Cento e sessenta ovelhas, no terço final da gestação, foram distribuídas em delineamento de blocos completos casualizados, para avaliar os efeitos da diminuição da concentração de CNF na dieta pré e pós-parto, sobre a lactação e o desempenho das crias após o nascimento. As dietas experimentais foram compostas por 50% de volumoso (feno de \"coastcross\") e 50% de concentrado, sendo o milho o principal ingrediente utilizado na dieta com mais CNF e a casca de soja o principal ingrediente da dieta com reduzido CNF, correspondendo aos tratamentos M e CS, respectivamente. Foram avaliados o CMS e as concentrações de glicose, insulina e ácidos graxos não esterificados (AGNE), 3h após a oferta de alimento nos dias 21 e 7 antes do parto e imediatamente após a parição. No dia do parto foi avaliado o peso e o escore da condição corporal (ECC) das ovelhas. Da segunda à 12ª semana de lactação, 38 ovelhas e suas respectivas crias foram utilizadas para avaliar a lactação. Após a parição as ovelhas permaneceram nos tratamentos experimentais (M e CS) pré-parto e foram blocadas de acordo com a data do parto, o sexo e o número de crias. Uma vez por semana as ovelhas foram separadas de suas crias e ordenhadas mecanicamente. Três horas após a 1° ordenha, as ovelhas foram novamente ordenhadas e a produção de leite registrada. Também foram avaliados o CMS diário, o ECC, nas semanas 3, 6, 9, e 12 pós-parto, e as concentrações séricas de glicose, insulina e AGNE, 0 e 3h após o fornecimento das dietas, na 2ª, 4ª, 6ª, 8ª, 10ª e 12ª semanas de lactação. O efeito do tratamento materno sobre o desenvolvimento das crias foi avaliado através do peso ao nascimento, GMD e CMS durante o aleitamento. No confinamento, além do GMD e o CMS, foram determinados a eficiência alimentar e as características das carcaças ao abate. No final da gestação a dieta CS promoveu aumento do CMS e maior peso das fêmeas ao parto, assim como maior peso das crias ao nascimento. Entretanto, não houve alteração no ECC e nas concentrações de glicose, insulina e AGNE. Durante a lactação, não houve efeito das dietas na produção e composição do leite. Houve aumento na concentração de AGNE, às 3 h após alimentação, para o grupo CS sem diferença para as demais variáveis sanguíneas. Não houve diferença no desempenho dos cordeiros durante o aleitamento ou no confinamento. A diminuição de CNF da dieta de ovelhas pré-parto aumenta o CMS, resultando em maior peso ao parto, assim como maior peso das crias ao nascimento. Entretanto, no período pós-parto não altera o desempenho das crias e das ovelhas na lactação, mas aumenta a concentração de AGNE 3 h após a alimentação. / One hundred and sixty ewes, in the last third of gestation, were allotted in a randomized complete block design to determine the effects of lowering the concentration of NFC in the pre and postpartum diets on lactation performance and offspring growth. The experimental diets were composed of 50% roughage (coastcross hay) and 50% concentrate, with corn being the main ingredient used in the diet with high NFC and soybean hulls as the main ingredient of the diet with reduced NFC, corresponding to treatments C and SH, respectively. Dry matter intake (DMI) and the concentrations of glucose, insulin and non-esterified fatty acids (NEFA), 3h after feeding, in the days 21 and 7 prior and immediately after lambing. At lambing, ewes and lambs were weighed and ewe\'s body condition score (BCS) was recorded. From the second to the 12th week of lactation, 38 ewes and their offspring were used to evaluate lactation performance and lamb growth. After lambing, the ewes remained in the experimental pre-natal treatments (C and SH) and were blocked according to date of birth, sex and number of offspring. Once a week the ewes were separated from their lambs and mechanically milked. Three hours after the 1st milking, the ewes were again milked and the production was recorded. In addition it was determined the daily DMI, the BCS, in weeks 3, 6, 9, and 12 postpartum, and blood concentrations of glucose, insulin and NEFA, 0 and 3 hours after feeding, in the 2nd , 4th , 6th , 8th , 10th and 12th weeks of lactation. The effects of maternal diet on the growth of offspring were assessed by birth weight, ADG and DMI. During the feedlot, in addition to ADG and DMI, feed efficiency and carcass characteristics at slaughter were determined. In late gestation reducing NFC increased DMI and weight of ewes at parturition, as well as lambs birth weight. However, there was no change in BCS and in the concentrations of glucose, insulin and NEFA. During lactation, there was no difference in the ewe\'s milk production and lamb\'s growth. An increase in the concentration of NEFA, 3 hours after feeding, was observed for the SH group, with no difference for the other blood variables. Reducing pre-partum dietary NFC increases DMI, ewes lambing weight and lambs birth weight. However, in the postpartum period there was no change on ewe\'s lactation performance and lamb\'s growth, only an increase in the concentration of NEFA, 3h after feeding.

