Vitamin B₁₂ deficiency has been difficult to diagnose, mainly due to the vitamin's lack of biological significance in serum in which it is usually assayed. This research has investigated the marker of vitamin B₁₂/cobalt (Co) deficiency in sheep, methylmalonic acid (MMA), in comparison with serum and liver vitamin B₁₂ concentrations in farm situations where vitamin B₁₂ deficiency is expected in order to establish more accurate reference ranges for serum and liver vitamin B₁₂, and MMA. In addition, an attempt was made to ascertain the vitamin B₁₂ requirements of preruminant (PR) lambs, and to determine whether metabolic demand for vitamin B₁₂ influences tissue concentrations. Furthermore, since the vitamin is active in biological tissues in form of its coenzymes, 5’ -deoxyadenosylcobalamin and methylcobalamin, a preliminary assessment of variation in the distribution of these coenzymes in liver in different situations has been sought. The first trial was set up to find out if the addition of propionate to the PR lamb's diet stimulated the uptake and/or storage of vitamin B₁₂ in the liver as a reflection of the need to deal with the incoming propionate. Sixteen ten day old lambs (Dorset Down/Coopworth cross-bred) were housed indoors soon after birth and fed on milk replacer. For half of the lambs 7.5 % (w:w) of the milk powder was replaced by propionate. Within each group, four lambs were treated with 250 µg vitamin B₁₂ twice weekly. Supplementation with vitamin B₁₂ increased liver concentrations from ~250 to ~900 nmol/kg fresh tissue, but there was no effect of propionate. Propionate addition did, however, result in increased plasma vitamin B₁₂ concentrations in vitamin B₁₂ supplemented groups, values being 3323 and 2355 pmol/l in propionate supplemented and control groups, respectively. This suggested that diet could influence plasma vitamin B₁₂ concentrations. An attempt was made to quantify the PR lamb's ability to absorb vitamin B₁₂ from the alimentary tract by comparing the ability of intra-muscular (IM) and oral vitamin B₁₂ to raise plasma and liver vitamin B₁₂ concentrations. Twenty-seven three to four day old lambs from a farm with marginal Co status were housed indoors and fed on milk replacer. They were divided into three groups: control (n=3), IM treatment (n=12) and oral treatment (n=12). The two treatment groups were further subdivided into five sub-groups. These received, respectively, 0.2 (n=3), 0.4 (n=2), 0.8 (n=2), 1.6 (n=2) and 3.2 µg OH-cbl/d (n=3). The oral groups received tenfold the amount of the comparable IM groups, on the assumption that if oral absorption of the vitamin is about 10 % both groups would show similar increases in plasma and liver vitamin B₁₂ concentration. None of the IM groups showed any significant change in plasma or liver vitamin B₁₂. In the oral groups only the group on the highest dose of vitamin B₁₂, viz 32 µg/d, showed increases in plasma and liver concentrations. It was concluded that either absorption of vitamin B₁₂ was greater than 10 % or that the vitamin was retained better when administered orally. The amount retained in the livers of the lambs in the highest oral group was calculated to represent ~ 7.5 % of the dose. In a follow-up 24 h trial, 14 of the above lambs were divided into three groups: Control (n=3), oral (n=6) and IM (n=5) treatment. The IM group received 3.2 µg OH-cbl and the oral group tenfold the amount as single doses at 0800 h. Blood samples were taken at regular intervals throughout the 24 h period and assayed for vitamin B₁₂, Vitamin B₁₂ concentrations in the IM group rose steeply within the first hour after injection to a concentration that was calculated to reflect 100 % uptake of the vitamin. It rose more slowly over about 8 h in the oral group. From the area under the curve absorption of the oral dose was estimated to be ~ 7 %. The next experiment involved a farm where Co deficiency had been reported previously. In the first year, 50 pregnant two-tooth Half-bred ewes were divided randomly into two groups of 25. One group received a Co bullet plus 1000 µg OH-cb1 IM, the other group remained unsupplemented. In the following year the trial was repeated. Ewes from the previous year's trial (by then four-tooths) were augmented by a new cohort of pregnant two-tooths to make up numbers to 75. After lambing the lambs were divided into four groups: first by their dams' vitamin B₁₂ treatment, then half of each group received injections of vitamin B₁₂ at approximately three weekly intervals while the other half remained untreated. The trials lasted about five months, from mid-pregnancy until weaning. Pasture Co was at its lowest at lambing in both years, 0.09 and 0.10µg/g DM, respectively. In the first year, vitamin B₁₂ concentrations in the untreated ewes rose from 340 to 950 pmol/l in plasma and decreased in liver from 330 to 170 nmol/kg fresh tissue. In the Co treated group, vitamin B₁₂ concentrations in plasma rose from 500 to 1550 pmol/l and in liver from 310 to 560 nmol/kg fresh tissue. In the second year, vitamin B₁₂ concentrations in serum in the unsupplemented groups fell from 500 to 260 pmol/l around lambing before rising again to starting values at weaning, and liver vitamin B₁₂ concentrations fell from 450 at the start to 230 nmol/kg fresh tissue at the end of the trial. Serum vitamin B₁₂ concentrations in the two-tooth supplemented group rose from < 500 to > 3000 pmol/l whereas in the four-tooth supplemented group serum vitamin B₁₂ levels started at ~2800 and rose to nearly 5000 pmol/l. The supplemented four-tooths maintained higher liver vitamin B₁₂ concentrations throughout compared to the supplemented two-tooths, viz 680 compared to below 400 at the start and 900 versus 650 nmol/kg fresh tissue at weaning, respectively. MMA in the untreated groups rose to 15 and to 8 µmol/l during early lactation in the first and second years, respectively, whereas MMA in the treated groups stayed below 3 µmol/l in the first season and below 1.5 µmol/l in the second season. There was a live weight response to treatment in the ewes as the unsupplemented groups showed a significantly lower weight gain during the trials than the supplemented groups, viz 10.0 versus 13.6 kg in the first year, and 10.6 versus 13.3 kg in the four-tooths and 9.9 versus 12.1 kg in the two-tooths in the second year. There was also a significant difference in faecal egg count (FEC) in the first year. FEC in the untreated group was higher during lactation than in the treated group, viz 590 versus 170 eggs per gram wet faeces (epg), respectively. In the second