Le pâturage, principal mode d’alimentation en zone tropicale, est souvent dévalorisé car il est associé à des performances animales jugées insuffisantes, et peut avoir des effets néfastes sur l’environnement. Même si l’alimentation à l’auge permet de meilleures productions, ce mode de conduite présente également des inconvénients, en termes d’investissements, de rentabilité économique, d’impact des rejets sur l’environnement et de qualité des produits. Une intensification de la conduite au pâturage semble donc une voie d’avenir, mais nécessite une meilleure connaissance de ce mode de conduite et de ses conséquences sur l’alimentation et les performances des animaux. Il apparait également nécessaire de comparer l’élevage au pâturage et à l’auge sur des critères homogènes, en dissociant les composantes de ces modes de conduite.L’objectif de la thèse est d’évaluer et de comparer la conduite au pâturage et la conduite hors sol, en tenant compte également de la distribution ou non de concentré, sur l’alimentation, la croissance, les caractéristiques d’abattage et la consommation d’eau. Dans un premier temps, nous avons étudié au cours d’une expérimentation, les effets de ces deux modes de conduite sur la croissance, les caractéristiques d’abattage et de carcasse de taurillons Créoles abattus à deux âges (précoce vs tardif). Les taurillons à l’auge avaient une croissance plus rapide, des poids de carcasse plus élevés, ainsi que des carcasses plus grasses. Nous avons observé qu’abattre plus tardivement au pâturage (17 et 21 mois vs 14 et 17 mois à l’auge), permettait d’atteindre des poids finaux similaires à ceux obtenus à l’auge et des carcasses de meilleure qualité, plus riche en muscle. Nous avons expliqué la majorité de nos résultats par les effets combinés des modes de conduite et de l’alimentation et avons voulu étudier leurs effets respectifs. Dans un second temps, l’étude des effets du mode de conduite a été faite dans un premier temps, par le biais d’une méta-analyse. Les performances des animaux à l’auge étaient meilleures qu’au pâturage, mais ces effets dépendaient de la stratégie de complémentation. De cette méta-analyse est également apparu le manque d’études auge vs pâturage sur l’alimentation et à ration égale. Afin d’étudier les effets respectifs du mode de conduite et de la stratégie de complémentation, un dispositif analytique avec des taurillons élevés à l’auge et au pâturage complémentés ou non avec du concentré a été mis en place. Dans un premier temps, une étude méthodologique menée grâce à ce dispositif nous a permis d’identifier que la SPIR permettait la meilleure estimation de la dMO, l’OMI et la MODI au pâturage. Les résultats de l’étude analytique ont montré que les animaux au pâturage utilisaient mieux leur alimentation pour leur croît que ceux à l’auge et la stratégie de complémentation influençait davantage ces variables que le mode de conduite. Avec une stratégie de complémentation appropriée, les animaux au pâturage peuvent atteindre des performances similaires à celles obtenues à l’auge. / Grazing, main way of feeding ruminants in the tropics, is often undervalued because it is associated with animal performance deemed insufficient, and may have adverse effects on the environment. Even if stall feeding allows better production, this way of feeding has drawbacks in terms of investment, profitability, impact of emissions on the environment and product quality. Intensification of grazing seems a way forward, but requires a better understanding of this way of feeding and its impact on feeding and animal performance. It also appears necessary to compare grazing and stalls feeding on homogeneous criteria, separating the components of these modes of management.The aim of the thesis is to evaluate and compare stalls and pasture feeding environment, taking into account also the distribution or not of concentrate on feeding, growth, slaughter characteristics and water consumption. At first , we studied in an experiment , the effects of these two feeding systems on growth, slaughter and carcass characteristics of Creoles bulls slaughtered at two ages (early vs. late ). Bulls fed in trough grew faster, had greater carcass weight and fatter carcasses. We observed that a later slaughter of grazing animals (17 and 21 months vs. 14 and 17 months in stalls), allowed to reach final weights similar to those obtained in stalls and carcasses richer in muscle. We explained most of our results by the combined effects of feeding environment and complementation strategy and wanted to study their effects. In a second step, the study of the effects of feeding environment was made in first instance, through a meta-analysis. Stalls fed animals had greater performances than pasture fed ones, but these effects depended on complementation strategy. This meta-analysis also highlighted the lack of knowledge on intake and digestibility at pasture, which is a limitation on attempts to compare with measurements carried out in trough-fed animals. To investigate the relative effects of feeding environment and complementation strategy, we conceived an analytical trial with Creole bulls reared in stalls and at pasture, supplemented or not with concentrate. First of all, this analytical trial was the support of a methodological study, which identified that the NIRS method allows the best estimate of the OMD, OMI and DOMI at pasture. The analytical trial showed that grazing animals had better feed efficiency feed for their growth than stall fed ones and complementation strategy influenced more these variables than feeding environment. With an appropriate strategy for complementation, grazing animals can achieve similar performance to those obtained at the trough.

