@article {3672, title = {Farm-management tools: reasons for the decision not to use specific tools}, journal = {New Zealand Journal of Animal Science and Production}, volume = {79}, year = {2019}, month = {07/2019}, pages = {125-130}, address = {Palmerston North}, abstract = {There are a large number of management tools available to farmers, however, some are utilised by only a small percentage. The reasons behind the choice not to use a particular tool were investigated using a postal questionnaire that was distributed to all New Zealand sheep farmers in 2014. Farmers were asked first to indicate from a list of 40 farm-management tools those they had used in the previous three years. For tools they had not used, they were asked to select one from a list of eight reasons. A total of 1659 usable questionnaires were received. The most commonly cited reason for not using any given tool was {\textquotedblleft}not relevant to my situation{\textquotedblright} (50.3\%) followed by {\textquotedblleft}benefits not apparent{\textquotedblright} (15.3\%) and {\textquotedblleft}it{\textquoteright}s an unwanted complication{\textquotedblright} (15.0\%). Demographic factors (age, education, gender, farm type and flock size) influenced the reasons for non-use of 20 of the 22 tools. Reasons for non-use of fecundity-boosting vaccine or quarantine treatment for footrot were not influenced (P>0.05) by any demographic factors. The results suggest that although many farmers do not see the relevance of particular tools to their enterprise, demographic factors can influence their reasons for not using a tool. }, issn = {1176-5283}, author = {Corner-Thomas RA and Kenyon PR and Morris ST and Ridler AL and Hickson RE and Greer AW and Logan CM and Blair HT} } @article {3672, title = {Faecal avoidance in Romney sheep lines selected for resistance or resilience to gastro-intestinal nematodes}, journal = {New Zealand Journal of Animal Science and Production}, volume = {78}, year = {2018}, month = {07/2018}, pages = {100-104}, address = {Lincoln}, abstract = {Faecal avoidance was assessed in Romney lambs from lines selected for resistance or resilience to gastro-intestinal nematode parasites. Ten lambs from each selection line that were maintained in separate farmlets and naturally exposed to parasites were assessed on distance grazed from either a mud-clay or faecal ball at 130, 150, 180 and 210 days-of-age. Resistant line animals maintained lower faecal-egg counts compared with resilient lambs, viz. 25.6 c.f. 771.0 eggs per gram of faeces (P<0.001) and greater Trichostrongylus colubriformis-specific immunoglobulin G absorbance (P=0.005) indicating differences between selection lines in parasite loading and immunlogical status. Grazing distance from the object was greatest for faecal ball, viz. 11.53 {\textpm} 1.14 cm compared with mud-clay ball, viz. 4.19 {\textpm} 1.00 cm (P<0.001) and decreased with time (P<0.001). Grazing distance tended to be greater for resilient, viz. 8.63 {\textpm} 1.14 cm than resistant, viz. 7.09 {\textpm} 0.99 cm (P=0.09) but there was no interaction between selection line and ball type (P=0.709) indicating similar levels of faecal-specific aversion between the selection lines. These results suggest that the lesser infection levels in resistant-line animals when grazing is unlikely to be due to reduced exposure to infective larvae as a consequence of greater faecal avoidance.}, issn = {1176-5283}, author = {Hamie JC and Logan CM and McAnulty RW and Greer AW} } @article {3672, title = {Investigation into udder characteristics, mastitis and milk production in crossbred sheep}, journal = {New Zealand Journal of Animal Science and Production}, volume = {78}, year = {2018}, month = {07/2018}, pages = {82-87}, address = {Lincoln}, abstract = {Associations between udder characteristics, milk yield, milk somatic cell counts (SCC) and prevalence of mastitis were evaluated in 121 twin-suckled crossbred non-dairy ewes at four, eight and twelve weeks after parturition. Overall, milk production decreased with time, being 1.09 {\textpm} 0.04 litres per four hours at week four of lactation, 0.68 {\textpm} 0.02 litres at week eight and 0.48 {\textpm} 0.01 litres at week twelve with corresponding mean SCC of 0.32 x 106 cells mL-1, 0.39 x 106 cells mL-1 and 0.28 x 106 cells mL-1, respectively. Incidence of mastitis was 12.7\%, 9.8\% and 8.9\% for weeks 4, 8 and 12, respectively. Of the 20 individuals that displayed SCC indicative of mastitis, only 5 had elevated SCC at more than one sampling time. No consistent association was observed between SCC and visual scores for udder depth, udder distention, degree of separation or teat placement (P>0.05 for all). Milk volume and weight of lamb was greater for ewes with an udder depth of 3 compared with 4 with no other associations evident (P>0.05). Overall, the incidence of subclinical mastitis was low but present in this flock with the udder characteristics assessed here providing poor indicators of either mastitis or milk production.