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Two trials were conducted to demonstrate diet selected by grazing cattle. Selection criteria were investigated on the basis of cattle selection for plant species, green leaf in preference to dry leaf or dry stem and the chemical contents of esophageal samples versus those in the standing crop. The influence of residual old vegetation on selection ability was studied by mowing all or part of the pasture. Cattle consumed Lehmann lovegrass in preference to shrubby species (Table 1). The esophageal samples contained higher levels of protein, phosphorus and IVDMD than that in the standing crop in both Trial 1 and Trial 2. Neutral detergent fiber was higher in the standing crop than in the esophageal samples, whereas in Trial 2, there appeared to be no difference in NDF. Removal of old vegetation by mowing had no effect on selection for plant parts. Cattle selected green leaf, in preference to dry leaf or dry stem regardless of the presence of old material. Free ranging cattle selected a diet that was higher in nutrient density and more digestible than the available forage.

Thesis (PhDAgric (Animal Sciences))--Stellenbosch University, 2011. / ENGLISH ABSTRACT: A series of experiments were conducted to determine the effect of the replacement of oat silage by wheat straw in low forage diets for high producing dairy cows. In the first trial, 28 multiparous Holsteins were randomly assigned to two dietary treatments, namely silage and straw after completing a covariate period coinciding with the first 40 days of lactation and remained on these diets for the remainder of experimental period from 41 to 252 days. In order to evaluate the effect of substitution during different stages of lactation, the experimental period was divided into four phases. Diets were formulated to support similar levels of milk for both treatment groups and for all phases. The substitution of oat silage by wheat straw had a negative effect on dry matter intake, milk production and composition, as well as on feed and nitrogen efficiency, but had no effect on body weight and body condition. A rumen fermentation trial was also done, where six multiparous cannulated cows were randomly allocated in a changeover design to the same dietary treatments used in the animal performance trial. Despite a relatively low peNDF content and high NFC content of the diets, the mean rumen pH and time spent below pH 5.8 indicated that cows were actually not subjected to subclinical rumen acidosis, probably due to effective chewing activity. Forage source had no significant effect on rumen fermentation end products or mean daily rumen pH. However, the time spent below pH 5.8 was significantly lower for cows in the silage treatment than for those in the straw treatment, which could be related to a longer chewing time and more effective chewing activity that was observed on the straw treatment. Cows on the straw treatment sorted less against the medium sized particles, which was not expected, since straw inclusion is normally associated with a higher degree of sorting. In a third experiment, the effect of the replacement of silage by wheat straw was evaluated in terms of pre and postpartum animal performance. Dry cow diets were formulated with the objective to restrict intake, thus preventing cows from consuming metabolizable energy in excess of their requirements. Both treatments were successful in controlling intake and the replacement of oat silage by wheat straw in dry cow diets had no apprent effect on postpartum animal performance. Using the data from the lactation experiment, the adequacy of the CPM Dairy model to predict animal performance from low forage