Doctor of Philosophy / Department of Animal Sciences and Industry / Megan Rolf / In the future, water may not be as readily available due to an increase in competition from a growing human population, wildlife, and other agricultural sectors. To better understand water demands in the beef industry, water intake has to be accurately measured. It also critical to understand if water intake is a heritable trait and to determine its relationship to other production traits. This dissertation examines the number of days to accurately measure water intake in beef cattle, how to predict water intake in beef cattle using individual intakes, and estimates genetic parameters for water intake, dry matter intake (DMI), average daily gain (ADG), water efficiency measures, feed efficiency measures, and carcass traits. Study 1 investigates the test duration required to accurately measure water intake. Water intakes were collected over 70 d and shortened test periods (7 day intervals) were correlated with the full 70 day test to determine the minimum number of days required to accurately measure water intake. Water intake can be collected over a 35 to 42-day test period, with a minimal decrease in accuracy. Study 2 developed a water intake prediction equation that included different weather variables and average daily temperature (TAVG), average relative humidity (HVAG), solar radiation (SRAD), and wind speed (WSPD). Water intakes and feed intakes on individual animals were collected over a 70-day period along with (TAVG), (HVAG), (SRAD), (WSPD) for each day. Five different prediction equations were developed: summer, winter, slick bunk feed management, ad libitum feed management, and overall. All models included variables of DMI, metabolic mid test weight, TAVG, HAVG, SRAD, and WSPD, with R-squared values ranging from 0.34 to 0.41. Study 3 investigated the relationships between water intake and DMI, ADG, and water and feed efficiency traits. Variance components and genetic correlations were estimated using single-step genomic best linear unbiased prediction (GBLUP), incorporating genotypes on approximately 150,000 single nucleotide polymorphisms. Water intake was moderately heritable (0.39) and had moderate genetic correlations with DMI and residual feed intake, high genetic correlations with residual water intake, water to gain ratio, and feed to gain ratio, and had a low genetic correlation with ADG. Study 4 investigated the relationship between water intake and carcass traits. Single-Step GBLUP was used to estimate variance components and genetic correlations between water intake and carcass traits. Similar to study 3, water intake was moderately heritable (0.42). Water intake was moderately correlated with hot carcass weight (0.38), back fat (0.36), yield grade (0.29), and final body weight (0.29), but had a low genetic correlation with longissimus muscle area (0.08) and marbling (0.17). More research must be done to determine the relationships between water intake and other economically important traits in beef cattle and to better understand how environment and genetic background affect water intake. Improvements in water efficiency could decrease the amount of water cattle consume and assist producers in managing on-farm water resources during times of water scarcity.

Salmonella species is the etiologic agent of salmonellosis, which is a zoonotic infection that is characterized by diarrhea and systemic infection. Contaminated foods are usually the vehicles of Salmonella transmission along the food supply chain. Asymptomatic food production animals and effluents also contribute to contamination of meat. Antimicrobials have contributed significantly to treatment of salmonellosis. However, uncontrolled antimicrobial use is among the causes of antibiotic resistance, which results in treatment failure. The aim of this research study was to determine the extent of Salmonella spp contamination during the cattle slaughtering process in South African rural abattoirs (n = 23), water and cattle feaces. In addition, the aim was to determine antimicrobial resistance profiles of the Salmonella spp isolates. The specific objectives were: i) to establish the occurrence and distribution of Salmonella spp on cattle carcasses, hides, and intestinal contents and environmental samples using classical microbiology and molecular techniques; ii) to determine the Salmonella serovars using serotyping; and iii) to determine antimicrobial resistance patterns and multidrug resistance among the Salmonella isolates using the Kirby-Bauer disc diffusion method. Materials and Classical microbiology techniques were used to analyze cattle faeces (n = 400), hides (n = 67), intestinal contents (n = 62), carcass sponges (n = 100), and water from the abattoirs (n = 75) for the presence of Salmonella spp. Further confirmation of the Salmonella isolates was done using Polymerase Chain Reaction whereby the invA gene was targeted. A total of 92 Salmonella spp isolates were recuperated. The 92 Salmonella were serotyped as described in the White-Kauffmann-Le Minor scheme. The 92 Salmonella spp isolates were further subjected to antimicrobial susceptibility examination towards the following antimicrobials: ampicillin (10μg), cefotaxine (30μg), kanamycin (30μg), oxytetracycline (30μg), and enrofloxacin (5μg) by using the Kirby-Bauer disk diffusion procedure. All the isolates carried the invA genes. The average Salmonella spp occurrence on carcasses, hides, and intestinal contents was 35.37% (n = 81). Eleven of the