year, the two-tooths had a higher FEC than the four-tooths, viz 120 versus 40 epg during the same time span, respectively. While there was a trend for treatment having an effect on FEC similar to that in the first year it was not significant. Supplementation of ewes in the first year increased mean milk vitamin B₁₂ concentrations at lambing from 800 to 1400 pmol/l and at weaning from 1750 to 4000 pmol/l. In the second year, Co bullet treatment increased milk vitamin B₁₂ concentrations in the four-tooths and two-tooths from 1500 and 2300 to 4000 and 2900 pmol/l at lambing, and from 1800 and 1400 to 6200 and 4500 pmol/l at weaning, respectively. Treatment of ewes increased vitamin B₁₂ concentrations in the lambs which were not themselves supplemented. Plasma values in the first year increased from 160 to 325 pmol/l soon after birth and from 650 to 900 pmol/l at weaning, and liver values from 75 to 140 nmol/kg fresh tissue soon after birth and from 150 to 240 nmol/kg fresh tissue at weaning. In the second year, plasma vitamin B₁₂ concentrations increased from 160 to 380 pmol/l soon after birth and from 500 to 700 pmol/l at weaning, and in liver from 130 to 260 nmol/kg fresh tissue soon after birth and from 220 to 340 nmol/kg fresh tissue at weaning. There was also a significant effect of ewe supplementation on lamb MMA in 1997/1998 when values decreased from 19 to 8 µmol/l around the time of rumen development. MMA in the second year stayed below 3 µmol/l throughout in all groups of lambs. There was no difference in LWG between any groups of lambs. FEC was lowest in the group where both ewes and lambs were supplemented and highest in the group where neither ewes nor lambs were treated. Further investigations were conducted on farms in Southland with lambs post-weaning in order to compare changes in serum and liver vitamin B₁₂ with serum MMA and LWG to determine the critical time and level of deficiency. In the first year, three farms with 50 lambs each participated. Lambs from each farm were allocated to five groups of 10 animals each. The first group received a Co bullet at weaning, and each month another group was treated with a Co bullet. The lambs were weighed monthly, and blood and liver samples were taken prior to treatment and each subsequent month from five lambs of the first supplemented group. The trial lasted about four months. Serum vitamin B₁₂ concentrations in lambs at weaning were between 500 and 1000 pmol/l. Although supplementation increased serum levels for the first month this was followed by a drop to near or below starting concentrations. An exception was Farm 3 where serum vitamin B₁₂ concentrations rose again at the end of the trial. Liver vitamin B₁₂ concentrations also showed an overall decline from starting levels (200 to 300 nmol/kg fresh tissue) to the end of the trial (100 to 200 nmol/kg fresh tissue). MMA started around 2 µmol/l and reached between 6 and 7 µmol/l in the untreated lambs on Farms 1 and 3 two months after weaning before decreasing to around 3 µmol/l at the end of the trial, whereas the treated lambs maintained MMA concentrations around 2 µmol/l. On Farm 2 MMA started just below 5 µmol/l, decreased to around 1 µmol/l for treated and untreated lambs one month later and rose again to between 2.5 and 4 µmol/l, respectively, at the end of the trial. LWG was below average for all lambs (between 0.20 and 0.04 kg/d except for Farm I in the first month after weaning) but no significant differences were noted between treated and untreated lambs on any of the farms. Another trial was conducted on one of these farms in the following year. One hundred lambs were divided into two groups of 50 each at weaning and sampled monthly for about six months. One group was treated with two Co bullets, the other group remained untreated. Pasture Co was between 0.04 and 0.07 µg/g DM, yet serum levels for the untreated group stayed ~500 pmol/l throughout the trial. Serum vitamin B₁₂ concentrations for the treated group started at ~500 pmol/l, rose to ~2500 pmol/l before falling back to ~2000 pmol/l. Liver vitamin B₁₂ concentrations for the untreated and treated groups were 529 and 427 nmol/kg fresh tissue at weaning, respectively. This decreased for both groups to ~350 nmol/kg fresh tissue one month after weaning. In the untreated lambs liver values decreased further to ~290 nmol/kg fresh tissue whereas they increased to ~450 nmol/kg fresh tissue for the treated group at the end of the trial. MMA concentrations started between 2 and 3 µmol/l for both groups and increased to 4.5 µmol/l for the untreated group one month later before falling back to 3.2 µmol/l. In the treated group MMA decreased to ~1µmol/l and stayed at that level throughout the trial. There was no difference in weight gain. In order to obtain an understanding of the distribution of corrinoids in biological tissues a High Performance Liquid Chromatography method was developed. The sensitivity of the analytical method meant that it was only practical to assay mainly liver samples because of the higher vitamin B₁₂ concentrations than in other tissues. The general finding was that the coenzyme 5’ –deoxyadenosylcobalamin (ado-cbl) constituted the highest proportion of corrinoids in liver (45 %), followed by analogues (28 %), OH-cbl (24 %) and lastly methy1cobalamin (3 %). Ado-cbl did tend to be proportionately higher in supplemented than in unsupplemented animals (56 and 42 %, respectively), whereas biologically non-active analogues tended to be higher in untreated than in treated sheep (29 and 21 %, respectively). It was concluded that in the farm trials Co deficiency was only mild or not present although deficiency would have been predicted from the low vitamin B₁₂ concentrations in serum and liver and from raised MMA values. Therefore, currently used thresholds in New Zealand appear to be too high for vitamin B₁₂, and overseas values for MMA do not seem to be appropriate. Revised marginal ranges of 100 to 200 pmol/l for serum, 100 to 200 nmol/kg fresh tissue for liver and 10 to 20 µmol/l for MMA are suggested. Further, this work shows that Co bullets were effective in elevating blood and liver vitamin B₁₂concentrations for longer than one year. In the trials with preruminant lambs it was found that maintenance requirements were met by the vitamin B₁₂ content of milk replacer. There is evidence from indoor and farm trials that vitamin B₁₂ from milk was much more readily absorbed than vitamin B₁₂ from supplements. It was estimated that suckling lambs probably require between 1200 and 4000 pmol vitamin B₁₂/d, depending on age.