}, issn = {1176-5283}, author = {Yusuf OM and Logan CM and Ridler AL and Greer AW} } @article {3672, title = {Supplementation of ewes on pasture to provide an epidemiological benefit for gastrointestinal parasitism}, journal = {New Zealand Journal of Animal Science and Production}, volume = {78}, year = {2018}, month = {07/2018}, pages = {45-50}, address = {Lincoln}, abstract = {The potential epidemiological benefit of reducing the peri-parturient relaxation in immunity to gastro-intestinal nematode parasites through supplementing twin-bearing ewes during the first four weeks of lactation was evaluated in a replicated farmlet study. In two sequential years, ewes either grazed pasture alone or grazed pasture while supplemented with 0.5 kgDM/d of a high-protein pellet. Supplementation did not affect ewe live weight or body condition score or weight of lamb weaned per ewe (P>0.05). Ewe faecal egg counts (FEC) showed a time x supplementation interaction (P<0.05), being reduced by 50\% from week six of lactation in both years, although this only resulted in transient and inconsistent reductions in pasture larval contamination. After weaning, there was no consistent parasitological benefit to lambs grazing areas where ewes had been supplemented that were reflected in either pasture larvae concentrations, lamb FEC, the requirement for anthelmintic treatment or lamb growth rate (P>0.05 for all). Despite supplementation of ewes during the first four weeks of lactation successfully reducing ewe faecal egg count by 50\%, this was not sufficient to provide a measureable and consistent epidemiological benefit to the lambs.}, issn = {1176-5283}, author = {Tambunan RD and Logan CM and Bywater AC and Greer AW} } @conference {3672, title = {Potential anthelmintic properties of urea}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {77}, year = {2017}, month = {06/2017}, pages = {110-113}, address = {Rotorua}, abstract = {Current gastrointestinal parasite treatment options rely heavily on chemical anthelmintic intervention which targets the nematode residing in the host. However, targeting these organisms during parts of their lifecycle outside the host may also provide a tool for aiding control. In particular, nitrogenous fertilisers produce several potentially toxic compounds, the strategic use of which may affect nematode development. This series of experiments investigated the potential of liquid urea to affect gastrointestinal nematode development. Hatching of Trichostrongylus colubriformis eggs when immersed in liquid urea reduced with increasing urea concentration from 90\% at 0\% urea to less than 6\% in 20\% urea solution. This effect was independent of pH and appeared to be nematocidal rather than nematostatic as unhatched eggs failed to hatch following washing and immersion in water. Further, topical application of liquid urea to faeces at a rate equivalent to 200 litres per ha (40 units N) on fresh faeces resulted in a 97\% reduction in the number of larvae recovered following culturing compared with equivalent rates of water (P<0.01). Although further studies and refinement are required, these studies indicated targeted application of liquid urea may be a useful tool to assist with parasite control.}, issn = {1176-5283}, author = {Cairns J and McAnulty RW and Greer AW} } @conference {3672, title = {BRIEF COMMUNICATION: The use of farm-management tools by New Zealand sheep farmers: changes with time}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {76}, year = {2016}, month = {07/2016}, pages = {78-80}, address = {Adelaide}, abstract = {The utilisation of farm-management tools by New Zealand sheep farmers can support on-farm decision making, thus facilitating improvements in productivity and profitability of the farming enterprise. There are numerous management tools available to farmers, for example, a recent report identified 127 tools that were available to New Zealand farmers (Allen \& Wolfert 2011). Although a large number of tools are accessible to farmers, a survey of sheep farmers conducted in 2012 by Corner-Thomas et al. (2015) identified many that were utilised by only a small percentage of farmers. This indicates that there is the potential for increased uptake of management tools which, if relevant, may lead to benefits in on-farm productivity. The aim of the current study was to determine for sheep farmers in New Zealand, if use of farm-management tools had changed over a two-year period.}, issn = {1176-5283}, author = {Corner-Thomas RA and Kenyon PR and Morris ST and Ridler AL and Hickson RE and Greer AW and Logan CM and Blair HT} } @conference {3672, title = {The influence of previous reproduction on subsequent fertility in multiparous ewes}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {76}, year = {2016}, month = {07/2016}, pages = {155-158}, address = {Adelaide}, abstract = {Adult ewes often lose live weight while lactating, but should regain it prior to the following mating if pasture availability or sheep numbers are managed judiciously. Data from a self-replacing flock of Wiltshire ewes four to nine years of age (n=267) was available for 622 lambing events across a 13-year period. Wiltshires grow little wool and live weight was not complicated by fleece weight. The average number of lambs born was 1.76 per ewe per year during the course of the study. Ewes not rearing a lamb (13.2\%), or rearing singles (42.4\%), twins (42.4\%), or triplets (1.9\%), were present at weaning. All ewes were grazed together and when their lambs were weaned, those that did not raise a lamb (67.4 {\textpm} 9.7 kg) were heavier than ewes that raised singles (63.0 {\textpm} 9.3 kg), twins (59.9 {\textpm} 8.5 kg) or triplets (59.7 {\textpm} 7.7 kg) (P<0.001). Despite this, the previous number of lambs weaned did not influence the number of lambs born in the subsequent year (P = 0.43), but was positively associated with ewe liveweight gain between weaning and mating (P<0.01). Number of lambs born was positively influenced by ewe live weight at mating up to 65 kg. Reproductive performance was not influenced by the previous year, providing ewes were able to increase live weight between weaning and mating.