faecal samples (2.75%) tested positive for Salmonella spp. The Salmonella serovar that occurred more frequently was S. Enteritidis. Different serovars that were recognized on carcasses were not automatically found on the hides and intestinal contents. The incompatible frequency of the different Salmonella serovars on carcasses, intestinal contents and hides means that in addition to carriage on hides and in intestinal contents, new external causes that did not form part of this study also play a vital role concerning carcass contamination. Most Salmonella spp (n = 66; 71.7%) isolates were resistant to a minimum of one antimicrobial with main resistance detected towards oxytetracycline (51.90%). This emphasizes on the call for wise antimicrobial use at some stage in animal production and strict sanitation for the duration of slaughtering. Briefly, cattle slaughtered in South African rural abattoirs harboured different types of Salmonella serovars that were resistant to antimicrobials, which could be a public health risk and danger. The outcome should support policymakers with determining the effectiveness of existing sanitary measures during cattle slaughtering in rural abattoirs, which is vital from socio-economic, public health, and epidemiological perspectives. / College of Agriculture and Environmental Sciences

The aim of the study was to determine the quality of South African lamb, particularly the carcass, nutrient and sensory attributes. To this end the cut composition of SA lamb carcasses with different fat scores was determined and cuts suitable for trimming were identified. Sixty four grain fed Dorper lambs were divided randomly into three slaughter groups of 30, 36 and 42 kg, respectively. After slaughter, electrical stimulation (how much/long) and chilling (how long/temp) the carcass sides were subdivided into seven wholesale cuts. Each cut was dissected into meat, bone and subcutaneous fat (SCF) in order to determine the physical composition per cut and for the whole carcass. It was found that the percentages total fat in the carcass increased with 15.5 % in subcutaneous fat over the five fat classes. In order to determine and compare the raw and cooked nutrient composition of shoulder, loin and leg cuts of Dorper and Merino lamb carcasses of the A age class of fat class 2 (± 7 % SCF) from three main production areas in South Africa were analysed. Samples were analysed both raw (left side cuts) and cooked (right sides) using accredited methodologies for nutrient content namely proximate composition, vitamin B and minerals. There was no significant difference in the iron and zinc values between the cooked cuts. Results showed differences in both trace elements and B vitamins among different cooked cuts, although the differences were not statistically significant. Cooked SA lamb (A age class, fat class 2) contains an average of 60.5 % less total fat and 5.28 % less protein, resulting in 1891 kJ less per 100 g edible portion energy, if compared to the previous values in the food composition tables. Quantitative descriptive sensory analyses were performed by a trained panel on the M. longissimus lumborum (loin) from lambs of the same age. Aroma intensity, initial impression of juiciness, first bite, sustained impression of juiciness, muscle fibre and overall tenderness, amount of connective tissue (residue), overall flavour intensity and off-flavour intensity were measured, as well as cooking related measurements and resistance to shear. With the exception of juiciness, the results in this study showed that contrary to expected carcass fatness (in the same age over five fat classes), as portrayed in the South African Classification system, does not have a significant effect on the sensory qualities of M. longissimus lumborum (loin) from lambs of the same age. This investigation provides important scientific insight into the physical, nutrient and sensory quality of South African lamb. The results obtained show that subcutaneous carcass fat that increased significantly with an increase in fat class can be trimmed to represent leaner cuts to the discerning consumer. This study found unique values for South African lamb cuts, almost 40 % lower in fat content than the previously-believed-to-be-accurate values, as published by the Medical Research Council for health workers. Contrary to expected it was found in this study that increased fatness did not improve lamb tenderness as popularly believed in the United States. Therefore, the study justifies greater scope for further research into all these aspects, as it provides valuable information for the Red Meat Industry. / Thesis (PhD(Consumer Science))--University of Pretoria, 2008. / Consumer Science / PhD / unrestricted