diets was also evaluated. The model was highly accurate in predicting adjusted milk production of cows consuming oat silage as basal forage, with a mean bias of only 0.05 kg milk/d, but it overpredicted milk production of cows receiving diets with wheat straw as the sole forage source, with a mean bias overprediction of 2.3 kg milk per day during the corresponding period of positive energy balance. Overprediction of energy balance from straw was confirmed in the dry cow experiment where a statistical analysis of the residuals between predicted and actual body condition score change indicated an overprediction on the straw treatment. / AFRIKAANSE OPSOMMING: Die invloed van die vervanging van hawerkuilvoer deur koringstrooi in diëte vir hoogproduserende melkkoeie is in ‘n reeks proewe nagegaan. In die eerste proef is 28 volwasse Holsteinkoeie ewekansig aan ‘n kuilvoer- of strooigebaseerde behandeling toegeken na die voltooiing van ‘n kovariaatperiode van 40 dae. Ten einde die invloed van die behandeling tydens verskillende stadia van laktasie te evalueer, is die proefperiode in vier fases verdeel. Diëte is geformuleer om vergelykbare melkproduksies vir beide behandelings tydens al die fases te ondersteun. Vervanging van hawerkuilvoer deur koringstrooi het ‘n negatiewe invloed op droëmateriaalinname, melkproduksie, melksamestelling, voeromset en stikstofbenutting gehad, maar geen invloed op ligaamsmassa- en kondisieverandering nie. In ‘n rumenfermentasieproef is ses volwasse, gekannuleerde Holsteinkoeie in ‘n omswaai-ontwerp aan twee diëte, soortgelyk aan dié wat tydens die laktasieproef gebruik is, in toegewys. Ten spyte van ‘n relatief lae peNDF-inhoud en ‘n relatief hoë NFC-inhoud van die diëte was daar, te oordeel aan die gemiddelde rumen pH en tyd waartydens die rumen pH onder 5.8 was, geen aanduiding van subkliniese rumenasidose nie, waarskynlik as gevolg van ‘n langer kou-tyd en meer doeltreffende kouaktiwiteit. Ruvoerbron het skynbaar ook geen invloed op rumenfermentasie-eindprodukte en gemiddelde rumen pH gehad nie. Die periode waartydens rumen pH laer as 5.8 was, was egter korter vir koeie in die kuilvoerbehandeling as vir dié in die strooibehandeling. Dit kan waarskynlik aan meer doeltreffende herkou-aktiwiteit toegeskryf word. Aangesien strooiinsluiting in herkouerdiëte normaalweg met ‘n groter mate van voerseleksie geassosieer word, was die kleiner mate van seleksie teen mediumgrootte partikels met die strooibehandeling verrassend. In ‘n derde proef is die invloed van van die vervanging van kuilvoer met koringstrooi in terme van pre- en postpartum diereprestasie ondersoek. Droëkoeidiëte is geformuleer met die doel om inname te beperk en koeie sodoende te verhoed om meer metaboliseerbare energie in te neem as wat hulle benodig. Albei behandelings was doeltreffend om inname te beheer en die vervanging van hawerkuilvoer met koringstrooi het geen invloed op postpartum diereprestasie gehad nie. Deur van die data van die laktasieproef gebruik te maak, is die toereikendheid van die CPM Dairy model om diereprestasie vanaf lae ruvoerdiëte te voorspel, ook bepaal. Die model was hoogs akkuraat in die voorspelling van melkproduksie in die geval van die kuilvoerbehandeling, maar dit het melkroduksie met 2.3 kg/dag oorskat in die geval van die koringstrooibehandeling. Hierdie oorberaming van energiebalans is tydens die droëkoeiproef bevestig.

