include benefits specific to cows such as the efficient  
use of low quality feed and feed demand patterns which match pasture  
production.  A linear programming model is used to quantify complementary  
benefits of breeding cows to the total farm economy.  This is done by  
comparing the profit from finishing only policies with those that include  
breeding cow and finishing cattle policies.  When the marginal benefit in farm  
profit is all attributed to the breeding cows their worth is between 5 and 26\%  
greater than estimated by an enterprise analysis which does not account for  
complementarity.  However, complementary benefits cease when returns from  
finishing reach $16/su greater than cows.  Field system trials are required to  
validate these conclusions. },
	issn = {1176-5283},
	author = {McCall DG}
}
@conference {40629,
	title = {Nutritional buffering: Do we make the best use of this phenomena in the breeding cow},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {54},
	year = {1994},
	month = {Jan},
	pages = {329-332},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {The nutritional buffering capacity of the beef cow, defined as the  
ability to absorb low levels of feeding without compromising productivity, is  
reviewed in regard to winter management.  It is shown that resistance to  
liveweight loss is repeatable for cows within the same herd between years  
(correlations 0.4 to 0.8, P<0.01).  However this capacity is associated with  
lower calf weaning weight (correlations 0.3 to 0.5, P<0.05).  There was no  
association between the amount of winter liveweight loss and cow liveweight,  
calf birth weight or time to first oestrus in the cow. It is shown that these  
results are consistent with evidence for the variation of maintenance  
requirements between cows. 
 
It is suggested that the buffering capacity of the beef cow could be exploited  
through animal breeding or by management of early nutrition.  There may be no  
one cow type which is optimal for all farming situations, and instead a range of  
cow types which are more or less able to buffer feed shortages may be  
preferred. 
 },
	issn = {1176-5283},
	author = {Pleasants AB and Barton RA and McCall DG}
}
@conference {40646,
	title = {The role of systems research in animal science},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {54},
	year = {1994},
	month = {Jan},
	pages = {417-422},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {This paper presents challenges to the way we conduct experimentation  
in animal science.  The theme of the paper is to show the benefits of using  
systems research methods in both our basic and applied animal science.  The  
need for more accurate prediction of biological processes to achieve future  
breakthroughs in animal production is postulated.  The use of systems research  
using dynamical systems models in our basic science to better understand and  
predict the outcome of complex biological processes is discussed.  In the  
applied science context, difficulties in translating basic (component) research  
results into recommendations for improved farm performance are emphasised.   
Equally, difficulties in designing interpretable farm system experiments are  
acknowledged.  Finally, examples are given of the benefits of using whole farm  
models to integrate component results and create a link between component  
research and improved farm system, field, experimental approaches. 
 },
	issn = {1176-5283},
	author = {McCall DG and Sheath GW and Pleasants AB}
}
@conference {40399,
	title = {Modelling herd efficiency in liveweight-selected and control Angus cattle},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {52},
	year = {1992},
	month = {Jan},
	pages = {145-148},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {The growth and sexual development of red deer calves born early  (12 male, 12 female), with an average birth date of 22 October 1990 },
	issn = {1176-5283},
	author = {McMillan WH and Morris CA and McCall DG}
}
@conference {40322,
	title = {Are yearling heifer mating and more productive beef cow breeds a worthwhile use of winter feed?},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {51},
	year = {1991},
	month = {Jan},
	pages = {265-270},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {A computer software package (REVGAIN) is being developed to  integrate closely with Animalplan. It assists breeders and their  advisers to derive relative economic values and selection criteria to  suit their breeding programme.   For farmers buying flock rams REVGAIN derives relative economic values  for their individual commercial flock, and hence the sort of breeder  from which to buy rams.   Using specific production levels, prices, and costs for the producers{\textquoteright}  or breeders{\textquoteright} situation, together with the corresponding Animalplan  phenotypic and genetic parameters, the software calculates relative  economic values that will lead to maximum economic progress in the  breeding goal. It also estimates the change in each character that will  occur from a standard amount of index selection. By comparing different  economic outcomes from changing product prices, physical inputs or  genetic responses, users derive the policy that is most appropriate to  their particular situation.  },
	issn = {1176-5283},
	author = {McMillan WH and McCall DG}
}
@conference {40358,
	title = {Factors affecting beef finishing efficiency on pasture},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {51},
	year = {1991},
	month = {Jan},