The aim of this study was to evaluate and compare the influence of conventional and Kosher slaughter techniques in cattle on carcass and meat quality parameters. The conventional slaughter was done using a pneumatic captive bolt gun to stun the animals before sticking, while Kosher slaughter was done by sticking the animals and then stunning them with a 0.22 calibre cash special captive bolt gun, 20 seconds later. The animals (n=311) were randomly assigned into 4 treatment groups, namely; slaughter method (SM) (main group, sub-divided into: conventional slaughter technique (CST) and Kosher slaughter technique (KST)); electrical stimulation (ES), sub-divided into: electrically stimulated (ES) and non-stimulated (NES); gender (G), sub-divided into: male (M) and female (F); fat code (FC), sub-divided into: FC-2 and FC-3 (i.e. lean to medium fatness). The quality attributes evaluated were blood loss (BL), drip loss (DL), cooking loss (CL), presence of blood in the trachea (BLT), blood splash in the lungs (BS), shear force (SF), colour (L*, a* and b*), pH and temperature profile over 24 hours and the effect of subcutaneous fat thickness (SCF). Animals were mainly steers in the “A” age group with an average slaughter weight of about 400 kg. Different crossbreeds of Bonsmara, Brahman and Nguni cattle were used, which is typical of cattle slaughtered in South Africa. Blood loss, blood in trachea and blood splash were evaluated using 311 animals (CST, n=141; KST, n=170) but for the other parameters, smaller numbers were used because of the hectic nature of the trials. Evaluation of BL, BLT and BS were done in the abattoir and pH and temperature readings were also taken at 45 mins, 3, 6, 12 and 24 hrs post-mortem between the 10th and 11th rib on the m. longissimus dorsi which was where the carcasses were sampled for the meat quality analyses. The results of this study revealed that there was no significant difference (p> 0.05) in % blood loss between the conventional and the Kosher group but the conventionally slaughtered group had a slightly higher bleed-out. Fat code had a significant (p= 0.0475) influence on %BL, with FC-2 (2.42%) group bleeding out slightly more than FC-3 (2.24%). For % drip loss, there were no significant differences (p> 0.05) between all the treatment groups except for fat code (p= 0.0242), with FC-3 (2.95%) samples exuding more water than FC-2 (2.42%) meat samples. In terms of % cooking loss, there was a significant difference (p= 0.0004) between the slaughter methods, with meat samples from the conventional method (22.11%) exuding more water than the meat from Kosher group (18.16%). For blood in trachea, there was a highly significant difference (p< 0.0001) between the slaughter methods, with the Kosher-slaughtered animals having significantly more blood in the tracheas than the conventional group. Similarly, for % blood splash, the Kosher-slaughtered group also had a significantly (p< 0.0001) higher amount of splash than the conventional group. In terms of shear force, analyses showed significant difference between the SM with the Kosher meat (42.99) appearing more tender (p= 0.0005) compared to the meat from conventionally slaughtered animals (53.54). Electrical stimulation also had a significant influence, with meat from the ES group (43.27) being significantly (p< 0.0001) more tender compared to the NES group (61.15). For subcutaneous fat thickness, there were no significant differences (p> 0.05) in all the treatments save for fat code, with FC-3 group (6.38) having thicker fat cover (p= 0.0004) than FC-2 (4.44) which was anticipated. In terms of colour, there was a significant difference (p< 0.0001) between slaughter methods for the L* value (lightness). Meat samples from the Kosher-killed animals (46.08) were lighter than the conventionally killed ones (35.40). Samples from the females (48.29) were also significantly lighter (p= 0.0057) than the males’ (37.79). For a* value (redness), there was a significant difference (p< 0.0001) between the slaughter methods. The conventional group meat (15.58), were redder than the Kosher meat (10.40). Gender effect was also significant (p< 0.05), with meat from the males (13.81) appearing redder than the females’ (11.25). For b* value (yellowness), significant difference (p< 0.0001) was also found between the slaughter methods. The Kosher meat samples (-6.49) appeared yellower than those from conventional slaughter (0.26). FC-3 samples (-2.36) were also significantly (p= 0.0112) yellower than the FC-2 samples (-3.05). For pH, analyses revealed a significant difference (p< 0.0380) at 45 minutes post-mortem (pm) between slaughter methods. The kosher carcasses (pH= 6.43) had a slightly higher pH compared to the conventionally slaughtered carcasses (6.33). The ES carcasses (pH=6.16) also had a significantly lower (p< 0.0001) pH compared to the NES carcasses (pH=6.89). At 3hrs pm, only electrical stimulation showed a significant influence (p< 0.0001). The ES carcasses (pH= 5.72) were lower than the NES group (pH= 6.49). At 6hrs, only electrical stimulation still showed a significant influence (p< 0.0001), with the ES carcasses (5.56) still having a faster decline compared to the NES group (pH= 6.01). At 12hrs, the ES group (pH= 5.61) still had a significantly (p= 0.0008) lower pH than the NES group (pH= 5.82). At 24hrs, only the slaughter method showed a significant influence (p= 0.0314) in carcass pH, with the Kosher carcasses (pH= 5.53) having a slightly lower pH compared to the conventionally slaughtered ones (pH= 5.56). The latter difference is probably not of any practical significance and could be ignored. Temperature at 45 minutes pm showed a significant difference (p= 0.0248) between the slaughter methods with the carcasses from Kosher slaughter (36.500C) having a slightly lower temperature compared to those slaughtered conventionally (37.220C). At 3hrs pm, the carcasses from Kosher slaughter (30.060C) had a significantly higher (p= 0.0005) temperature than the conventional group (27.050C). The female carcasses (31.260C) also had significantly higher (p< 0.05) temperature compared to the male carcasses (27.890C). The FC-2 carcasses (28.190C) also had a significantly lower temperature (p= 0.0149) compared to FC-3 (30.110C) which was anticipated due to lower temperature decline in those with