}, issn = {1176-5283}, author = {Scobie DR and O{\textquoteright}Connell D and Noble A and Greer AW} } @conference {3672, title = {BRIEF COMMUNICATION: Optimizing a fasting protocol to assess live weight of sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {75}, year = {2015}, month = {07/2015}, pages = {223-224}, address = {Dunedin}, abstract = { }, issn = {1176-5283}, author = {Wilson RF and Hardwick-Smith JA and Logan CM and Corner-Thomas RA and Bywater AC and Greer AW} } @conference {3678, title = {BRIEF COMMUNICATION: Ewe ultra-sound pregnancy diagnosis and its use by New Zealand farmers}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {74}, year = {2014}, month = {06/2014}, pages = {65-67}, address = {Napier}, abstract = {Ultra-sound pregnancy diagnosis can be a valuable management tool for sheep farmers. The benefits include early identification of non-pregnant (dry) ewes which can be culled, freeing up valuable feed for pregnant ewes (Blair 1986) and the identification of single, twin and triplet fetuses, allowing ewes to be fed based on their specific nutritional requirements during pregnancy (Garrick 1998). In addition, selection of lambing paddocks can be made based on the number of fetuses identified (Garrick 1998).}, issn = {1176-5283}, author = {Corner-Thomas RA and Kenyon PR and Morris ST and Ridler AL and Hickson RE and Greer AW and Logan CM and Blair HT} } @conference {3678, title = {BRIEF COMMUNICATION: Performance of lambs exposed to a desensitising regime prior to infection with Trichostrongylus colubriformis}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {74}, year = {2014}, month = {06/2014}, pages = {73-75}, address = {Napier}, abstract = {Enhancing the immune response of lambs against the gastrointestinal nematode Trichostrongylus colubriformis through vaccination has been previously investigated (Windon et al. 1984; Douch 1989; McClure 2009). However, the majority of production loss from this parasite species in sheep has been attributed to components of the immune response (Greer et al. 2005). As such, manipulation of the host immune response through desensitisation may provide a novel method of reducing production loss associated with infection. The objective of this investigation was to evaluate the ability of a desensitising regime with parasite antigens to reduce the production cost associated with Trichostrongylus colubriformis infection in lambs...}, issn = {1176-5283}, author = {Greer AW and Huntley JF and Hogan A and Logan CM and McAnulty RW and McNeilly TN} } @conference {3678, title = {Predicting fleece weight from the difference in live weight pre- and post-shearing}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {74}, year = {2014}, month = {06/2014}, pages = {68-72}, address = {Napier}, abstract = {Radio frequency identification (RFID) and automated weighing platforms facilitate the practicality and ease with which individual live weight (LW) can be recorded. This raises the possibility for the difference in recorded LW of sheep between pre- and post-shearing to provide an estimate of fleece weight (eFW) which, in turn, could allow selection pressure to be applied for improved wool production. The eFW of yearling ewes (n=98), yearling rams (n=274) and mixed-age ewes (n=305) were compared with their recorded fleece weight (FW). Positive linear correlations (P<0.001 for all stock classes) were observed between eFW and FW and also the eFW rank and FW rank. Although some variability between stock classes existed, for all data combined, FW rank was able to account for 42\% of the variation in eFW rank. Further, selecting individuals on eFW was able to retain an average of 64\% of the selection differential obtained using recorded FW. Overall, these results suggest eFW calculated from the difference in LW between pre- and post-shearing, in combination with RFID and automated weighing platforms, may provide a useful and practical tool to assist with selection for improved wool production in a commercial setting.}, issn = {1176-5283}, author = {Galway JM and Logan CM and Bywater AC and Greer AW} } @conference {89241, title = {Can weighing multiple times increase the accuracy of live weight recording?}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {73}, year = {2013}, month = {Jan}, pages = {146-148}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {

The recording of live weight in livestock enterprises is fundamental for breeding and production, the ease of which has been greatly improved with the advent of automated weighing and recording platforms. However, the extent to which significant advances within a livestock enterprise can be made with the utilization of live weight data depends on the validity of the indicated weights which can be influenced by measurement error from a number of sources (Hughes 1976). Thus, the use of scales only provides an estimate of an animal{\textquoteright}s true live weight. Despite the importance of live weight, there is a distinct paucity of published data surrounding the variation in live weight estimates and weighing protocols that may be used to reduce this variation.