Five rotational grazing experiments were carried out at Massey University's Riverside farm, in the Wairarapa, on the East Coast of the Southern North Island, New Zealand, to compare the effects of feeding Lotus corniculatus L. (birdsfoot trefoil; cv. Grasslands Goldie) or perennial ryegrass (Lolium perenne)/white clover (Trifolium repens) dominant pasture upon sheep year round productivity. These studies also investigated under grazing, seasonal and annual net herbage accumulation rate and seasonal dynamics of undisturbed (i.e. non-grazed) net herbage accumulation rate of L. corniculatus relative to that of grass-dominant pasture. Aspects of in vivo digestibility of dry matter (DMD), organic matter (OMD), digestible organic matter in the dry matter (DOMD) and metabolisable energy (ME) concentration of L. corniculatus at different stages of maturity over the spring, summer and autumn were investigated in three indoor digestion trials. 1. Two field experiments (Chapter 2) were conducted during spring to assess the effects of grazing mixed age undrenched ewes on L. corniculatus (n = 50) or pasture (n = 50) and their lambs (mainly twins) on live weight (LW), wool production, faecal nematode egg count (FEC) and dag score. In Experiment 1 (18 October 2000 to 21 January 2001) and Experiment 2 (3 October 2001 to 2 January 2002) both forages were fed ad libitum. Total condensed tannin (CT) concentration in the diet selected was 24 to 27 g CT/kg DM for L. corniculatus and 1.4 to 1.5 g CT/kg DM for pasture. The LW gain, weaning LW and wool production were consistently greater (P < 0.001) for lambs grazing L. corniculatus, in either Experiment 1 (258 vs. 189 g/day; 36.1 vs. 30.1kg; 1.17 vs. 0.98 kg) and in Experiment 2 (247 vs. 162 g/day; 31.8 vs. 24.1kg; 1.17 vs. 0.81 kg), respectively. Ewe and lamb dag scores were strongly and positively correlated with dag weight (P < 0.001) and generally increased with time in sheep grazing pasture, whilst grazing on L. corniculatus consistently reduced dag score. FEC in ewes grazing pasture showed a post-parturient rise (PPR) following lambing, whilst ewes grazing L. corniculatus had a reduced PPR in FEC. Up to day 70, FEC in lambs grazing L. corniculatus was lower than that for lambs grazing pasture, but between day 70 and the end of both experiments (approximately day 90), FEC in lambs grazing L. corniculatus increased to similar values as for pasture-fed lambs. FEC was not correlated with dag score or dag weight in ewes or lambs grazing pasture, but these indices were weakly and positively correlated in ewes and lambs grazing L. corniculatus, suggesting that lowering FEC on L. corniculatus also reduced dag formation. It was concluded that under dryland farming conditions, the use of L. corniculatus during the spring/early summer lactation period can increase lamb LW and wool production, whilst eliminating the need for pre-lambing anthelmintic drenching and probably reducing the amount of insecticide needed to control flystrike. These effects compared to pasture are probably due to higher digestibilty, higher ME concentration, higher voluntary feed intake (VFI), and to the effect of CT in reducing rumen protein degradability and controlling internal parasites in sheep grazing L. corniculatus. The absence of endophyte in L. corniculatus may have also have contributed to these effects. 2. During 2001 and 2002 (Chapter 3), grazing trials from February to November were conducted for 279 days (Experiments 1) and 285 days (Experiment 2), to compare the effects of grazing shorn mixed age Romney ewes in light condition on L. corniculatus versus pasture during the mating period (9 weeks, Experiment 1) and 11 weeks (Experiment 2). In Experiment 2, the length of time (days) that ewes need to graze L. corniculatus before mating to maximise reproductive performance was also investigated. Common objectives in both Experiments were to measure forage feeding effects on ewe wool production and LW of their lambs at weaning. In Experiment 1, groups of ewes (n = 100) were fed on either L. corniculatus or pasture at a herbage allowance of 1.8 kg green DM/ewe/day for the first three weeks of feeding and increased to ad libitum (2.3 kg green DM/ewe/day) during the mating period for two cycles. In Experiment 2, groups of 75 ewes grazed L. corniculatus for 42, 21, 10 and 0 days before a synchronised oestrus, with pasture being grazed for the balance of the 42 days. All L. corniculatus groups continued grazing L. corniculatus for a further 5 weeks. Feed allowance was initially 2.0 kg green DM/ewe/day, increased to 2.3 kg green DM/ewe/day during the mating period over the two cycles. At the end of L. corniculatus feeding in both experiments the groups were combined and grazed on pasture until weaning. Total CT concentration in the diet selected was 18 to 29 g CT/kg DM for L. corniculatus, with only trace amounts in pasture. In Experiment 1 mating ewes on L. corniculatus compared to pasture increased number of lambs born and lambs weaned per ewe lambing by 16 and 32% units respectively (P < 0.05), due to more multiple and less single births (P = 0.06) and to reduced lamb mortality (P < 0.05) between birth and weaning. In Experiment 2, increasing the numbers of days of grazing L. corniculatus before ovulation (0, 10, 21, 42 days) linearly increased ovulation rate (P < 0.05), lambs born and lamb weaned by up to 16% units, but had no effect upon lamb mortality. Mating ewes on L. corniculatus increased wool production (P < 0.01) and fibre length (P < 0.05) in Experiment 1 but not in Experiment 2. Grazing L. corniculatus had no effect on lamb birth weight and only small positive effects on weaning LW. It was concluded that, under commercial dryland farming conditions, the use of L. corniculatus during the mating season in late summer/autumn can be used to increase reproductive efficiency and wool production, with the largest responses in years with exceptionally dry autumn periods. These effects are probably due to the higher digestibility and ME concentration of L. corniculatus than pasture and to the CT in L. corniculatus reducing rumen protein degradability and leading to greater essential amino acid (EAA) absorption from the small intestine. Effects of forage CT upon the uterine microenvironment at the time of conception, implantation and early foetal growth, need to be investigated in future studies. It is also suggested that effects of mating on L. corniculatus upon lamb mortality between birth and weaning should be further investigated with ewe numbers/treatment increased from 100 to 350. 3. During the summer of 2002/2003, another grazing trial (Chapter 4: 95 days) compared the effects of grazing L. corniculatus and pasture on LW and the dynamics of nematode parasite infection in Suffolk x Romney weaned lambs fed ad libitum. Half of the lambs (n = 30) grazing either L. corniculatus or pasture received oral anthelmintic at the start and at monthly intervals (regular-drenched groups), whilst the remaining 30 lambs in each treatment only received oral anthelmintic when mean faecal nematode egg counts (FECs) exceed 1,000 eggs/g wet faeces (trigger-drenched groups), which occurred on day 58 only for both groups. Trigger and regular-drench lambs grazed separate areas. Total CT concentration in the diet selected was 40 to 31 g CT/kg DM for L. corniculatus, with only trace amounts in pasture. Regular-drenched lambs grazing L. corniculatus had significantly higher LW gain (298 g/day) and carcass weight gain (133 g/day) than all the other groups, whilst trigger-drenched lambs grazing L. corniculatus had significantly greater LW gain (228 g/day) and carcass gain (99 g/day) than regular-drenched (200; 66 g/day) and trigger-drenched (187; 63 g/day) lambs grazing pasture. Carcass fatness was significantly lower for trigger-drenched lambs than for regular-drenched lambs, when fed either L. corniculatus or pasture. Dag score was consistently lower for regular-drenched lambs grazing L. corniculatus than pasture; trigger-drenched lambs showed similar effects up to day 48, with no differences between the two groups thereafter. Regular anthelmintic treatment maintained FECs at low values, while parasitised lambs on L. corniculatus tended to have higher FECs than pasture-fed lambs. Relative to trigger-drenched lambs that grazed pasture, grazing trigger-drenched lambs on L. corniculatus had significantly reduced worm burdens of Haemochus contortus, Teladosargia spp., Nematodirus spp. and Cooperia spp. at slaughter, but greater burdens of Trichostrongylus spp., Chabertia ovina, Oesophagostonum spp. and Trichuris ovis were present in L. corniculatus-fed lambs. It was concluded that grazing L. corniculatus under dryland farming conditions compared to pasture can increase LW gain of weaned lambs, whilst reducing reliance on anthelmintic drenches to control parasites. These effects are probably due to increased protein supply from the action of CT enabling the lambs to have a higher LW gain when carrying a parasite burden, and to L. corniculatus better maintaining its high ME value under drought conditions. Using L. corniculatus to finish weaned lambs without anthelmintic drenches for a seven-week period is proposed. 