lower subcutaneous fat. At 6hrs pm, the conventionally slaughtered carcasses (14.710C) still showed a significantly faster decline (p< 0.0001) compared to those slaughtered by Kosher (20.16). FC-2 carcasses also showed a significantly (p= 0.0104) lower temperature (16.680C) compared to FC-3 (18.740C). At 12 hrs pm, the conventionally slaughtered carcasses (4.720C) still had a significantly (p< 0.0001) lower temperature compared to the Kosher group (10.240C). The FC-2 group (6.690C) also had a significantly (p= 0.0011) lower temperature compared to the FC-3 group (8.890C). Finally at 24 hrs after slaughter, slaughter method still showed a highly significant influence (p< 0.0001) with the conventionally slaughtered carcasses having a much lower temperature (-0.420C) compared to the Kosher group (3.060C). The male’ carcasses (0.620C) also had significantly lower (p< 0.05), ultimate temperature compared to carcasses from the females (2.990C). There was also a significant difference (p< 0.05) between the fat codes, with the FC-2 carcasses (1.010C) showing a lower temperature, compared to the FC-3 (1.710C) carcasses. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Animal and Wildlife Sciences / Unrestricted

O experimento consistiu de dezesseis tratamentos distribuídos num esquema fatorial 4x2x2, sendo 4 genótipos (Excel (E) - Nn, Linha 21 (L21) - nn, Maximus (M) - NN e Optimus (O) - NN), 2 sexos (machos castrados e fêmeas) e 2 pesos (leves – 95 a 100Kg e pesados – 115 a 120Kg) e seis repetições. Foram realizadas medidas de composição da carcaça: Peso da Carcaça Resfriada (PCR), Área de Olho de Lombo (AOL), Comprimento de Olho de Lombo (COL), Profundidade de Toucinho (PT), Porcentagem de Carne Magra (%CM) e medidas de Espessuras de Músculo (EM) e Gordura (EG) e avaliações de qualidade de carne: pH, cor (L*a*b*), Perda por Exsudação (PE) e Capacidade de Retenção de Água (CRA). Os resultados estatísticos da composição da carcaça para o genótipo nn indicaram valor de AOL significativamente superior em relação aos genótipos Nn, NNM e NNO e valor de PT significativamente menor que NNM e NNO, porém, não diferindo de Nn. Quanto à EM, ocorreu uma tendência do NNM apresentar os maiores valores, seguido pelo Nn, nn e NNO. Em relação à EG, NNO mostrou os maiores valores, não diferindo significativamente de NNM e nn, enquanto o genótipo Nn apresentou o menor valor para esta característica. A %CM dos genótipos nn e Nn foi significativamente maior que NNM e NNO, confirmando a expressão do gene recessivo (n) em depositar mais carne na carcaça que o dominante (N). Os resultados estatísticos de qualidade de carne mostraram que o genótipo nn apresentou o menor valor de pH24 no músculo Semimembranosus, combinado com os maiores valores de luminosidade (L*) e PE em comparação com Nn, NNM e NNO. Não houve diferença significativa entre os genótipos NN and Nn na PE. Em relação à CRA, NNM obteve valor significativamente menor que Nn, nn e NNO. Os resultados obtidos permitem concluir que o gene halotano em homozigose (L21) contribuiu para a obtenção de uma carcaça mais musculosa, porém, com qualidade de carne inferior, apresentando maior incidência de carne PSE. Em relação ao sexo, os machos resultaram carcaças mais pesadas, mais gordas e carne com menor luminosidade. Finalmente, com exceção da %CM, os valores de composição da carcaça aumentaram com o peso de abate, não sendo constatadas mudanças nas características de qualidade avaliadas. / This experiment consisted of sixteen treatments in a 4x2x2 factorial arrangement, 4 genotypes (Excel – Nn, Line 21 – nn, Maximus – NN and Optimus – NN), 2 sexes (barrows and gilts) and 2 weights (light – 95-100Kg and heavy – 115-120Kg) and 6 repetition. The exams were submitted to the following carcass composition measurements: Cold Carcass Weight (CCW), Loin Eye Area (LEA), Loin Eye Length (LEL), Fat Depth (FD), Lean Meat Percentage (LM%) and Fat (FT) and Muscle (MT) Thickness. Meat quality measurements were also realized: pH, Color (L*a*b*), Drip Loss (DL) and Water Holding Capacity (WHC). The results of this study showed that genotype nn had shown significantly higher values of LEA than another genotypes and significantly lower values of FD than NNM and NNO, and it didn’t differ from genotype Nn. There was a tendency by genotype NNM to show higher values of MT followed by Nn, nn and NNO. Genotype NNO showed higher values to FT and did not differed significantly from NNM and nn, while genotype Nn showed lower values to this characteristic. Genotypes nn and Nn showed significantly higher values of LM% than NNM and NNO. With reference to meat quality, genotype nn has shown lower value of pH24 measured in the muscle Semimenbranosus and higher values of L* and DL than genotypes Nn, NNM and NNO. Genotype NNM had significantly higher values of WHC than nn, Nn and NNO. There was no significant difference between NN and Nn when considered DL. The results above indicate that halothane gene in homozygous (nn) helped to obtain more muscular carcasses. On the other hand, this genotype showed worst meat quality. As a consequence of that, genotype nn has shown higher incidence of pale, soft and exudative meat. With reference to sex, barrows had significantly higher values to CCW, FD, FT, L* and b*, resulting paler meat and heavier and fatter carcass than gilts. Except for LM%, as carcass weight increased there were increases in all the characteristics. The data from this study suggest that there were no meat quality differences between the two slaughter weights.