Orientador: Rafael Silvio Bonilha Pinheiro / Co-orientador: Antonio Fernando Bergamaschine / Co-orientador: Marcelo Andreotti / Banca: Cristiana Andrighetto / Banca: Ciniro Costa / Resumo: O objetivo com o trabalho foi avaliar o desempenho, digestibilidade, as características de carcaça e qualidade da carne de 24 cordeiros ½ Dorper ½ Santa Inês confinados recebendo dietas contendo silagem de sorgo exclusivo (SS), silagem de sorgo em consórcio com Panicum maximum cv. Tanzânia (SP), e silagem de sorgo com Urochloa brizantha cv. Xaraés (SU). O trabalho de pesquisa foi realizado na Fazenda de Ensino, Pesquisa e Extensão, no Setor de Ovinocultura da Faculdade de Engenharia de Ilha Solteira (FEIS/UNESP). Os animais foram alojados em baias individuais de 1 m2 e abatidos aos 30 kg de peso corporal. O delineamento experimental foi o de blocos casualizados com três tratamentos denominados por SS, SP e SU, como critério de bloco foi utilizado o peso corporal dos animais. As dietas foram compostas com relação volumso:concentrado de 60:40. O ganho de peso durante o estudo foi de 8,85; 7,78; e 8,16 kg para as dietas SS, SP e SU, respectivamente, não diferindo entre si (P>0,05). O tratamento SU obteve o menor valor de custos variáveis R$ 944,10 e a maior margem bruta total foi apresentada com a dieta contendo silagem de sorgo exclusivo (R$ 156,15). As características de carcaça não obtiveram diferenças significativas (P>0,05) para as variáveis de rendimento de carcaça quente e fria, perdas por resfriamento, porcentagens de cortes em relação ao peso da meia carcaça direita, espessura de gordura e área de olho de lombo. Para a qualidade da carne, o SU diferiu (P<0,01) dos demais com menor média (9,01) para intensidade de amarelo (b*). As perdas por cocção (PPC) diferiram (P<0,05), com maior média para o tratamento SU (39,7%) e menor para SP (36,20). A força de cisalhamento (FC) diferiu (P<0,05) com menor valor para SU (3,80 kgf/cm2) em relação aos tratamentos SS e SP. Os melhores resultados de desempenho obtidos foram com o tratamento SU, com melhor conversão alimentar (4,84 kg de ganho/kg de MS) e maior consumo de ... / Abstract: The objective of this work was the performance, digestibility, carcass characteristics and meat quality of ½ Dorper ½ Santa Ines lambs in feedlots, fed with diets containing sorghum silage exclusive (SS), sorghum silage intercropped with Panicum maximum var. Tanzania (SP), and sorghum silage with Urochloa brizantha var. Xaraés (SU). The research was conducted at the Farm for Teaching, Research and Extension in the Sheep Sector of the College of Engineering of Ilha Solteira (FEIS/UNESP). The animals were housed in individual pens of 1 m2 and slaughtered at 30 kg of body weight. The experimental design was randomized blocks with three treatments; SS, SP and SU; as a criterion of block the animals' body weight. The diets were composed by roughage:concentrate ratio of 60:40. The weight gain during the study was 8.85, 7.78, and 8.16 kg for SS, SP and SU diets, respectively, did not differ from each other (P>0.05). The SU treatment had the lowest amount of variable costs R$ 944.10 and higher total gross margin was presented with the diet containing sorghum silage exclusive (R$ 156.15). Carcass characteristics were not different (P> 0.05) for hot and cold carcass yield, refrigeration losses, proportions of cuts and loin eye area. For meat quality, the treatment SU differed (P< 0.01) from the others, with lower average (9.01) for yellow intensity (b*). Cooking losses (CL) were significant (P<0.05), with higher mean for treatment SU (39.7 %) and lowest for SP (36.20 %). The shear force (SF) differed (P<0.05), with lower value for SU (3.80 kgf/cm2) from SS and SP. The greater performance results were obtained with SU treatment, with superior feed conversion (4.84 kg of gain / kg of Dry matter) and higher dry matter intake (90.10 g/kg0.75/day). The experimental diets did not influence variables on carcass characteristics of confined lambs. The SU treatment afforded to lamb meat lowest SF, lower b* value in the flesh, but a larger CL when compared ... / Mestre