}, issn = {1176-5283}, author = {Galwey JM and Logan CM and Greer AW} } @conference {89248, title = {Evaluation of lambs subjected to a targeted selective treatment anthelmintic regime}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {73}, year = {2013}, month = {Jan}, pages = {175-179}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Hamilton}, abstract = {

Targeted selective anthelmintic treatments (TSTs) can identify individuals less reliant on anthelmintic, information from which could be utilised to select lambs based on anthelmintic requirement. However, it is important to first determine if selection based on anthelmintic requirement compromises genetic potential for productive traits. Sheep Improvement Limited (SIL) estimated breeding values (eBVs) for production traits and associated indexes for 214 female lambs and 158 male Coopworth lambs were compared with their requirement for anthelmintic following exposure to a liveweight gain-based TST regime. Mean liveweight gain for both sexes was reduced with increasing anthelmintic requirement (P \<0.001). Favourable increases in eBVs with decreasing anthelmintic requirement wereobserved for fecundity in both sexes (P = 0.003) and for survival in females only (P = 0.03). No effect was observed for eBVs for maternal survival, weaning weight, maternal weaning weight, live weight at eight months of age, and live weight and fleece weight at 12-months of age (P \>0.05 for all). Dual purpose index values for resilience increased with decreasing anthelmintic requirement (P \<0.001) while meat yield index and overall productivity were not affected (P \>0.05 for both). It is concluded that selection of lambs for low anthelmintic requirement can be made with no apparent compromise in the genetic potential for production traits.

}, issn = {1176-5283}, author = {Greer AW and Pettigrew CA and Logan CM} } @conference {79020, title = {Are faecal egg counts approaching their "sell-by" date?}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {72}, year = {2012}, month = {Jan}, pages = {199-204}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {Historically, the primary determinant for the state of parasitism has been the concentration of nematode eggs in the faeces (FEC). This descriptor has a number of limitations that have implications for the development of drug resistance and hamper the identification of resilient livestock. A major fallacy is that FEC can reliably assess the worm burden, the need for anthelmintic and the efficacy of that treatment. FEC is a ratio, eggs per gram of faeces, not a quantity. Not only is the denominator ignored but interpretation of the numerator requires knowledge of nematode species present and female fecundity which can be affected by infra-population dynamics. By definition, a parasite exists at the expense of its host. As such, the consistent ability of resilient animals to maintain performance, despite a high FEC, strongly suggests that FEC does not provide a reliable indicator of the cost of parasitism. This manuscript reviews the factors that affect FEC and argues for a step change in our approach to the control of nematode parasitism in pastoral systems to one focused on individual treatments based on animal performance utilising radio-frequency electronic identification and automated weighing and drafting systems.}, issn = {1176-5283}, author = {Greer AW and Sykes AR} } @conference {78974, title = {Presidential Address 2011 - The changing face of agriculture}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {72}, year = {2012}, month = {Jan}, pages = {1-2}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {

Agriculture is continually changing. For a large part change is essential, from the seasonal changes in animals and plants through to the inevitable changes in land use and labour requirements as technological improvements and market forces take effect. Indeed, things have changed somewhat since I was a young boy growing up on a farm in rural Southland. In my youth I would have had to travel for nearly an hour to the nearest dairy farm. But by the time I was at university, about ten years ago, the district had started to ... continued