Dez novilhos Nelores, com média de 36 meses, foram abatidos no Abatedouro-Escola da Faculdade de Zootecnia e Engenharia de Alimentos da PCAPS-USP e lados alternados de suas carcaças foram resfriados pelo sistema tradicional, tendão de Aquiles do traseiro especial (TA), ou na forma horizontal (HO). As carcaças foram resfriadas por 48 horas, entre 0-2ºC. Foi avaliada a área de olho de lombo (AOL) e espessura de gordura subcutânea (EGS). Em seguida, foram retiradas amostras dos músculos Longissimus dorsi (LD), Quadríceps femoris (QF), Supraspinatus (SU), Psoas major (PM) e Semitendinosus (ST), embaladas a vácuo, maturadas por 5 dias em câmara de resfriamento e congeladas para posterior análises. Não houve diferença entre a EGS e a AOL para o LD dos tratamentos TA e HO. As amostras foram descongeladas em câmara fria vinte e quatro horas antes das análises e a seguir a maciez foi avaliada pelo método Warner Bratzler Shear Force. Não houve diferença na maciez dos músculos SU, PM e ST, independente do tratamento. Porém, a força de cisalhamento do QF (p=0,0291) foi menor para o HO (5,13 kg) do que para o TA (6,24 kg). O mesmo foi observado para o músculo LD (p=0,0068), com valores de força de cisalhamento de 6,38 kg para HO e 7,73 kg para TA. O LD e QF de carcaças mantidas na posição horizontal foram mais macios. Outras pesquisas que avaliem o índice de fragmentação miofibrilar e o comprimento do sarcômero devem ser realizadas. / Ten Nellore steer carcasses, with average age of 36 months were slaughtered at the meats lab of FZEA – USP and alternate right or left sides were placed in the cooler hung either by the Achilles tendon (TA) or horizontally placed over pallets, outside facing up (HO). Carcass were chilled for 48 hours at 0 – 2ºC. After the chilling period, loin eye area (LEA) and fat thickness (FT) were measured. One inch thick samples from each of the following muscles were removed, loin, tenderloin, eye round, knuckle and chuck tender and after 5 days in the cooler were frozen for future analysis. There was not a statistical difference for LEA and FT between treatments. After thawing the samples were analyzed for shear force through the Warner Bratzler device and there was not statistical difference for the tenderloin, eye round and chuck tender muscles between treatments. The shear force of the knuckle (5.13 Kg) was lower (p=0.029) for the HO treatment than for the TA (6,24 Kg). The loin also had a shear force of 6,4 Kg statistically lower (p=0.007) for the HO treatment when compared to 7.7 Kg for the TA treatment. The loin and knuckle of the carcasses cooled horizontally were more tender. Further studies evaluating MFI and sarcomere length must be done.

Orientador: Reginaldo José Donatelli / Resumo: Os insetos representam atualmente mais de 60% das espécies de animais descritas, mas apesar de sua riqueza a quantidade de estudos de conservação com a classe Insecta em território nacional ainda é pequena. As ordens mais utilizadas com base em conservação são também as mais diversas da Classe principalmente por desempenharem diversas funções ecológicas, tais como em associações com substrato cadavérico, tema desse trabalho. A maioria das pesquisas envolvendo insetos necrófagos está associada à ambientes urbanos. O presente estudo teve como objetivo fazer um levantamento da fauna de insetos necrófagos presentes em uma fitofisionomia de Floresta Atlântica. O local de estudo foi a Estação Ecológica dos Caetetus, localizada entre os municípios de Gália e Alvinlândia, estado de São Paulo. A Estação guarda um dos últimos fragmentos remanescentes de Floresta Atlântica, que possui fitofisionomia de floresta estacional semidecídua, caracterizada principalmente por conter duas estações: fria e seca; e quente e chuvosa. Para fazer o levantamento dos insetos foram utilizadas armadilhas atrativas com carne suína. A abundância total registrada foi de 39.412 indivíduos distribuídos em 232 morfoespécies. Dentre estas, as espécies necrófagas compreenderam aproximadamente 24% do total amostrado, sendo a segunda guilda alimentar mais abundante; a espécie mais abundante dentre elas, foi Mesembrinella sp (Diptera), registrada apenas em ambientes não antropizados, evidenciando que o fragmento ain... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Insects currently represent over 60% of the animal species described, but despite their richness there are few conservation studies with the Insecta class. The most used orders based on conservation are also the most diverse in the Class, mainly because they perform various ecological functions, such as in associations with cadaverous substrate, the subject of this work. Most research involving necrophagous insects is associated with urban environments. This study aimed to survey the scavenger insect fauna present in an Atlantic Forest phytophysiognomy. The study site was the Caetetus Ecological Station, located between the municipalities of Gália and Alvinlândia, São Paulo. The Station houses one of the last remaining fragments of the Interior Atlantic Forest, which has a semi-deciduous forest phytophysiognomy, characterized mainly by having two seasons, one dry and one rainy. To survey the insect attractive traps with pork were used throughout the four seasons. The total abundance recorded was 39,412 individuals distributed in 232 morphospecies. Among these, the necrophagous species comprised approximately 24% of the total sampled, being the second most abundant food guild; the most abundant species was Mesembrinella sp, recorded only in non-anthropized environments, showing that the fragment still manages to maintain the predominance of a native species, although exotic species are found. / Mestre