Orientador: Mário De Beni Arrigoni / Coorientador: Cyntia Ludovico Martins / Banca: José Luís Moraes Vasconcelos / Banca: Ciniro Costa / Banca: Rodrigo Dias Lauritano Pacheco / Banca: Sérgio Raposo de Medeiros / Resumo: O objetivo deste estudo foi avaliar os efeitos da duração de protocolos de adaptação às dietas com alta inclusão de concentrados sobre o desempenho, características de carcaça (CC), comportamento ingestivo (CI) e variação diária na ingestão de matéria seca (VDIMS) de bovinos Nelore terminados em confinamento. O delineamento experimental foi em blocos inteiramente casualizados, em arranjo fatorial 2 × 2, sendo os fatores protocolos de adaptação (escadas e restrição) e tempo de durações dos mesmos (9 e 14 dias), totalizando 24 baias, com 6 repetições (baia) por tratamento (5 animais/baia), com 120 Nelores machos não castrados (361,3 ± 30,2 kg), distribuídos em 6 blocos. Foi observado para os animais do protocolo de restrição menor ingestão de matéria seca (IMS) em quilogramas no período de 0 a 28 dias (P=0,01) e 0 a 56 dias (P=0,10) (9,01 vs. 9,67 e 10,18 vs. 10,66), menor IMS em porcentagem de peso vivo (PV) no período de 0 a 28 dias (P=0,01) e 0 a 56 dias (P=0,03) (2,36 vs. 2,52 e 2,47 vs. 2,58). Para conversão alimentar, eficiência alimentar e custo para ganhar um quilo de PV, os animais do protocolo de restrição tiveram melhores valores no período de 0 a 56 dias (P=0,06) e 0 a 84 dias (P=0,04) (0 a 56 dias: 5,61 vs. 5,97; 0,179 vs. 0,169 e 3,32 vs. 3,53 - 0 a 84 dias: 6,08 vs. 6,38; 0,165 vs. 0,157 e 3,59 vs. 3,77). Foi observado (P=0,0056) efeito principal de protocolo na VDIMS, com maiores valores para os animais adaptados pelo protocolo em escadas na fase de adaptação (0,524 vs. 0,438). No CI, animais do protocolo de restrição apresentaram menor tempo de ruminação (TR) (P<0,01) (304,00 min/d vs. 398,59 min/d), idas ao bebedouro (IB) (P=0,03) (7,40 vs. 8,32), tempo de alimentação por refeição (P<0,01) (5,47 min vs. 7,41 min) e eficiência de ruminação da MS (ERUMS) (P<0,01) (41,93 min/kg vs. 47,76 min/kg)... (resumo completo, clicar acesso eletrônico abaixo) / Abstract: One hundred and twenty, 24-mo-old Nellore bulls (361.3±30.2 kg) were fed in 24 pens for 84-d to determine effects of adaptation protocol and length period on feedlot performance, carcass traits, feeding behavior and dry matter intake fluctuations (DMIF) of Nellore cattle. A completely randomized block design with a 2×2 factorial arrangement and 6 replications was used (5 bulls/pen). Factors include adaptation protocols, restricted finishing diet intake (REST) as a means of dietary adaptation compared with diets increasing in concentrate (STEP) over periods of either 9 or 14 d. Low dry matter intake (DMI) in kilograms for the REST animals in the period from 0 to 28 days (P=0.01) and 0 to 56 days (P=0.10) (9.01 vs 9.67 and 10.18 vs. 10.66) as well as low DMI in percentage of body weight (BW) in the period from 0 to 28 days (P=0.01) and 0 to 56 days (P=0.03) (2.36 vs 2.52; 2.47 vs. 2.58) were observed. REST animals showed better values in the period from 0 to 56 days (P=0.06) and 0 to 84 days (P=0.04) in feed conversion, feed efficiency and cost to gain one kilogram of BW (0 to 56 days: 5.61 vs 5.97, 0.179 vs 0.169 and 3.32 vs 3.53 - 0 to 84 days: 6.08 vs 6.38, 0.165 vs 0.157 and 3.59 vs 3.77). STEP animals presented (P=0.0056) higher DMIF at adaptation phase (0.524 vs 0.438). Regarding feeding behavior, REST animals presented lower chewing time (P<0.01) (304.00 min/d vs 398.59 min/d), lower number of visits to drink water (P=0.03) (7.40 vs 8.32), less meal time (P<0.01) (5.47 min vs 7.41 min) and lower chewing dry matter efficiency (P<0.01) (41.93 min/kg vs 47.76 min/kg). Moreover, interaction between protocol and days (P<.0001) to daily feed time, total chewing time, inactivity time, DMI and daily feed efficiency of dry matter was observed, in which REST animal provided the best values along the observation days... (Complete abstract click electronic access below) / Doutor