	pages = {453-458},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Nineteen cows, diagnosed 30 to 50 days after insemination as  conceiving to a double ovulation and ranging in age from 2 to 8 years,  were compared for possible signs of pregnancy toxaemia with a sample  group of 18 single-ovulating single-pregnant controls, balanced for age.  Blood samples were obtained on four occasions, between 2 and 10 weeks  before the date when the first cow was due to calve. Blood samples were  analysed for ferroxidase, albumin (A), globulin, total protein, the  ratio of albumin to globulin, magnesium, beta-hydroxybutyrate (BOH),  gamma-glutamyltransferase and serum or whole blood selenium (Se). There  were significant differences between single-pregnant and twin-pregnant  cows in the concentrations of A, BOH and whole blood Se. Least-squares  means were as follows: A, 33.7 and 32.3 g/l; BOH, 0.46 and 1.62 mmol/l;  and whole blood Se 887 and 737 nmol/l. The BOH data in particular were  useful in identifying cows possible requiring extra veterinary  supervision.  },
	issn = {1176-5283},
	author = {McCall DG and Marshall PR}
}
@conference {40277,
	title = {Impact of potential change in climate and atmospheric concentration of carbon dioxide on pasture and animal production in New Zealand},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {51},
	year = {1991},
	month = {Jan},
	pages = {25-33},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Three groups of 10 ewes each were treated with Repromap sponges  (MAP), Chronogest sponges (FGA) or Controlled Drug Release devices  (CIDR) for 11 days. At withdrawal the delay time until oestrus, LH  surge and ovulation was measured.   There was no significant difference between the two sponge treatments in  mean delay times although FGA treated ewes tended to be less variable in  their activity.   CIDR treated ewes commenced standing oestrus sooner than MAP and FGA  treated ewes (30h vs 42h and 40h respectively P<0.001). Similarly the  onset of the LH surge (31h vs 46h and 46h P<0.001) and ovulation (59h vs  69h and 71h P<0.001) occurred sooner in the CIDR ewes compared to MAP  and FGA sponges.  },
	issn = {1176-5283},
	author = {Martin RJ and Korte CJ and McCall DG and Baird DB and Newton PCD and Barlow ND}
}
@conference {40161,
	title = {The effect of integrated grazing of goats, sheep and cattle on animal productivity and health on high-producing hill country pastures},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {49},
	year = {1989},
	month = {Jan},
	pages = {165-170},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {A selection experiment at Waikite (Rotorua) began in 1971 with closed Angus herds selected for adjusted 13-month weight (AS1), adjusted 18-month weight (AS2) or with random replacement (ACO). A closed Hereford herd, selected for adjusted 13-month eight (HS1), was also established. At both 13 and 18 months of age, annual responses in live weight in the AS1, HS1 and AS2 herds averaged 0.96, 0.62 and 0.48\% of the ACO herd means (calvings 1972-85). Five correlated responses were estimated. 1. Cow weight: From all ages of cows recorded over 4 seasons (on average 11 years of selection completed), AS1 and AS2 cows were 7.5 and 8.2\% heavier respectively than ACO cows; HS1 cows were 2.5\% heavier than AS1 cows, the same margin as in 1971. 2. Maternal weaning weight: (AS1 and AS2 herds only, relative to ACO): responses was estimated in a tester herd from calvings in 1982-86. The maternal grandsires were selected AS1 and AS2 bulls born after almost 2 generations (6 years) of selection. The AS1 herd was superior by 8.6 kg (5.7\%) and the AS2 herd by 2.2 kg (1.5\%). 3. Scrotal circumference: From the 1982-85 crops, the AS1 and AS2 bulls had respectively 0.9 (P<0.01) and 0.3 cm larger circumferences at 13 months of age and 0.7 (P<0.01) and 0.4 cm below corresponding AS1 values. 4. Height at withers: AS1 and AS2 bulls from the 1981 calf crop were respectively 3.5 and 2.5 cm taller (P<0.05) than the ACO bulls; the HS1 bulls were 2.3 cm taller (P<0.05) than the AS1 bulls. 5. Food intake: Average intake of silage by Angus bulls from the 1980 and 1981 crops were 10.4\% and 11.7\% greater (P<0.01) for AS1 and AS2 than ACO cattle respectively. Expressed relative to body weight, there was no significant difference due to herd. The pooled regression of daily intake of dry matter on 18-month weight was 0.0091 kg/kg (P<0.05), with a correlation of 0.32. The correlations of pre-fasting plasma tryptophan and the fall in plasma tryptophan concentration with average previous intake were 0.50 and 0.41, for bulls fasted over a 48 h period.},
	issn = {1176-5283},
	author = {Bown MD and McCall DG and Scott ML and Watson TG and Dow BW}
}
@conference {40159,
	title = {Nutrition effects on live weight and reproduction of Cashmere doe hoggets},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {49},
	year = {1989},
	month = {Jan},
	pages = {157-162},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Often effective breeding programmes are dependent on the assumption that heritabilities and genetic correlations between traits are the same in both sexes and that the genetic correlation for the same trait measured on both sexes is unity. A total of 12 302 records from 149 sire groups were analysed using mixed model techniques to test these assumptions. The results provide an indication that genetic and phenotypic parameters differ for male and female sheep. Cognizance of this fact should be taken when considering alternative selection strategies.},
	issn = {1176-5283},
	author = {McCall DG and Clayton JB and Dow BW}
}
@conference {40169,