4. A three-year study (Chapter 5; November 2000 to October 2003) was conducted to compare, under grazing conditions, seasonal and annual grazed net herbage accumulation rate and seasonal dynamics of undisturbed (i.e. non-grazed) net herbage accumulation rate of L. corniculatus relative to grass-dominant pasture. Prediction equations to estimate standing DM in L. corniculatus and pasture from the rising plate meter (RPM) and sward surface height were also generated. L. corniculatus and pasture growing in a moderate fertility and low-pH soil (pH 5.35) accumulated similar total herbage masses (24.3 vs. 24.1 t DM/ha) over the 3-year period, with the DM production being greater for L. corniculatus than for pasture during 2000-2001, producing more DM during summer/autumn drought conditions. The net herbage accumulation rate from undisturbed areas of L. corniculatus and pasture were similar in spring, summer and autumn. Seasonal variation in the calibration regressions fitted to estimate herbage mass of L. corniculatus non-destructively, suggested a combination of destructive and nondestructive methods are needed to assess herbage mass. It was concluded that L. corniculatus has the potential to increase the performance of a pasture-based sheep dryland farming system due to its ability to grow in acidic soils, its tolerance of drought conditions during summer/autumn and its seasonality of feed supply. 5. Three digestion experiments involving cryptorchid weaned lambs were conducted for 14 days over the spring, summer and autumn to determine changes in in vivo digestibility of DM, OM, digestible OM in the DM and ME concentration of L. corniculatus at different stages of maturity. In vivo digestibility samples were then used as standards to investigate if the enzymatic in vitro system of Roughan and Holland (1977) could predict OMD and DOMD of CT-containing L. corniculatus. Digestibility of L. corniculatus declined as it matured, but the rate of decline was much less than occurs for temperate grasses and for white clover. It was concluded that the in vitro enzymatic system of Roughan and Holland (1977) can be used to predict OMD and DOMD of L. corniculatus, provided a standard curve involving in vivo data generated with L. corniculatus is used. Using a standard curve with in vivo data from pasture led to bias which increased at lower OMD values. Reasons for the consistent differences between L. corniculatus and pasture standard curves are discussed, including possible effects of residual bound CT in lowering in vitro digestibility. From this series of experiments, this study is the first to report that relative to conventional perennial ryegrass/white clover, mating ewes on L. corniculatus under grazing conditions may reduce post-natal lamb mortality. It is also the first study to show that grazing sheep on L. corniculatus can maintain productivity during spring and summer with reduced dependence on anthelmintic drench input. It is concluded that whole farm modelling, mechanical harvesting and conservation strategies, selection of L. corniculatus germplasm for creeping-type plants more suited to grazing and the integration of new crops containing secondary compounds, such as chicory, should be considered to support major advances in sustainable dryland sheep farming systems.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 4 uppsatser.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Growth dynamics of Italian ryegrass (Lolium multiflorum Lam) under different grazing intensities were studied, using marked tillers. The experimental design was completely randomized, with four repetitions (transects) and three treatments consisting of grazing intensities: High , Mean and Low , corresponding to the disappearance of 61.0, 43.3 and 21.1% of the initial forage mass value, respectively. The experimental animals were ewe lambs; rotational grazing was used and the thermal sum of 313 degree-days determined the interval among grazing periods. Grazing intensities affected the morphogenesis and structure of Italian ryegrass only in the period from 24/07 to 02/09. During this period, the Italian ryegrass in the Mean grazing intensity had the lowest leaf appearance rate and leaf elongation rate and it had the highest values of leaf life span. The pseudostem height, the length of the intact and defoliated blades, the number of intact and senescent leaves were higher in Low intensity, and did not differ between Mean and High . In Low intensity, the highest growth and senescence flows were registered, respectively, 85.6 and 54.6 kg/ha day of dry matter (DM). In Mean and High intensities, the growth and intake flows were higher in the beginning of pasture utilization and the senescence flow increased during the Italian ryegrass growing season. The choice of the grazing intensity should be based on the aim of management: when the intention is to prioritize individual weight gain, it is recommended the adoption of the intensity of 43.3%, which allows greater intake of blade s leaf by lambs; but when the objective is to prioritize production per area, it is recommended to use the grazing intensity of 61.0%, because under this intensity Italian ryegrass allows higher stocking rate values. / Estudou-se a dinâmica de crescimento de azevém (Lolium multiflorum Lam.) sob diferentes intensidades de pastejo, por meio de perfilhos marcados. O delineamento experimental foi inteiramente casualizado, com quatro repetições (transectas) e três tratamentos constituídos por intensidades de pastejo: Alta , Média , Baixa , correspondentes ao desaparecimento de 61,0; 43,3 e 21,1% do valor da massa de forragem inicial, respectivamente. Os animais experimentais foram cordeiras, o pastejo foi rotativo e a soma térmica de 313 graus-dia constituiu o intervalo entre pastejos. As intensidades de pastejo afetaram a morfogênese e estrutura de azevém apenas no período de 24/07 a 02/09. Nesse período, o azevém, na intensidade de pastejo Média , apresentou as menores taxas de aparecimento e elongação foliar e os maiores valores de duração de vida das folhas. A altura do pseudocolmo, o comprimento de lâminas intactas e desfolhadas, o número de folhas intactas e em senescência foram superiores na intensidade Baixa , sem diferir entre Média e Alta . Na intensidade Baixa observaram-se os maiores fluxos de crescimento e senescência, respectivamente 85,6 e 54,6 kg/ha/dia de matéria seca (MS). Nas intensidades Média e Alta , os fluxos de crescimento e consumo foram superiores no início da utilização da pastagem, enquanto o fluxo de senescência aumentou ao longo da estação de crescimento do azevém. A escolha da intensidade de pastejo deve ser baseada no objetivo do manejo: quando se objetiva priorizar o ganho de peso individual, recomenda-se a adoção da intensidade de 43,3%, que permite maiores consumos de lâminas foliares por cordeira; já quando se objetiva priorizar a produção por área, recomenda-se a utilização da intensidade de pastejo de 61,0%, pois sob essa intensidade o azevém permite maiores valores de taxa de lotação.