Le système INRA d’alimentation des Ruminants prédit les réponses de l’animal à des variations d’apports d’aliments ingérés. Toutefois, il évalue mal l’influence de l’alimentation sur la qualité des productions, et en particulier la qualité de la carcasse de bovins dont dépend le paiement des animaux aux producteurs. Pour un type d’animal donné, les poids et composition de la carcasse en lipides et protéines sont prédits par le modèle MECSIC (Hoch et Agabriel, 2004) à partir de l’énergie métabolisable ingérée calculée selon le système INRA de valeur énergétique des aliments et des rations. Or une étude bibliographique suggère que la composition des dépôts dépend aussi pour partie de la composition des rations qui détermine la nature des produits terminaux issus de la digestion des rations et le devenir métabolique des nutriments. Pour tester cette hypothèse, l’objectif fut d’étudier l’effet de la nature de la ration à même quantité énergie métabolisable (EM) ingérée sur la composition des dépôts et de la carcasse. Cet objectif est ciblé sur les bovins mâles en croissance. Les étapes principales de la thèse ont consisté à i) construire une base des données à partir des publications internationales traitant des effets de la variation des rations ingérées sur la composition de la carcasse chez les jeunes bovins, ii) explorer les relations entre la composition de la carcasse et la composition de la ration et sa métabolisabilité. La constitution de la base de données a montré que la composition de la carcasse n’est mesurée que dans 20% des publications, les 80% restantes l’ayant évalué par des mesures indirectes (index USA de rendement de viande, épaisseur de gras sous cutané, persillé, surface de muscle…) qui ne sont pas reliées entre elles. Une étape de recherche préliminaire a été mise en place pour quantifier par méta-analyse les relations entre mesures directes et indirectes de la composition de la carcasse dans le but d’utiliser le maximum de publications pour la suite de la thèse. Nous avons montré que seuls deux indicateurs (index USA de rendement de viande et épaisseur de gras sous-cutané) reflètent correctement la composition de la carcasse et peuvent être utilisés pour établir les lois de variation de sa qualité selon les conditions d’alimentation. Une autre méta-analyse a permis d’explorer à niveaux d’ingestion d’EM similaires, les réponses marginales des dépôts de lipides et protéines dans la carcasse, à des variations strictes de teneurs de la ration en EE, PDI, NDF ou du rapport Amidon/NDF, tout en considérant sa métabolisabilité (q=EM/EB). L’accroissement du rapport Amidon/NDF augmente la teneur en lipides des carcasses mais en deçà d’un seuil de métabolisabilité de la ration de 0,65, i.e. si les rations ont plus de 36% de fourrages. Au-delà de ce seuil, qui correspond à un rapport Amidon/ NDF minimal voisin de 2, il n’y a plus d’effet. Ainsi à même EMI, la composition du gain (et donc l’énergie nette déposée) ne varierait pas linéairement avec la métabolisabilité q de la ration. De plus la teneur en PDI augmente significativement la proportion de lipides de la carcasse (et réduit celle des protéines), surtout si le niveau global d’apports de PDI est limité et ne dépasse pas 2,5 fois les besoins d’entretien en PDI. La teneur en EE a peu d’effets. Ces caractéristiques de ration conduisent à des profils de nutriments (rapport entre nutriments glucogéniques et cétogéniques, azote-alpha-aminé) qui sont aussi discriminants pour la composition de la carcasse. Nos résultats suggèrent qu’il faut considérer les effets de la nature de la ration dans la modélisation de la composition de la carcasse des bovins selon l’EM ingérée. Cela pourra faire l’objet d’une modification significative du modèle de croissance (MECSIC) pour améliorer son pouvoir prédictif. / The INRA feeding system for Ruminants predicts the animal's responses to changes in feed intake. However, it poorly evaluates the influence of feed intake on the quality of productions, and in particular the quality of bovine carcass, on which the payment of animals to the producers depends. For a given type of animal, the carcass weight and its composition in lipids and proteins are predicted by the MECSIC model (Hoch and Agabriel, 2004) from the intake of metabolizable energy calculated from the INRA energy system. However, a literature review suggests that the composition of the depots also partly depends on the composition of the rations, which determines the nature of the digestion end products, and the metabolic fate of the nutrients. To test this hypothesis, the objective was to study the effects of the nature of the ration at similar metabolizable energy intake (MEI) on the composition of the carcass. This study is targeted to growing male cattle. The main steps of the thesis consisted of (i) building a database based on international publications on the effects of dietary intake on carcass composition in young cattle, (ii) exploring the relationships between carcass composition and the composition and metabolisability of the ration. The database showed that the composition of the carcass was measured in only 20% of the publications; the remaining 80% evaluated it by indirect measurements (USA yield grade, fat thickness, marbling, ribeye area ...). A preliminary research step was developed to quantify by meta-analysis the relationships between direct and indirect measurements of carcass composition in order to use the maximum number of publications for the rest of the thesis. We have shown that only two indicators (USA yield grade and fat thickness) correctly reflect the composition of the carcass and can be used to establish the response equations of carcass quality to dietary conditions. Another meta-analysis explored the marginal responses of lipid and protein depots in the carcass to strict variations in the dietary concentrations of EE, PDI, NDF or of the starch / NDF ratio, while considering its metabolisability (q = EM / EB). An increase in the starch / NDF ratio increases the lipid content of the carcasses but below a metabolizability threshold of 0.65, i.e. when rations contain more than 36% fodder. Beyond this threshold, which corresponds to a minimum starch / NDF ratio close to 2, there is no longer any effect. Thus, at similar MEI, the composition of the gain (and therefore the net energy deposited) does not vary linearly with the metabolisability q of the diet. Furthermore, the PDI content significantly increases the proportion of carcass lipids (and reduces that of proteins), especially if the overall level of PDI intake is limited and does not exceed 2.5 fold the maintenance requirements in PDI. The dietary EE content has little effect. These diet characteristics result in nutrient profiles (glucogenic / ketogenic ration, alpha-amino-N) which also discriminate carcass composition. Our results suggest that the effects of the nature of the ration should be considered when modeling the carcass composition of bovine animals from MEI. This should lead to significant changes in the MECSIC growth model to improve its predictive power.