Orientador: Edson Ramos de Siqueira / Coorientador: Simone Fernandes / Banca: Vânia Maria Vasconcelos Machado / Banca: Sirlei Aparecida Maestá / Resumo: Este estudo teve como objetivo avaliar a idade à puberdade, a dinâmica corporal e o desempenho de cordeiras Bergamácia submetidas a dietas para baixa e alta velocidades de crescimento, até 1 ano de idade. Vinte cordeiras foram mantidas confinadas (duas por baia) durante todo o período experimental recebendo dois tipos de dietas formuladas para obtenção de ganho de peso médio diário: 1) Baixo (180 gramas); 2) Alto (300 gramas). O experimento foi dividido em duas fases, sendo a primeira o período compreendido até as cordeiras atingirem 30 kg; e a segunda fase a partir de 30 kg até 1 ano de idade. Para avaliação da dinâmica do desenvolvimento corporal, a cada 14 dias os animais foram pesados, determinado o escore de condição corporal e registradas medidas biométricas. A partir do 5º mês de idade foi introduzido, em cada grupo experimental, um macho vasectomizado para realizar a detecção do estro e determinar a idade à puberdade e o intervalo entre os dois primeiros estros de cada cordeira. Foram encontradas diferenças (P˂0,05) entre os tratamentos para ganho de peso médio diário, escore de condição corporal e para as medidas biométricas. Não houve diferença (P>0,05) para idade à puberdade. Verificou-se que os tratamentos baixo e alto proporcionaram desempenhos adequados, porém não revelaram diferentes respostas a idade à puberdade. A dieta para alta velocidade de crescimento proporcionou pesos superiores e melhor escore de condição corporal nas duas fases experimentais / Abstract: This study aimed to evaluate the age at puberty, body dynamics and performance of Bergamasca lambs submitted to diets for low and high growth rates, up to 1 year old. Twenty lambs were kept confined (two per stall) throughout the experimental period getting two types of diets to obtain average daily weight gain: 1) Low (180 grams) 2) High (300 grams). The experiment was divided into two stages, the first was the period until lambs reached 30 kg, and the second phase with the lambs weighting from 30 kg until they reach one 1 year old. To assess the dynamics of body development, every 14 days the animals were weighed, the body condition score was determined and biometrics measurements were registered. From the 5th month of age was introduced in each experimental group, a vasectomized male to perform the detection of estrus and to determine the age at puberty and interval between the first two estrous of each lamb. Differences were found (P˂0.05) among treatments for average daily weight gain, body condition score and biometric measurements. There was no difference (P>0.05) for age at puberty. It has been found that low and high treatments yielded adequate performance, but did not show different responses in age at puberty. A high growth rate diet yielded higher body weights and better body condition score in both phases / Mestre