Les ovins D’man sont élevés dans les oasis tunisiennes selon un rythme accéléré permettant d’avoir trois agnelages en deux ans. En plus des effets directs du mode d’élevage et d’environnement exercés sur les brebis D’man, la prolificité élevée pose question quant à la survie, la croissance et le bien-être des agneaux. L’objectif de ce travail est de déterminer les facteurs de risque qui affectent la survie et la croissance chez les agneaux D’man élevés dans les oasis de Gabès. Dans une première étape, le travail a traité les facteurs de risque d’ordre zootechnique et environnemental sur la base des données concernant 1189 agneaux élevés à la ferme de l’OEP de Gabès. En moyenne, un taux de mortalité égal à 13,4% a été observé de la naissance au sevrage dont 41% pendant les 10 premiers jours de vie, 29% entre 10 et 30 jours et 30% entre 30 et 70 jours. Le taux de mortalité est plus élevé chez les agneaux nés en hiver (23,5%) par comparaison au printemps (12,3%), l’automne (10,2%) et l’été (9,5%). A cause de leur poids léger, les agneaux issus des portées multiples (triples et quadruples) ont un taux de mortalité plus élevé (52,2%) comparés à ceux issus des portées simples et doubles ayant un poids de naissance medium (24,4%) ou lourd (1,8%). Les agneaux nés en printemps sont plus lourds à la naissance, à 30 et 70 jours et par conséquent ont des vitesses de croissance plus importantes par comparaison aux agneaux nés en hiver, en automne et en été. Le poids à la naissance et les vitesses de croissance sont également influencés par la taille de portée et l’âge de la brebis. Le faible poids à la naissance (≤ 1,5 kg), les portées multiples (quadruples et quintuples) et les agnelages d’hiver sont les principaux facteurs de risque pour la survie et la croissance des agneaux D’man. / D’man ewes are reared in Tunisian oases under an accelerated management system allowing breeders to have three lambing periods every two years. High prolificacy may accentuate the detrimental effects of an accelerated lambing system through problems which affect growth, welfare and survival. Therefore, the aim of the present study was to determine the risk factors of lamb mortality in this prolific breed maintained under intensive management in Tunisian oases. In a first step, growth and mortality rates are reported using records of 1189 lambs collected between 2004 and 2009 from an accelerated lambing system to determine risk factors according to characteristics of the animals and the environment. Results showed that overall mortality from birth to 70 days of age was 13.4%. Of all the total losses, 41% of the lambs died within 10 days of birth, 29% died between 10 and 30 days of age and 30% between 30 and 70 days. Mortality rate was significantly higher in winter (23.5%) than in spring (12.3%), autumn (10.2%) and summer (9.5%). Lambs in the low-weight category died more frequently (52.2%) than lambs from medium-weight (24.4%) to high-weight (1.8%) categories. Lambs born in spring were consistently the heaviest at birth, at 30 and 70 days of age with the greatest average daily gains compared to those born in winter, autumn and summer. Birth weights were affected by litter size and ewe age, and lambs from older ewes (2-10 years) grew faster than lambs born from young ewes (1 year). The principal risk factors identified were season (winter), birth type (multiple) and weight class (≤ 1.5 kg).

The theoretical part is concerned with the functional application of selenium and iodine supplementation methods, risks disproportionate to their income, including changes in biochemical and hematological parameters and evaluation methods of adequate saturation. The practical part analyzes the results of experiments on sheep with a defined content of selenium and iodine in the ration evaluation of selected indicators of the metabolic profile of ewes and their lambs. The results are processed statistically. It reflected the dynamics and interactions of monitored parameters.