	title = {Relative wool production of wethers and ewes of different rearing status},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {49},
	year = {1989},
	month = {Jan},
	pages = {209-214},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Low growth rates in autumn have been described in cattle and sheep in New Zealand and overseas. Comparison of responses in liveweight gain to herbage allowance has shown that animals grazing in autumn grow much more slowly at all allowances than those grazing in spring. When autumn- and spring-born lambs were grazed together, responses in liveweight gain to varying herbage allowance did not depend on their age and/or live weight. There were large differences between the responses of animals grazing in autumn and those grazing in spring. In autumn, animals grazing pasture previously sprayed with high rates of fungicide at high allowances gained weight 28\% faster than those grazing unsprayed pasture - 107.2 v 83.7 g/d. In spring, the use of fungicide on pasture had no significant effect on liveweight gains of lambs.},
	issn = {1176-5283},
	author = {Sumner RMW and McCall DG}
}
@conference {40124,
	title = {Calf weaning and summer grazing strategies for efficient beef cow use on hill country},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {48},
	year = {1988},
	month = {Jan},
	pages = {237-242},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {No abstract supplied},
	issn = {1176-5283},
	author = {McCall DG and Scott ML and Dow BW}
}
@conference {40012,
	title = {Calving date effects on beef cow productivity},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {46},
	year = {1986},
	month = {Jan},
	pages = {149-152},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {An agonist of gonadotrophin releasing hormone (GnRH) improves dairy cow pregnancy rates when injected at an appropriate stage after insemination. These studies were extended to ewes and hoggets in a series of trials to determine the effects of a single injection of GnRH made at varied intervals after mating. All sheep were mated at a synchronised oestrus (day of oestrus = day 0) with treated ewes being injected on a set date with 2 or 4 },
	issn = {1176-5283},
	author = {Smeaton DC and McCall DG and Clayton JB and Dow BW}
}
@conference {40006,
	title = {The influence of sheep to cattle ratios in live-weight gain on pastures grazed to different levels in late spring-summer},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {46},
	year = {1986},
	month = {Jan},
	pages = {121-124},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {A survey of 30 Wairarapa hill country farmers during 1983 investigated how management practices influenced sheep performance. Lamb growth rates between birth and weaning which ranged from 153 to 300 g/d, were most affected by lambing date and the use of N fertiliser. Pasture cover/SU at lambing was more often a limitation to high lamb growth rates on early lambing farms, but even on later lambing properties insufficient feed at lambing was common. Pasture cover/SU at lambing was most affected by ewe winter rotation length, the use of N fertiliser, stocking rate and stock policies which enabled winter stocking rates to be progressively reduced. Weighing of sheep was associated with the attainment of higher autumn live weights. A high proportion of farmers weighted (63\%), but their knowledge of acceptable live weights was poor.},
	issn = {1176-5283},
	author = {McCall DG and Smeaton DC and Gibbison ML and McKay FJ and Hockey H-UP}
}
@conference {40008,
	title = {Lambing date, ewe live weight and pasture mass effects on ewe and lamb performance during lactation},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {46},
	year = {1986},
	month = {Jan},
	pages = {129-132},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {A series of 4 herbage allowance trials was conducted over 2 years with beef cattle on a well-drained site in Northland. Two trials were conducted in autumn/winter (April-July) and 2 in spring (October and November). Analysis of the data, for each seasonal period combined over the 2 years, showed large differences in the relationships between daily live- weight gain and herbage allowance between the 2 seasons. At the same allowance, beef cattle grew faster in spring than in autumn/winter. Relationships between allowance and daily live-weight gain were: Autumn/winter: LWG = 0.48-1.37* 0.65 allowance Spring:    LWG = 1.09-2.82* 0.45 allowance These differences were not associated with differences in in vitro digestibility (70 to 78\% in all trials) or N concentrations. Allowances required for maintenance were lower in spring than in autumn/winter and potential growth rates in spring approximately double those in autumn.},
	issn = {1176-5283},
	author = {McCall DG and Smeaton DC and Wadams TK and Gibbison ML}
}
@conference {39897,
	title = {Relative priorities for feed between ewes and ewe hoggets in winter and spring: a modelling analysis},
	booktitle = {Proceedings of the New Zealand Society of Animal Production},
	volume = {44},
	year = {1984},
	month = {Jan},
	pages = {121-124},
	publisher = {New Zealand Society of Animal Production},
	organization = {New Zealand Society of Animal Production},
	abstract = {Grazing animals obtain most of the mineral nutrients they require from pasture plants. Whilst a knowledge of plant composition alone is of limited value, it is one of a series of clues which can be used to help diagnose or predict animal mineral status. Factors which influence the concentration and availability of minerals in plants are summarised in an attempt to aid the interpretation of plant analyses.},
	issn = {1176-5283},
	author = {McCall DG}
}