O experimento foi conduzido com o objetivo de avaliar o efeito de quatro sistemas de alimentação sobre o desempenho e características da carcaça na terminação de cordeiros Corriedale. Foram utilizados 120 cordeiros com dez meses de idade, castrados, com peso inicial médio de 28,2±0,800 kg e escore de condição corporal de 2,65±0,2. Os tratamentos avaliados foram: PAS: pastagem; PAS0,6: pastagem + 0,6% do peso vivo (PV) de suplemento; PAS1,2: pastagem + 1,2% PV de suplemento e confinamento (CONF): confinamento. Foi utilizado um delineamento completamente cazualizado, onde o animal foi a unidade experimental. Os cordeiros terminados em CONF apresentaram ganhos médios diários de 105, 73 e 31 gramas superiores aos cordeiros terminados em PAS, PAS0,6 e PAS1,2, respectivamente (P<0,05). Não houve diferença no rendimento de carcaça dos animais dos tratamentos CONF (47,78%) e PAS 0,6 (46,20%), os quais foram superiores aos apresentados pelos animais dos tratamentos PAS (44,36%) e PAS 1,2 (45,59%). Os teores de gordura subcutânea dos animais PAS0,6 (4,39%) e dos animais em CONF (4,01) foram superiores aos apresentados pelos animais com PAS1,2 (2,75%) (P<0,05). A percentagem de músculo nas carcaças dos animais suplementados (55,96%) foram superiores aos valores apresentados pelos animais em pastejo (54,95%) e em confinamento (53,65%) (P<0,05). A percentagem de músculo nas carcaças dos animais suplementados (55,96%) foram superiores aos valores apresentados pelos animais em pastejo (54,95%) e em confinamento (53,65%) (P<0,05). A percentagem de osso nas carcaças diminuiu com o aumento no nível de suplementação (P<0,05). O sistema de alimentação afetou a tipificação de carcaças, sendo que os animais terminados em PAS0,6 e PAS1,2 apresentaram níveis moderados na gordura de cobertura enquanto as carcaças dos animais terminados em CONF apresentaram excessiva cobertura de gordura (P<0,05). A terminação de cordeiros pesados em sistemas de alimentação em pastagem com níveis moderados de suplementação permitem obter pesos e qualidades de carcaça de acordo com as exigências do Mercado Europeu. / The trial was lead in order to evaluate the effect of four feeding systems on the performance and characteristics of the carcass of finishing Corriedale lambs. One hundred and twenty ten-month-old castrated lambs, 28,2 ± 0,800 kg of average initial live weight and body condition score 2,65±0.2 were used. Animals grassed an improved native pasture with legume specie (Lótus corniculatus cv INIA Draco) and they were assigned to four treatments: PAS: pasture; PAS0,6: pasture + 0,6%BW of supplement; PAS1,2: pasture + 1,2% BW of supplement and CONF: drylot. Completely random designs were used, and an animal was an experimental united. Average daily gains on CONF were 105, 73 and 31 grams higher than those finished in PAS, PAS0,6 and PAS1,2, respectively. There were differences of carcass yield for CONF treatments (47,78 %) and PAS 0,6 (46,20%), which were higher than PAS (44,36%) and PAS1,2 (45,59%) treatments. Subcutaneous fat tissue of animals fed treatments PAS0,6 (4,39%) and CONF (4,01) were larger than those fed treatments PAS1,2 (2,75%) (P<0,05). The e percentage of muscle in the carcasses of supplemented animals (55,96%) was larger than those raised without supplementation (P<0,05). The feeding system affected the conformation and termination. Animals finished in PAS0,6 and PAS1,2, had moderated levels of subcutaneous fat tissue, while carcasses of animals finished on drylot had deeper fat covering (P<0,05). Lambs finishing, on pasture with moderate supplementations levels, fitted live weights and carcass characteristics demanded for the European market.