}, issn = {1176-5283}, author = {Greer AW} } @conference {75927, title = {BRIEF COMMUNICATION: Liveweight gain of grazing dairy calves in their first season subjected to a targeted selective anthelmintic treatment (TST) regime}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {71}, year = {2011}, month = {Jan}, pages = {301-303}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Invercargill}, abstract = {For some time now it has been recognised that suppressive anthelmintic regimes select strongly for resistance (Jackson \& Miller, 2006). However, despite widespread anthelmintic resistance on beef properties in New Zealand (Waghorn et al., 2006), little attention has been paid to the sustainability of anthelmintic practices in... Continued}, issn = {1176-5283}, author = {McAnulty RW and Gibbs SJ and Greer AW} } @conference {69507, title = {Suitability of the Happy Factor decision support model as part of targeted selective anthelmintic treatment in Coopworth sheep}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {70}, year = {2010}, month = {Jun}, pages = {213-216}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Palmerston North}, abstract = {The suitability of the Happy Factor decision support model as the determinant of a targeted selective treatment regime incorporated into an automated weighing and drafting facility was evaluated in a Canterbury environment. One hundred and twenty, six-month-old Coopworth lambs naturally infected with gastrointestinal parasites were weighed and faecal sampled every two weeks for eight weeks. Individual performance targets during each two week period were calculated using the Happy Factor decision support model. Lambs that did not reach their performance target were automatically drafted out and subsequently treated with anthelmintic. Those deemed to benefit from treatment had significantly greater faecal egg count (FEC) than their untreated counterparts at Week 4 only, were lighter on Weeks 2 and 8, but had lower liveweight gains on all four occasions. Overall, the system provided a rapid and reliable method of identifying and separating poorer performing individuals, which were not necessarily those with a high FEC or those that were lighter. Furthermore, the optimum treatment threshold was determined to be 0.74, which is greater than previously published values of 0.66 for Scottish Blackface sheep. This suggests that validation of an optimum Happy Factor treatment threshold for each environment and/or animal genotype may be required.}, issn = {1176-5283}, author = {Greer AW and McAnulty RW and Logan CM and Hoskin SO} } @conference {41640, title = {Further studies on the role of suckling in the parasite status of very young lambs infected with Teladorsagia circumcincta}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {66}, year = {2006}, month = {Jan}, pages = {187-192}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Napier}, abstract = {This study investigated the role of suckling on the resistance and resilience of lambs during the period - six to 20 weeks after lambing. Eighty, 42-day old twin-born lambs were allocated to four treatment groups in which lambs continued to suckle (S-) or were weaned (W-), while concurrently infected with either 0 (-N) or 1000 (-I) L3 Teladorsagia circumcincta larvae d-1. Faecal egg counts peaked at 680, 1600, 260, and 225 eggs g-1 of fresh faeces in SI, WI, SN and WN lambs, respectively. Live weight gain was reduced from day 98 of age as a consequence of weaning (p<0.001) and infection (p=0.008). Serial slaughter on days 84, 112, and 140 indicated that suckling reduced the number of adult worms in SI compared with WI lambs though significantly so only on day 112 (p<0.05). In vitro larval establishment decreased (p<0.001) with slaughter age but was not influenced by suckling or infection (p>0.05). These results suggest that suckling may inhibit nematode development at a later stage than the immediate entry of incoming L3 larvae. In addition, suckling does not appear to confer greater resilience during T. circumcincta infection in young lambs. }, issn = {1176-5283}, author = {Iposu SO and Greer AW and McAnulty RW and Stankiewicz M and Sykes AR} } @conference {41871, title = {Plasma protein loss in lambs during a mixed infection of Trichostrongylus colubriformis and Teladorsagia circumcincta - a consequence of the immune response?}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {66}, year = {2006}, month = {Jan}, pages = {83-87}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Napier}, abstract = {Modelling is being used to compare and contrast farm management strategies. A Whole Farm Model (WFM) has been developed that links models for cow metabolism ({\textquoteleft}Molly{\textquoteright}) and pasture growth driven by climate, with management policies. It has been evaluated against trial data and the challenge is to now use it for prediction. This requires that cows be initializedso that their production is determined by their environment and genotype. Livestock Improvement Corporation has developed a system of quantifying genotype through production values (or PV{\textquoteright}s). The aim of this study was to assess the ability of the WFM to predict Strain Trial cow production