PEREIRA, Mônica Synthia Cirino. Características da carcaça e da carne de cordeiros Santa Inês alimentados com farelo de mamona destoxificado. 2011. 110 f. : Dissertação (mestrado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Zootecnia, Fortaleza-CE, 2011 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-08-09T13:51:44Z No. of bitstreams: 1 2011_dis_mscpereira.pdf: 916233 bytes, checksum: 308779bc576dd4e96fc2c8ed32fd1977 (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-08-09T13:51:57Z (GMT) No. of bitstreams: 1 2011_dis_mscpereira.pdf: 916233 bytes, checksum: 308779bc576dd4e96fc2c8ed32fd1977 (MD5) / Made available in DSpace on 2016-08-09T13:51:57Z (GMT). No. of bitstreams: 1 2011_dis_mscpereira.pdf: 916233 bytes, checksum: 308779bc576dd4e96fc2c8ed32fd1977 (MD5) Previous issue date: 2011 / The objective of this study was to determine the characteristics of carcass and meat of Santa Inês lambs submitted to four experimental treatments with increasing concentrations of detoxified castor meal (0%, 33%, 66% and 100%) with dry matter basis. The bulk used consisted of mixed silage of elephant grass, sorghum and sugar cane. Thirty-two non-castrated male lambs were used and slaughtered with average body weight of 30 kg. Experimental tests were conducted in a completely randomized design with four treatments and eight replications (lambs). Data were submitted ANOVA and means compared by Tukey test at 5%. The animals were fasted of food and water for 24 hours and bleeding was performed with section of carotid artery and jugular vein, followed by evisceration. After slaughter, the carcasses were chilled for 24 hours at 4°C and pH was measured on the semimembranosus muscle at 45 minutes and 24 hours after slaughter, also determining weight, hot and cold carcass yield and morphometric measurements. The carcass was longitudinally sectioned into half carcasses, and retail cuts such as leg, loin, rib, rear, neck and shoulder on the right half carcass were obtained, followed by weighing and freezing of shoulder and leg for further evaluation of tissue composition. The longissimus dorsi muscle was used for the qualitative assessments of meat, weight loss due to cooking, shear force, fat content, fatty acid profile, protein content, ash, moisture and sensory analysis. Diet with 100% of castor meal showed the lowest cold carcass yield, leg circumference and chest depth. No statistical difference between treatments was observed for weight and cut yields; however, the diet influenced the rib yield, which showed the lowest value for treatment with 66% of castor meal. Carcass muscularity was affected by the diet, and in the muscle: bone ratio of the leg, a lower average for those fed with 100% of castor meal was observed. There were differences between tissue constituents of leg, muscle, bone and other tissues, and in the palette, bone and other tissues differed. The rib eye area was similar between treatments. There was a significant effect (p <0.05) between treatments for the centesimal composition, with lower percentage of fat, protein and moisture at substitution levels of 66, 100 and 33% respectively. The substitution of castor meal provided an interesting fatty acids profile for consumer health, featuring the best ratios for the evaluated relations between fatty acids. There was no statistical difference between treatments for parameters pH and shear force; however, there was an effect of the substitution in weight loss due to cooking, showing lower percentage 24.42% (p <0.05) in 33% of substitution. The sensory characteristics were evaluated considering attributes such as hardness, juiciness, flavor, color, aroma and overall acceptability. It was shown that diet with 33% of substitution provided meat with higher hardness but without compromising its acceptance. There was no change in the other meat sensory attributes. It could be concluded that the use of diets containing detoxified castor meal as partial substitution for soybean meal does not affect the carcass characteristics of Santa Inês lambs, weight and yield of retail cuts and tissue composition, maintaining its physicochemical and sensory quality. / Objetivou-se determinar as características de carcaças e da carne de cordeiros Santa Inês em confinamento, submetidos a quatro tratamentos experimentais com uso crescente de farelo de mamona destoxificado (0%, 33%, 66% e 100%) com base na matéria seca. O volumoso utilizado foi silagem mista de capim elefante, sorgo e cana-de-açúcar. Foram utilizados 32 cordeiros machos não castrados, abatidos com peso corporal médio de 30 Kg. Os ensaios experimentais foram realizados num delineamento inteiramente casualizado com quatro tratamentos e oito repetições (ovinos). Os dados foram submetidos ANOVA e as médias comparadas pelo teste de Tukey a 5%. Os animais foram submetidos a jejum hídrico e alimentar de 24 horas, a sangria foi feita com secção da artéria carótida e veia jugular, seguida da evisceração. Após o abate as carcaças foram resfriadas por 24 horas a 4º C e realizadas as leituras de pH no músculo semimembranosus aos 45 minutos e 24 horas pós abate, e determinados o peso, rendimento da carcaça quente e fria e efetuado as medições morfométricas. A carcaça foi seccionada longitudinalmente em meias carcaças, sendo obtidos os cortes comerciais de perna, lombo, costilhar, serrote, pescoço e paleta na meia carcaça direita, seguidos de pesagem e congelamento da paleta e da perna para posterior avaliação da composição tecidual. Utilizou-se o músculo longissimus dorsi para as avaliações qualitativas da carne, perda de peso por cocção, força de cisalhamento, teor de lipídios, perfil de ácidos graxos, teor de proteínas, cinzas e umidade além da análise sensorial. A dieta com 100% de farelo de mamona apresentou menor valor em rendimento de carcaça fria, perímetro de perna e profundidade de tórax. Não foi observada diferença estatística entre os tratamentos testados, para o peso e rendimento dos cortes, no entanto a dieta influenciou o rendimento do costilhar que apresentou menor valor para o tratamento com 66% de substituição de farelo de mamona. A estimativa de musculosidade da carcaça sofreu efeito da dieta, na relação músculo:osso da perna, verificou-se menor média para aqueles alimentados com 100% de farelo de mamona. Houve diferença entre os tecidos constituintes da perna, tecido muscular, ósseo e outros tecidos, na paleta diferiram os tecidos ósseos e outros tecidos. A área de olho de lombo foi similar entre os tratamentos. Verificou-se efeito significativo (p<0,05) entre os tratamentos para a composição centesimal, com menor percentual de gordura, proteína e umidade nos níveis de substituição 66, 100 e 33%, respectivamente. A substituição do farelo de mamona proporcionou um perfil de ácidos graxos interessantes à saúde do consumidor, apresentando os melhores índices para as relações avaliadas entre os ácidos graxos. Não foi observada diferença estatística entre os tratamentos para os parâmetros pH e força de cisalhamento no entanto verificou-se efeito dos níveis de substituição na perda de peso por cocção apresentando menor percentual 24,42% (p<0,05) em 33% de substituição. Avaliaram-se as características sensoriais considerando os atributos dureza, suculência, sabor, cor, aroma e aceitação global. Foi evidenciado que a dieta com 33% de substituição proporciona uma carne com maior dureza, sem, contudo, comprometer a sua aceitação. Não se observou variação dos demais atributos sensoriais da carne. Pode-se concluir que a utilização de dietas contendo farelo de mamona destoxificado em substituição parcial ao farelo de soja não interfere nas características de carcaça de ovinos Santa Inês, bem como nos pesos e rendimentos dos cortes comerciais e composição tecidual, mantendo a qualidade físico-química e sensorial.

The aim of my work was to monitor and valorize of postnatal dynamics of thyroid hormones, thyroxine (TT4), triiodothyronine (TT3) and its free fractions (FT3 and FT4), in lambs up to 60 days of age. During the experiment 26 lambs were devided into two groups according to sex and were supplemented by iodine in concentration 0,7 ? 5 mg. Standard directed day ration for sheep is average 0,3 mg of iodine in 1 kilogram of dry mass (DM). One of the groups was also supplemented by selenium in concentration 0,2 ? 0,4 mg in 1 kilogram of DM.