Methods used to estimate the prey consumption by large carnivores include direct continuous observation, stomach content analysis, carcass observations and scat analysis. Continual observations are widely considered the best approach to estimate large carnivore diets, with lions (Panthera leo) being no exception. Continual observation allows the recording of all prey encounters and biases inherent in the other approaches are minimised. However, continuous observations are not always feasible, and in situations where animals cannot be observed at all times, diets are often estimated from observed carcasses. This often leads to an over-estimation of large kills in the estimated diet. Alternative methods that are free of the constraints placed on continuous observations are needed to provide data of a similar quality to that obtained using these continuous observation bouts. I employed a cluster follow up technique to locate lion kills from remotely accessed Global Positioning System (GPS) data from lions in the Kruger National Park (KNP). I develop Generalized Linear Models (GLMs) that increase the probability of locating kills at GPS cluster events. By increasing the predictive ability of detecting kills I show that this technique can be used to locate kills in a more efficient manner than random searching of GPS clusters, with further advantages in that multiple groups of lions can be monitored simultaneously. By incorporating this technique into an adaptive research framework, the diet of lions (and that of other large carnivores) can be estimated. In addition, I show that the spatial association between lions at kill sites, while feeding on carcasses, provides a further increase in the predictive ability of kill site models. Lionesses were found to be considerably closer together at the start of clusters associated with kills in comparison to clusters where no kill was found. This pattern remained consistent for both small and large kills. This proximity approach could therefore be incorporated into the GLMs that are developed to predict kill sites of large social carnivores. To further reduce the bias (where small kills are often missed) inherent in carcass observations, I combined scats and carcasses collected from known times, locations and lion groups to construct a temporal kill record for each group of lions. By combining scats and carcasses I estimate that at least 50% of the small prey items, namely impala (Aepyceros melampus) and warthog (Phacochoerus africanus) were missed when GPS clusters were investigated for carcasses. Ultimately, I show that a combination of GPS cluster investigations based on models developed using GPS movement data in combination with lion proximity data, augmented with scats collected at GPS clusters, could provide estimates of large carnivore diets that begin to approach estimated diets obtained through continuous monitoring. The resulting diet, estimated from the GPS cluster approach in combination with scat collection, indicated that the dominant prey item in the region was zebra (Equus quagga) followed by wildebeest (Connochaetes taurinus), impala and buffalo (Syncerus caffer). Selection indices for the eight dominant prey items were calculated using prey availability measures obtained from the aerial census data and ground counts of groups. It has been suggested that group level selection is a better approach to calculating predator-prey interactions, and that stability in predator-prey systems is improved if group metrics of prey are used as apposed to individual measures of availability. I show that there is a considerable shift in selection indices, as well as in the order that prey is selected, when using different measures of prey availability. In selection studies, more effort needs to be paid to the assessment and definition of prey availability to ensure results accurately reflect selection patterns in the field, especially when data are used for the development of management practices. Combining buffalo predation data collected from GPS cluster investigations with buffalo mortality data collected over five years prior to the commencement of the GPS cluster investigations, allowed an investigation into patterns of lion predation on buffalo between 2000 and 2007. Buffalo of both sexes were more vulnerable to predation in habitats that gave lions an ambush advantage (i.e. increased grass height and tree density). Despite this similarity in landscape risk, different processes lead to similar fates in dangerous habitats for buffalo of both sexes. Predation pressure by lions on buffalo increased following periods of reduced rainfall; with more buffalo predated on following drier six month periods. Predation on males constituted a significant proportion of all predation and was focused predominantly into the late dry season. The resulting method of locating kills by using GPS clusters and correcting carcass data with scats collected along the movement path represents a robust technique to estimate large carnivore diets. In the concluding chapter I present avenues where future research can build on the current thesis and present a framework that can be employed when attempting to estimate large carnivore diets. / Thesis (PhD)--University of Pretoria, 2010. / Zoology and Entomology / unrestricted