Orientador: Maria Lucia Gomes Lourenço / Resumo: Os objetivos do presente estudo foram descrever a avaliação cardíaca pré-natal em ovinos, uma vez que durante a gestação e no período neonatal ocorre uma série de modificações fisiológicas. O diagnóstico de gestação em ovelhas incorpora valor econômico sendo que, quando realizado precocemente, é útil para adequação do manejo nutricional, além disso, os dados obtidos podem servir de base em pesquisas translacionais, já que os parâmetros cardíacos na espécie ovina assemelham-se aos do neonato humano. Foram avaliados os aspectos clínicos, ecocardiográficos e eletrocardiográficos (VFC) de 10 ovelhas da raça Dorper, durante cinco meses de gestação e 24 horas após o parto, sendo os cordeiros também avaliados no mesmo período referido, sete, 14, 21, 30 dias, dois, três e quatro meses após o nascimento. Os parâmetros ecocardiográficos maternos modificaram-se durante a gestação havendo aumento da espessura do SIVd a partir do 3° mês, aumento do DIVEs e DIVEd no 2° e 3° mês. A FE elevou-se com o avançar da gestação e o tamanho do AE a partir do 2° mês. Não houve diferença para os parâmetros ecocardiográficos fetais, exceto para o diâmetro do VE que apresentou maior dimensão no quinto mês gestacional. No período neonatal o intervalo RR elevou-se a partir de 21 dias. Houve diferença nos períodos etários quanto aos índices LF (n.u.), que reduziu a partir de 21 dias de idade e para o índice HF (n.u.) o inverso ocorreu. Os parâmetros ecocardiográficos modificam-se conforme a gestação progri... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objectives of the present study were to describe prenatal cardiac evaluation in sheep, since during pregnancy and the neonatal period a series of physiological changes occurs. The diagnosis of pregnancy in sheep incorporates economic value and, when performed early, is useful for the adequacy of nutritional management. In addition, the data obtained may serve as a basis for translational research, since the cardiac parameters in sheep are similar to of the human neonate. The clinical, echocardiographic and electrocardiographic (HRV) aspects of 10 Dorper ewes were evaluated during five months of gestation and 24 hours after calving. The lambs were also evaluated during the same period, seven, 14, 21, 30 days, two, three and four months after birth. Maternal echocardiographic parameters changed during pregnancy, with increased thickness of the SIVd from the third month, the DIVEs and DIVEd at the second and third month. The EF increased with advancing pregnancy and the size of the AE from the second month. There was no difference for fetal echocardiographic parameters, except for the LV diameter that was larger in the fifth gestational month. In the neonatal period, the RR interval increased from 21 days. There was a difference in age for LF (n.u.), which decreased from 21 days of age, and for HF (n.u.), the opposite occurred. Echocardiographic parameters change as gestation progresses in sheep. Fetal echocardiographic evaluation allows the identification of fetal viability... (Complete abstract click electronic access below) / Doutor

I evaluated some of the factors affecting livestock distribution by conducting experimental (Chapters II and III) and observational (Chapter IV) studies. In Chapter II, I described the effect of locations of familiar foods and social interactions on choice of feeding location by lambs. Lambs were exposed to a pasture as subgroups of strangers and companions with different dietary habits (i.e., three lambs that preferred milo with three lambs that preferred wheat). Milo was placed on one end and wheat on the other, about 100 m apart. Strangers typically fed in different locations, reflecting dietary preferences. Conversely, companions fed in both single subgroups and in separate subgroups because both social interactions and dietary preferences affected choice of feeding location. The objective of Chapter III was to evaluate the effect of experience with a pasture on choice of feeding location. Lambs with different levels of familiarity with the pasture were exposed as subgroups with different dietary habits. Lambs familiar with the pasture typically fed in separate locations, reflecting dietary preferences. Lambs naive to the pasture always fed in one subgroup and consumed both foods because social interactions overrode dietary preferences. Results in Chapter IV describe cattle observations on a 1,030-ha grazing allotment. Cattle home ranges were similar in location (i.e., site fidelity) between 1990 and 1991, even though home ranges increased in size and (or) shifted in location in response to water availability. Moreover, forage availability did not account for changes in home range size or location. Site fidelity probably developed because of experiences early in life while foraging with mother and (or) peers. Managers may be able to improve distribution by manipulating foraging experiences. Placing familiar foods/supplements in underutilized areas, controlling the amount of experience livestock have with different habitat types, and culling animals that spend a disproportionate amount of time in riparian zones may improve · distribution. Herding could also improve distribution. Herding integrates social interactions and experience with foods by controlling the exposure of social groups to particular foods and habitats. Nevertheless, livestock may still spend considerable time in riparian zones unless other watering points are available.