Made available in DSpace on 2016-12-08T16:24:07Z (GMT). No. of bitstreams: 1 PGCV06MA055.pdf: 446840 bytes, checksum: d29d16e3496cd8a5392464b7e5ac68ef (MD5) Previous issue date: 2006-11-01 / This study centered on the effects of the age at the 120, 180 and 240 days, concerning the feeding behavior and the ponderal performance of twenty-one lambs from the Crioula Wool Serrana breed. The experiment was held in a farm located at Ponte Alta, SC. The lambs were weaned with 60 days of age and kept in 5-hectare enclosures, fed with native grass and missionary grass (Axonopus sfissifolius) in association with rye-grass cultivated (Lollium perene L.) and red clover (Trifolium pretense L.) with water and mineral salt ad libitum. At night the lambs were kept in the pasture and did not have any additional food. The animals were vermifugated and vaccinated against enterotoxemy. Samples of 10 ml from the jugular vein were collected, with the addition of 3 ml Etileno-diamino-tetraceticodissodic anti-coagulant of 10%, by employing 0,1 ml in each 5ml of blood for the hematologic exams, while the other 7 ml remaining were left to coagulate and its serum used for the biochemical analises.1 ml of blood was collected from the Marginal artery ear for the settlement of the hemogasometric values. The behavioral data were obtained through visual observation, in the field, at each five minutes, during three daily consecutive periods of ten hours, in experimental age strips, corresponding to the months of december 2004, february and april 2005. Two weighings were made at each 14-day period, making a total of 1 weighings in all. The data were analyzed with delineation entirely casualized in factorial structure for sex and age. There was no effect (P<0,05) of interaction between age and sex or of te sex factor for the analyzed variables / Foram estudados os efeitos de idades aos 120, 180 e 240 dias, sobre o comportamento alimentar e o desempenho ponderal de 21 cordeiros, sendo 11 fêmeas, da raça Crioula Lanada Serrana. O experimento foi realizado num estabelecimento pecuário no município de Ponte Alta, SC. Os cordeiros foram desmamados aos 60 dias e mantidos em piquetes de cinco hectares, em pastagem naturalizada de grama missioneira (Axonopus sp) associado à pastagem cultivada de azevém (Lollium perene L.) e trevo vermelho (Trifolium pratense L.) com água e sal mineral ad libitum. Os animais foram vermifugados e vacinados contra enterotoxemia. Foram colhidas amostras de 10 mL de sangue venoso da veia jugular, desta forma uma sub-amostras de 3 mL foram adicionado anticoagulante Etileno-diamino-tetracéticodissódico EDTA, na concentração de 10%, utilizando-se 0,1mL em cada 5mL de sangue para os exames hematológicos e sub-amostras de 7 mL foram deixados para que coagulassem sendo o soro utilizado para as dosagens bioquímicas. Da artéria marginal da orelha coletou-se 1 mL de sangue para determinação hemogasométrico. Os dados comportamentais foram obtidos por observação visual, a campo, a cada cinco minutos, por três períodos diários consecutivos de doze horas, nas faixas etárias experimentais, correspondendo aos meses de dezembro de 2004, fevereiro e abril de 2005. Efetuaram-se pesagens a cada quatorze dias, totalizando quinze pesagens.apresentando os machos Os dados foram analisados em delineamento inteiramente casualizado em estrutura fatorial para sexo e idade. Não houve efeito (P>0,05) de interação entre idade e sexo e do fator sexo para as variáveis analisadas

Made available in DSpace on 2016-12-08T16:24:21Z (GMT). No. of bitstreams: 1 PGCV05MA012.pdf: 393991 bytes, checksum: 8755a862d62c91605bfe0f6eb41d8e56 (MD5) Previous issue date: 2005-08-09 / The effects of the age on the 120th, 180th and 240th days, concerning the nourishing behavior and the ponderal performance of thirteen Texel lambs were studied.The research was conducted in the Sector of Sheep Raising of CAV/UDESC, Lages, SC. The lambs were weaned with 60 days of age and fed during the day, with water and mineral salt ad libitum, in enclosures of 0,8ha, with red clover manured pasture (Trifolium pratense L.) and white clover (Trifolium repens L.) and at night they were sheltered in collective stalls and supplemented with alfalfa hay (Medicago sativa L.). The animals were wormed and vaccinated against enteroxotemy. Samples of veiny blood of 10mL were collected from the jugular vein, and in 3mL anti-coagulant Ethylenediaminotetraceticodissodic was added, in 10% concentration, by means of 0,1mL in each 5mL blood for the hematologic survey, while the remaining 7mL were coagulated, and its serum was used for the biochemical dosing. From the ear 1mL of artery blood was collected in order to establish the hemogasometric values. The average hematologic values which were gotten for the studied ages were, respectively, hematocrit or globular volume (VG) 32,50; 33,06 and 35,80%; the average corpuscular hemoglobinic concentration (CHCM) was 36,73; 37,02 and 38,09g/dL; erythrocyte 9,86x106; 10,69 x106 and 9,04 x106 per &#956;L; hemoglobin (Hb.) 11,92; 12,60 and 12,97 g/dL; average corpuscular hemoglobin (HCM) 12,12; 12,16 and 14,1 pg. The plasmatic biochemical values referring to the researched ages were, respectively, glucose 79,09; 81,57 and 82,96 mg/dL; cholesterol of 42,37; 45,94 and 47,51 mg/dL; magnesium pf 1,90; 1,81 and 1,87 mg/dL; phosphorus of 7,47; 7,34 and 7,19 mg/dL; total calcium 11,37; 11,18 and 11,15 mg/dL; sodium of 155,11; 150,73 and 154,18 mEq/L; potassium of 4,86; 4,76 and 4,91 mEq/L. The hematologic values, according to sex, were respectively, hematocrit or globular volume (VG) 30,35 and 30,03%; average cospuscular hemoglobinic concentration (CHCM) 37,69 and 36,95 g/dL; erythrocytes of 9,03x106 and 10,25x106 per &#956;L; hemoglobin (Hb) 11,42 and 12,96 g/dL; average corpuscular volume (VCM) of 34,29 and 34,28 fL; leucocytes of 10,45 and 13,03 cel./ &#956;L; average