Orientador: Dirlei Antonio Berto / Coorientador: Marcos Livio Panhoza Tse / Banca: José Roberto Sartori / Banca: Angélica Simone Cravo Pereira / Resumo: O objetivo do presente estudo foi avaliar os efeitos do aumento do nível de triptofano na dieta de leitões desmamados submetidos a diferentes programas de luz. Foram utilizados 72 leitões desmamados aos 21 dias de idade (peso inicial de 6,6+ 2,33 kg). O delineamento experimental foi o de blocos casualisados com 24 dias de duração em esquema fatorial 2 x 2 (PL: 12 ou 23h de luz/dia e dois NT digestível: 2,6 ou 5,2 g de L-Trp / kg de ração pré-inicial 1 (0-14 dias) e de 2,4 ou 4,8 g de L-Trp / kg na dieta pré-inicial 2 (15-24 dias), com 6 repetições e 3 animais por parcela. Foram avaliados o desempenho, glicemia, perfil plasmático do cortisol e comportamento dos animais. A glicose no sangue foi determinada nos dias 0 e 24, e o cortisol nos dias 0 e 8. O comportamento foi observado nos dias 2, 9, 16 e 23. Não houve interação entre PL e NT sobre desempenho e glicose. Nos períodos de 0-14 e 0-24 dias, os tratamentos não influenciaram o ganho diário de peso, consumo diário de ração e glicose no sangue, enquanto que a conversão alimentar melhorou (P<0,05) apenas no período de 0-14 dias para os animais que receberam 12 horas de luz/dia. Os tratamentos não influenciaram a frequência do comportamento "em movimento", entretanto houve interação entre PL e NT para o cortisol plasmático, frequência dos comportamentos "ócio" e "alimentar". Leitões que receberam o maior NT apresentaram menor nível de cortisol plasmático (P<0,05), menor comportamento "alimentar" (P<0,05) e maior comportamento "ócio" (P<0,05) em relação aos animais que receberam NT normal quando submetidos ao PL de 23 horas de luz/dia. O uso de PL de 23h de luz/dia não é indicado, entretanto, quando este manejo for adotado o maior nível de triptofano na dieta ... / Abstract: The objective of the present study was to avaluate the effects of light programs (LP) and tryptophan levels (TL) in the diet on performance, blood glucose, plasma profile of cortisol and behavior. A total of 72 piglets weaned at 21 days of age (starting weight 2.33 kg 6,6±) was used. The experimental design was randomized blocks with 24 days duration in a factorial 2 x 2 (LP 12 or 23h light / day and two digestible TL: 2.6 or 5.2 g of L-Trp / kg diet on pre-starter 1 (0-14 days) and 2.4 or 4.8 g of L-Trp / kg diet on prestarter 2 (15-24 days), with 6 repetitions and 3 animals per pen. Glucose blood was determined on d 0 and 24, and cortisol on d 0 and 8. The behavior was observed on d 2, 9, 16 and 23. No effects of PL and NT interaction were observed on performance and blood glucose. In periods of 0- 14 and 0-24 days, the treatments did not influence the daily weight gain, daily feed intake and blood glucose, while feed conversion improved (P <0.05) only in the period of 0-14 days for piglets receiving PL 12h light / day. Treatments did not influence the frequency of "moving" behavior, however there was interaction between PL and NT for plasma cortisol, frequency of "feeding" and "lying" behavior. Piglets that received high NT had lower plasma cortisol level (P <0.05), lower "feeding" behavior (P <0 .05) and increased "lying" behavior (P <0.05) compared to animals that received normal NT when subjected to PL 23 hours light / day. The PL 23h light / day isn't indicated for piglets, but when this happen, highest tryptophan level in the diet is recommended. / Mestre