Ram lamb epididymitis, a serious reproductive disease of sheep, is caused principally by bacteria belonging to the genera Haemophilus and Actinobacillus. Six bacteria were studied: the American Type Culture Collection (ATCC) of Actinobacillus seminis (ATCC 15768), ATCC of Actinobacillus actinomycetemcomitans (ATCC 29522), field isolates of A seminis (86722 and 4101) and field isolates of Actin obacillus- like bacteria (Y136 and D107). The objectives of this study were to quantitate the adhesion of these 6 bacteria to bovine kidney epithelial cells (BKECs) and ram epididymal epithelial cells (REECs), evaluate the effect of rabbit polyclonal antibody prepared against ATCC 15768 (PoAb 15768) on bacterial adherence to BKECs and REECs, and partially characterize the adhesins present on these bacteria. In a bacterial adhesion assay (BAA), strain and species differences were noted. The number of bacteria adhering to each BKEC ranged (rom a low of 4.27 ± 1.00 (Actinobacillus-like 0107) to a high of 31.84 ± 2.00 (A seminis 86722). The number of bacteria adhering to each REEC ranged from a low of 3.05 ± 0.34 (Actinobacill us-like 0107) to a high of 21.61 ± 2.03 (Actinobacillus like Yl36). In a bacterial inhibition assay (BIA), PoAb 15768 inhibited the adhesion of ATCC 15768 to both BKECs and REECs by 5%. This same antiserum inhibited the adhesion of ATCC 29522 to BKECs by 14.5% and to REECs by 22%. The inhibition of A seminis 86722 adherence to BKECs and to REECs was less than 14% and 35%, respectively. For A seminis 4101, Actinobacillus-like Y136, and Actinobacillus-like 0107, PoAb 15768 failed to prevent adhesion to either BKECs or REECs. When the 6 bacteria were analyzed by autoradiography, 2 (Actinobacillus-like 0107) to 8 (ATCC 29522) potential adhesins were identified. However, the pathogenicity has not been firmly established for many Actinobacillus species and Actinobacillus-like bacteria. The potential adhesins identified in this study were not unequivocally confirmed as bacterial adhesins. An in vit ro model may facilitate the recognition of potential adhesins used by Actinobacillus species and Actinobacillus-like bacteria and may eventually lead to the development of an efficacious bacterin to prevent epididymitis in ram lambs at risk.

Baiting with sodium monofluoroacetate (1080) to protect lambs (Ovis aries) from red foxes (Vulpes vulpes L.) has become more frequent in NSW and other parts of Australia during the last 10 years despite the lack of reported evidence evaluating the effects of fox baiting on lamb survival. NSW Agriculture has developed fox control recommendations aimed at minimising impact, but these guidelines have not been tested experimentally. Defining the extent of a pest problem and the effectiveness of pest control are key components of a strategic approach to vertebrate pest management as it is the damage of pests that justifies their control. This thesis describes an experimental evaluation of the recommended practice of fox control in NSW. The effects of three levels of fox control were tested in the experiment; no treatment, baiting once a year before lambing (the recommended practice) and baiting three times a year (thought to be the maximum farmers would instigate). Each treatment had two replicates. No previous manipulative experiment using synchronous controls and matched replicates has been undertaken to test the effects. The study quantifies the level of fox predation on healthy lambs and the level of predation on lambs that had other causes including illness and mismothering contributing to this fox predation. It also examines the response of the fox population, lamb predation and lambing outcomes to different levels of fox control. The cost effectiveness of fox control is examined in relation to lamb predation and an investigation of the optimum level of fox control is begun. The experiment also provides the first chance to consider the examination of multiple response variables and the scale of field ecology experiments required to recognise a significant response and avoid a Type II error due to between replicate variability even with tightly controlled site selection criteria to standardise experimental sites, and with the synchrony of experimental control and treatment surveys. The study occurred on five sheep properties near Boorowa (34°28'S, 148°32'E) and Murringo (34°18'S, 148°3 1'E) in