cospuscular hemoglobin (HCM) 12,91 and 12,67 pg. The plasmatic biochemical values according to sex, were respectively, glucose of 82,37 snf 81,48 mf/dL; cholesterol of 44,03 and 46,44 mg/dL; magnesium of 1,87 and 1,85 mg/dL; phosphorus of 6,72 and 7,95 mg/dL; total calcium 11,13 and 11,31 mg/dL; sodium of 153,31 and 153,37 mEq/L; potassium of 4,74 and 4,94 mEq/L. The average hemogasometric values, corrected for he corporal temperature of 38ºC, according to the ages of 120, 180 and 240 days were, respectively, pH 7,45; 7,44 and 7,44; PaCO2 of 34,88, 34,65; 31,94 mmHg; PaO2 81,86; 77,68; 78,52 mmHg and BE 1,08 -1,78 and 0,13mEq/L. For the sex variable it was registered, respectively as pH of 7,45 and 7,38; PaCO2 pf 37,71 and 31,00 mmHg and PaO2 of 75,29 and 83,42 mmHg and BE 1,08 and 1,04 mEq/L. There was no meaningful difference (P<0,05) for the researched variables. The behaviorial data were obtained through visual observation, on the field, with interval of 5 minutes, during consecutive daily periods of 10 hours, in the experimental age bands, corresponding to the months from December 2003 to February and april 2004. Weighing was held at each 14 days, in a total of 15 trials. The scores of time spent in pasturing in the sun presented average values of 5,58; 5,00 and 1,70 h/day; the pasturing in the shadow consisted of average times of 1,70; 2,37 and 5,28 h/day xiii 14 and the rumination time in the shadow corresponded to 1,23; 1,88 and 1,77 h/day. The average values of daily weight gain, from birth to weaning and from weaning to the 240 days were, respectively, of 25,67 and 229,74 g/d. The data were analysed and delineation was entirely determined in factorial structure for sex and age. There was no effect (P<0,05) of interaction between age and sex, and from the sex factor to the analysed variables / Foram estudados os efeitos de idades aos 120, 180 e 240 dias, sobre o comportamento alimentar e o desempenho ponderal de treze cordeiros da raça Texel. O experimento foi realizado no Setor de Ovinocultura do CAV/UDESC em Lages, SC. Os cordeiros foram desmamados aos 60 dias e alimentados durante o dia, com água e sal mineral ad libitum, em piquete de 0,8 hectare com pastagem cultivada de trevo vermelho (Trifolium pratense L.) e trevo branco (Trifolium repens L.) e à noite eram estabulados em baias coletivas e suplementados com feno de alfafa (Medicago sativa L.). Os animais foram vermifugados e vacinados contra enterotoxemia. Foram obtidas amostras de 10 mL sangue venoso da veia jugular, sendo em 3 mL adicionado anticoagulante Etileno-diamino-tetracéticodissódico na concentração de 10%, utilizando-se 0,1mL em cada 5mL de sangue para os exames hematológicos e os restantes 7 mL foram deixados para que coagulasse e o soro do mesmo utilizado para as dosagens bioquímicas. Da artéria marginal da orelha, colheitou-se 1 mL de sangue para determinação dos valores hemogasométricos. Os valores hematológicos médios obtidos para as idades estudadas, foram, respectivamente,:hematócrito ou volume globular (VG) 32,50; 33,06 e 35,80%; concentração hemoglobínica corpuscular média (CHCM) 36,73; 37,02 e 38,09 g/dL; hemácias 9,86 × 106; 10,69 × 106 e 9,04 × 106 por &#956;L; hemoglobina (Hb) 11,92; 12,60 e 12,97 g/dL; volume corpuscular médio (VCM) 33,01; 32,90 e 36,81 fL; leucócitos 12.600; 10.730; 11.900 cel./&#956;L; hemoglobina corpuscular média (HCM) 12,12; 12,16 e 14,10 pg. Os valores bioquímicos plasmáticos referentes as idades estudadas foram, respectivamente,:glicose 79,09; 81,57 e 82,96 mg/dL; colesterol de 42,37; 45,94 e 47,51 mg/dL; magnésio de 1,90; 1,81 e 1,87 mg/dL; fósforo de 7,47; 7,34 e 7,19 mg/dL; cálcio total 11,37; 11,18 e 11,15 mg/dL; sódio de 155,11; 150,73 e 154,18 mEq/L; potássio de 4,86; 4,76 e 4,91 mEq/L. Os valores hematológicos, segundo o sexo, foram respectivamente, hematócrito ou volume globular (VG) 30.35 e 35,06%; concentração hemoglobínica corpuscular média (CHCM) 37,69 e; 36,95 g/dL; hemácias de 9,03 × 106 e 10,25 × 106 por &#956;L; hemoglobina (Hb) 11,42 e 12,96 g/dL; volume corpuscular médio (VCM) de 34,29 e 34,28 fL leucócitos de 10,45 e 13,03 cel./&#956;L; hemoglobina corpuscular média (HCM) 12,91 e 12,67 pg. Os valores bioquímicos plasmáticos segundo o sexo foram, respectivamente, glicose de 82,37 e 81,48 mg/dL; colesterol de 44,03 e 46,44 mg/dL; magnésio de 1,87 e 1,85 mg/dL; fósforo de 6,72 e 7,95 mg/dL; cálcio total 11,13 e 11,31 mg/dL; sódio de 153,31 e 153,37 mEq/L; potássio de 4,74 e 4,94 mEq/L. Os valores hemogasométricos médios, corrigidos para temperatura corporal de 38ºC, segundo as idades de 120, 180 e 240 dias foram, respectivamente: pH 7,45; 7,44 e 7,44; PaCO2 de 34,88; 34,65; 31,94 mmHg; PaO2 81,86; 77,68; 78,52 mmHg e BE 1,17, -1,78 e 0,13 mEq/L Para a variável sexo macho e fêmea registrou-se, respectivamente, pH de 7,45 e 7,38; PaCO2 de 37,71 e 31,00 mmHg e PaO2 de 75,29 e 83,42 mmHg e BE 1,08 e 1,04 mEq/L. Não houve diferença significativa (P<0,05) para as variáveis estudadas. Os dados comportamentais foram obtidos por observação visual, a campo, a cada cinco minutos, por três períodos diários consecutivos de dez horas, nas faixas etárias experimentais, correspondendo aos meses de dezembro de 2003, fevereiro e abril de 2004. Efetuaram-se pesagens a cada quatorze dias, totalizando quinze pesagens. Os tempos despendidos em pastejo ao sol, apresentaram valores xi 12 médios de 5,58; 5,00 e 1,70 h/dia; em pastejo à sombra, tempos médios de 1,70; 2,37 e 5,28 h/dia e tempo de ruminação à sombra de 1,23; 1,88 e 1,77 h/dia. Os valores médios de ganho de peso diário, do nascimento ao desmame e do desmame aos 240 dias foram, respectivamente, de 257,67 e 229,74 g/d. Os dados foram analisados em delineamento inteiramente casualizado em estrutura fatorial para sexo e idade. Não houve efeito (P<0,05) de interação entre idade e sexo e do fator sexo para as variáveis analisadas