using PVmilk. The relationship between PVmilk and milk yield and composition was determined by allowing a parameter within {\textquoteleft}Molly{\textquoteright} to adjust so that predicted matched actual production for 3 Strain herds and one Jersey herd. WFM was then initialized using observed PVmilk to set genotype of each cow in 8 other Strain herds and farmlets were simulated for 2003/04 season. Predictions were considered useful if the prediction errors for milk yield and milksolids (629 L and 61 kg MS respectively) were lower than the observed standarddeviations (825 L and 66 kg MS respectively) i.e. meaning model predictions of observed values were more accurate than simply using the mean as an estimate of observed values. The consistent under-prediction of milk yield and milksolids require further adjustments to the initialization of the model. PVmilk has the potential to set genotype in {\textquoteleft}Molly{\textquoteright}, within the WFM.}, issn = {1176-5283}, author = {Vaughan AL and Greer AW and McAnulty RW and Sykes AR} } @conference {41528, title = {Corticosteroid treatment prevents the reduction in food intake and growth in lambs infected with the abomasal parasite Teladorsagia circumcincta}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {65}, year = {2005}, month = {Jan}, pages = {9-12}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {Recent studies with Trichostrongylus colubriformis have provided some direct evidence to support the view that the major contributor to reduced production in gastrointestinal nematode infections is the host immune response, rather than damage from the parasite per se. However, it is unknown if this is also true for abomasal infections. Parasite na{\"\i}ve lambs were either trickle infected with Teladorsagia circumcincta L3 larvae; similarly infected and concurrently immuno-suppressed with the corticosteroid methylprednisolone acetate; immuno-suppressed only; or remained as controls. Immuno-suppression abrogated the reduction in intake and subsequent production losses and reduction in feed conversion efficiency associated with infection suggesting the damage caused by this abomasal parasite per se may have little detrimental effect on lamb productivity. These findings add weight to the view that components of the developing immune response are generally the cause of reduced productivity in infected lambs. They may have ramifications for the genetic selection of animals that are predisposed to mount a strong immune response. KEYWORDS: immuno-suppression; nematodes; intake; feed conversion efficiency; sheep. }, issn = {1176-5283}, author = {Greer AW and McAnulty RW and Stankiewicz M and Sykes AR} } @conference {41564, title = {The role of suckling on the parasite status of very young lambs infected with Teladorsagia circumcincta}, booktitle = {Proceedings of the New Zealand Society of Animal Production}, volume = {65}, year = {2005}, month = {Jan}, pages = {182-185}, publisher = {New Zealand Society of Animal Production}, organization = {New Zealand Society of Animal Production}, address = {Christchurch}, abstract = {This study investigated the importance of suckling for the resistance and/or resilience of very young lambs to Teladorsagia circumcincta nematode infection. Thirty, 6-week old twin-born lambs were allocated to four treatment groups in a 2 x 2 factorial design in which groups continued to suckle (S-) or were weaned (W-), and concurrently not infected (-N) or infected (-I) with 1000 L3 larvae of T. circumcincta per day while grazing {\textquoteleft}clean{\textquoteright} pasture for six weeks, and then slaughtered. There was a significant infection by time interaction on faecal egg counts (FEC; P < 0.001). Suckling/weaning had no effect on FEC. Worm burdens were similar in suckled-infected (SI) and weaned-infected (WI) lambs (8029 + 1502 vs 12228 + 1704 worms, SEM; P > 0.05), respectively. Eggs per utero were significantly greater (29 + 6 vs 15 + 1 eggs, SEM; P < 0.05) in SI than WI lambs, while length of female worms was similar in both groups (10.2 + 0.2 vs 9.7+0.3mm, SEM; P > 0.05), respectively. The two suckled groups progressively gained more weight (P<0.001), while uninfected lambs of both groups were heavier (P < 0.05) from day 28 onwards. Weight gain averaged 122, 282, 98, and 240g day-1 for the WN, SN, WI, and SI lambs, respectively. The study has not shown any advantage of suckling while grazing for lambs{\textquoteright} resistance or resilience to larval intake within the 12-week post lambing period. KEYWORDS: Teladorsagia circumcincta; suckled lambs; resistance; resilience. }, issn = {1176-5283}, author = {Iposu SO and Greer AW and McAnulty RW and Stankiewicz M and Sykes AR} }