Browsing by Author "Kenyon, PR"

Now showing 1 - 5 of 5
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    Does Viagra protect fetal lambs against maternal pregnancy toxaemia?
    (New Zealand Society of Animal Production, 2016) Peterson, SW; Pain, SJ; McCoard, SA; Oliver, M; Baker, PB; Kenyon, PR; Blair, HT
    Poor fetal growth is commonly caused by placental insufficiency. In sheep, multiple fetuses have relatively small placentae with fewer cotyledons than singletons, limiting blood flow to the placenta, especially in late gestation when fetal growth rate is highest. Factors that reduce fetal growth, such as maternal genotype, nutrition, age, parity, fetal number, or environmental temperature, typically reduce placental size and are associated with lower rates of fetal oxygen and nutrient uptakes and placental blood flow (Reynolds & Redmer 2001). Further, circumstances that influence placental vascular development have a dramatic impact on fetal growth and development, and affect neonatal survival and growth (Borowicz et al. 2007; Satterfield et al, 2010). Sildenafil citrate (SC, trade names Viagra or Avigra) increases vasodilatation of uteroplacental vessels (Wareing et al. 2005) and may represent a novel therapy to improve fetal lamb growth. Sildenafil citrate has successfully increased birth weight in rodent models and singleton bearing ewes (Satterfield et al. 2010; Miller at al. 2009). There is no published information regarding the use of SC in multiple-bearing ewes. The objective of this trial was to determine if SC administration to triplet-bearing ewes in late gestation could increase lamb birth weight. In addition, the influence of SC on the incidence of pregnancy toxaemia is also reported here.
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    Growth of early weaned lambs on a plantain-clover mix compared with lambs suckling their dam on a plantain-clover mix or a grass based sward
    (NZSAP, 7/07/2016) Cranston, LM; Corner-Thomas, RA; Kenyon, PR; Morris, ST
    Plantain-clover mixes have high metabolisable energy content and have been shown to support greater liveweight gains in lambs both pre- and post-weaning when compared with grass. The aim of this experiment was to determine if a plantain-clover mix could be used as a means to wean lambs earlier. Twin-bearing ewes (n=67) with both lambs at a minimum live weight of 16 kg each were allocated to one of three treatments; 1) ewe and lambs together on grass, 2) ewes and lambs together on plantain- clover mix, 3) lambs weaned at approximately 8 weeks of age onto a plantain-clover mix and ewes on grass. Lambs that were weaned early were lighter (P<0.05) at approximately 14 weeks of age than those which remained with their dam on either a plantain-clover mix or grass (32.3±0.43 vs 34.7±0.44 vs 33.7±0.45 kg, respectively). However, ewes which had their lambs weaned early were heavier (P<0.05; 79.7±1.73 vs 75.5±1.68 vs 75.9±1.64 kg, respectively) and in better body condition score (P<0.05; 3.1±0.05 vs 2.9±0.05 vs 2.9±0.05, respectively) than those which remained with their lambs on either a plantain-clover mix or grass. This suggests early weaning improved ewe condition but did not improve lamb performance
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    Improved extension practices for sheep and beef farmers
    (New Zealand Grassland Association Occasional Publication, 14/04/2016) Gray, DI; Sewell, AM; Hartnett, M; Wood, BA; Kemp, PD; Blair, HT; Kenyon, PR; Morris, ST
    Innovation is critical for maintaining New Zealand’s competitive advantage in agriculture and central to this is farmer learning and practice change. Despite the importance of farmer learning, limited research has been undertaken in New Zealand. In this study, an extension programme was developed based upon educational theory and research and then evaluated over a 3 years to identify the factors that were important for farmer learning and practice change. This paper provides a brief overview of findings of a 3 year interdisciplinary study conducted at Massey University with 23 farmers that investigated the critical factors that support farmers’ learning. The five critical success factors and the seven educational principles identified from this study provide guidelines for how science should interact with farmers to foster effective innovation. These findings are also applicable to other extension approaches such discussion groups, monitor farms and sustainable farming fund initiatives where farmers work with scientists and/or rural professionals.
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    Reproductive performance of singleton and twin female offspring born to ewe-lamb dams and mature adult dams
    (New Zealand Society of Animal Production, 7/07/2016) Loureiro, MFP; Kenyon, PR; Pain, SJ; Blair, HT
    This study was undertaken to compare the reproductive and live weight performance of female singleton and twin ewes born to either mature or young dams from 18 months to 2.5 years of age. One hundred and fifteen singleton- and twin-born female offspring born to either ewe-lamb (8 months at breeding) or adult ewe dams were maintained as one cohort under commercial New Zealand grazing conditions. Ewe live weights and body condition scores were recorded, as were ovulation rates at a synchronised breeding and number of fetuses present at pregnancy scanning. The live weight of ewes born to ewe-lambs were lighter (P<0.05) than those born to adult ewes at breeding and during their first pregnancy but not (P>0.05) at the weaning of their lambs. Twin-born ewes were lighter (P<0.05) than their singleton-born counterparts. There was no difference in corpora lutea number (P>0.05) at breeding or number of fetuses at pregnancy scanning. Lambs whose grand dam was a ewe-lamb were heavier at birth (P<0.05) but not at weaning (P>0.05) compared to those lambs whose grand dams was an adult ewe. This data suggests there are few negative impacts from selecting progeny born to ewe lambs as replacement ewes. However, before this hypothesis can be supported, lifetime data of these ewes needs to be collected.
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    The use of farm-management tools by New Zealand sheep farmers: Changes with time
    (New Zealand Society of Animal Production, 2016) Corner-Thomas, RA; Kenyon, PR; Morris, ST; Ridler, AL; Hickson, RE; Greer, AW; Logan, CM; Blair, HT
    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.