south-eastern Australia. The terrain was undulating to hilly with a maximum elevation of 660 m above sea level. The main agricultural enterprises in the district are Merino wool, fat lamb and beef cattle production and winter cereal cropping. The native vegetation of Eucalyptus woodland has been mostly cleared, though remnant patches occur. Most of the area is now sown with pasture of Phalaris tuberosa, Lolium spp. and clover Trifolium spp.. The experimental properties grazed self-replacing Merino flocks, primarily for wool production, so lamb survival was vital to the economic operation of the farm. Over 50 selection criteria including lamb survival rates, ewe fertility and bloodline, sheep management practices, climate and habitat features that affect lamb survival, past fox control practices and prey species were used to select sites Sites were representative of most sheep farming properties in the region, but were also extremely similar in factors that affected fox abundance and ewe and lamb survival, thus minimising variation between replicate sites. The manufactured meat baits used to poison foxes contained 3 mg of sodium monofluoroacetate (compound 1080). A replacement baiting program was carried out in 1995 and 1996. Fox control programs were carried out over the experimental units and adjacent buffer zones covering approximately two fox territories, approximately 6km2, around the lambing paddock under study. The recommended fox control practices described by NSW Agriculture also included neighbouring farmers taking part in an extended group baiting program. In all the area baited at varying intensities totalled 3400 km2. Synchronised lambing with neighbours was a further recommended practice to reduce fox predation and was carried out on these sites. Lambing occurred during a six to eight week period in late winter on all sites, a practice known as 'spring lambing', and on many surrounding properties so a surplus of lambs was available to foxes over a relatively short time. The benefits of fox control were measured directly as enhanced lamb survival derived from differences in lamb marking rates between ultrasounded flocks of approximately 1000 ewes and the predation of lambs was measured from over 2000 lamb carcases post-mortemed in 1994, 1995 and 1996. A mean of 138 lambs were expected at ultrasounding from 100 ewes and 113 lambs per 100 ewes were alive at lamb marking. There was no significant (P>0.05) effect of fox control on lambing performance (the number of lambs per 100 ewes that lambed) Fox predation was inferred as the cause of lamb death in a minimum of 0.8% and a maximum of 5.3% of lamb carcases during 1995 and 1996. There was a significant (P<0 05) effect of fox control on the minimum possible percentage of lamb carcases classified as healthy lambs killed by foxes, with the percentage declining from 1.50% (no fox control), to 0.90% (fox control once per year) to 0.25% (fox control three times per year). There was also a significant (P<0.005) effect of fox control on the maximum possible percentage of lamb carcases classified as healthy lambs killed by foxes with the percentage declining from 10.25% (no fox control), to 6.50% (fox control once per year) to 3.75% (fox control three times per year). The observed results were used to estimate the number of treatment replicates needed to be confident of detecting an effect of predator control on lamb marking performance. The estimated numbers were very high if small effects were to be detected. No significant correlation between the fox density and the minimum and maximum possible number of lambs carcases classified as killed by foxes was found. Bait uptake was monitored as were the costs of fox control.

Bibliography : leaves 120-133. Defines the sources of reproductive wastage in FecB FecÊ Booroola Merino x South Australian Merino ewes and examines factors associated with the survival of embryos, fetuses and lambs with the aim of improving net reproduction efficiency. Experiments were conducted to define the problem; to examine factors affecting embryonic and fetal loss; and, to investigate factors influencing wastage at lambing.

Bibliography: leaves 281-316. Presents investigations on pubertal development in South Australian merino ram lambs and examines the effect of active and passive immunizations against oestradiol-17ℓ or oestrone on testicular maturation.