Orientador: André Mendes Jorge / Banca: Paulo Roberto de Lima Meirelles / Banca: Cristiana Andrighetto / Resumo: Objetivou-se com esse estudo avaliar o método de suplementação de 20 bovinos [(Nelore; 10 + 1 mês de idade e 220 + 33kg de peso vivo (PV) iniciais] e 20 bubalinos [Murrah; 10 + 1 mês de idade e 206 + 29kg (PV) iniciais] recriados em pasto de Urochloa brizantha cv. Xaraés, suplementados (0,6% PV) ou não (controle). Foram realizadas pesagens dos animais no início do estudo (0d) e nos dias 28, 56 e 84, para o cálculo do ganho de peso (GP), ganho médio diário (GMD), e coletas de amostras de sangue para determinação da glicose plasmática. Medidas da altura de garupa (AG), escore de condição corporal (ECC), área de olho de lombo (AOL), espessura de gordura subcutânea (EGS; 12a costela) e espessura de gordura da garupa (EGG) foram determinadas no início (0d) e no final (84d) do estudo. Foi realizada avaliação do comportamento ingestivo (tempo no cocho, ruminação, ócio e ingestão de água) considerando o tempo dispendido com cada evento. Custos dos diferentes tratamentos foram calculados. Não houve interação entre espécie e tratamento. Os bovinos apresentaram valores superiores (P < 0,01) de PV0d, PV28d, PV56d, PV84d, GPtotal, GMD28d, GMD56d, GMD84d, GMDtotal, AG0d, AG84d, AOL84d (P = 0,04), custo total/cabeça (P = 0,03) e lucro/cabeça/ha, quando comparados aos bubalinos. Enquanto que maiores valores (P < 0,01) de ECC0d, ECC84d, EGS0d, EGS84d, EGG0d, EGG84d, tempo de permanência no cocho, quantidade de água ingerida (P < 0,01), e consumo percentual de suplemento foram atribuídos aos bubalinos. Foi detectado efeito do tratamento (P < 0,01) para as características de PV0d, PV28d, PV56d, PV84d, GPtotal, GMD28d, GMD56d, GMD84d, GMDtotal, ECC84d, AOL84d, custo total/cabeça, ganho/@, receita/cabeça, para as quais os animais suplementados apresentaram maiores valores quando comparados aos animais controle. Conclui-se que o grupo genético bovino se destacou quanto aos ganhos de ... / Abstract: The objective of this study was evaluate the supplementation method of 20 beef cattle [Nelore; 10 + 1 month of age and 220 + 33kg body weight (BW)] and 20 buffaloes [Murrah water buffalo, 10 + 1 month of age and 206 + 29kg body weight (BW)] growing in (Urochloa brizantha cv. Xaraés) receiving supplementation (0.6% BW), or not (control). Animals were divided in two treatment groups (n = 10 animals of each genetic group for each treatment). Body weight were conducted at the beginning of the experiment (0d) and 28, 56 and 84 day, to determining weight gain (WG), average daily gain (ADG), and blood samples for determination of glucose. Hip height measurements (HH), body condition score (BCS), rib eye area (REA), backfat thickness - 12th rib (BF), rump fat thickness (RFT) were determined at the beginning (0d) and the end (84d) of the study. The evaluation of feeding behavior was conducted (trough time, rumination, idleness and water intake) considering the time spent on each event. Cost of different treatments was calculated. There was no interaction between species and treatment.The beef cattle had higher values (P <0.01) of BW0d, BW28d, BW56d, BW84d, WGtotal, ADG28d, ADG56d, ADG84d, ADGtotal, HH0d, HH84d, REA84d (P = 0.04), total cost/head (P = 0.03) and income/head/ha when compared to buffaloes. Buffaloes had higher values (P < 0.01) of BCS0d, BCS84d, BF0d, BF84d, RFT0d, RFT84d, length of stay in the trough, water intake, and percentage supplement intake compared to beef cattle. Effect of treatment was detected (P < 0.01) for BW0d, BW28d, BW56d, BW84d, WGtotal, ADG28d, ADG56d, ADG84d, ADGtotal, BCS84d, REA84d, total cost/head, gain/@, income/head where supplemented animals showed higher values when compared to control animals. In conclusion, bovine genetic group excelled for weight gains while consuming a smaller proportion of ... / Mestre

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