Forage of beta-carotene-fortified orange-fleshed sweet potato is essential for alleviation cattle malnutrition. The study aims were to determine effects of supplementing sweet potato (SP) roots and sun dried forage on degradation of dietary legumes, intake and milk yield in dairy cattle. Mature SP roots were oven dried and forage vines and leaves (V&L) sun dried. Lactating dairy were supplied meals with total mixed ration (TMR) constituting varying levels of sweet potato forage and concentrate. The SP flour was rapidly and completely degraded In Sacco while degradability of V&L was comparable to that of Lucerne hay. Rumen degradation of Lucerne was reduced when the legume was incubated proximal to SP. Substitution of TMR with fresh SP forage and flour meal increased degradability of diets. Glucose post-feeding was increased (P<0.05) by SP roots but no change in milk yield. Orange-fleshed SP forage is recommended for improving energy supply in lactating cow diets / Agriculture and  Animal Health / M. Sc. (Agriculture)

Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Grinding of feedstuffs prior to in sacco incubation results in fine particles that could escape from dacron bags without being degraded. The objective of this study was to determine the effect of the removal of these fine particles on protein degradation parameters. The feedstuffs that were used were protein feedstuffs that are commonly used in dairy cattle diets in South Africa. Feedstuffs were soybean oilcake, sunflower oilcake, maize gluten 20, maize gluten 60 and fish meal. Treatments were; 1. grinding through a 2 mm screen with no subsequent sieving, 2. grinding through a 2 mm screen followed by sieving through a 106 μm mesh, and 3. grinding through a 2 mm screen followed by sieving through a 150 μm mesh. In the first trial, the material that was lost through sieving and the chemical composition of the different treatments were determined. Protein solubility was also determined. Between 20 and 60% of the material dry matter was lost with the sieving. The chemical composition for the soybean and sunflower oilcake and maize gluten 60 was similar between the three different treatments (or fractions). The CP content of fish meal and maize gluten 20 differed somewhat between the treatments. The 106 μm mesh seemed to be most suitable for fish meal, but a suitable mesh size could not be found for maize gluten 20. In the second trial, the degradability parameters were determined according to the in sacco degradation procedure. Three lactating Holstein cows that were fitted with rumen cannulae were used. The cows received a commercial lactation diet and oat hay that was supplied ad libitum. Samples of all the protein sources were placed in dacron bags and incubated in the rumen. The following removal times were used: 0, 2, 4, 8, 12, 24 or 48 hours. Dry matter and CP disappearances were determined, and the values were used to estimate DM and CP degradability parameters using a non-linear model. Effective CP degradability was also determined. The a-values were affected most of all. On average, the a-values were 39.4 and 40.3% higher for the un-sieved treatments than for the sieved treatments, for DM and CP, respectively. The effective CP degradability was also, on average, 43% higher for the un-sieved treatments. Grinding without the subsequent sieving of samples appears to result in an overestimation of DM and CP degradation in the rumen. It is therefore recommended that after grinding, feedstuffs should be sieved through at least a 106 μm mesh in preparation for in sacco incubations. / AFRIKAANSE OPSOMMING: Die maal van grondstowwe ter voorbereiding van in sacco inkubasies lei tot ‘n potensiële verlies van klein partikels uit die dakronsakkies sonder dat hulle gedegradeer word. Die doel van hierdie studie was om die invloed van die verwydering van fynmateriaal op proteïen-degradeerbaarheidsparameters te bepaal. Die grondstowwe wat in hierdie studie gebruik is, is proteïengrondstowwe wat algemeen in melkbeesdiëte in Suid-Afrika gebruik word. Die grondstowwe was soja-oliekoek, sonneblom-oliekoek, mielie gluten 20, mielie gluten 60 en vismeel. Behandelings was; 1. maal deur ‘n 2 mm sif sonder verdere sifting, 2. maal deur ‘n 2 mm sif gevolg deur sifting deur ‘n 106 μm sif en 3. maal deur ‘n 2 mm sif gevolg deur sifting deur ‘n 150 μm sif. In die eerste proef is die hoeveelheid materiaal wat verlore gaan as gevolg van sifting van die grondstowwe bepaal en die chemiese samestelling van die verskillende behandelings. Proteïenoplosbaarheid is ook bepaal. Tussen 20 en 60% van die materiaal het verlore gegaan as gevolg van sifting. Die chemiese samestelling van die soja- en sonneblom oliekoek, asook dié van die mielie gluten 60 was soortgelyk vir al drie die behandelings. Die ruproteïeninhoud (RP) van die vismeel en mielie gluten 20 het verskil tussen die drie behandelings. Dit wil voorkom asof die 106 μm sif die mees geskikte is vir vismeel, maar ‘n geskikte sif kon nie vir mielie gluten 20 gevind word nie. In die tweede proef is die degradeerbaarheidsparameters bepaal met behulp van die in sacco-metode. Drie lakterende Holsteinkoeie met rumen kannulas is gebruik. Die koeie het ‘n kommersiële melkbeesdieët ontvang en hawerhooi ad libitum. Die monsters is in dakronsakkies in die rumen geïnkubeer. Die sakkies is na die volgende inkubasietye verwyder: 0, 2, 4, 8, 12, 24 of 48 uur. Die DM- en RP-verdwyning is bereken en die waardes is gebruik om die DM- en RP- degradeerbaarheidsparameters te bereken met behulp van ‘n nie-lineêre model. Effektiewe RP- degradeerbaarheid is ook bereken. Die waardes wat die meeste beïnvloed is, is die a-waardes. Die a-waardes was gemiddeld 39.4 en 40.3% hoër vir die ongesifte behandelings as vir die gesifte behandelings, vir DM en RP, onderskeidelik. Die effektiewe RP-degradeerbaarheid was ook gemiddeld 43% hoër vir die ongesifte behandelings. Dit wil voorkom asof DM- en RP-degradeerbaarheid oorskat word wanneer voermonsters slegs gemaal word. Dit word aanbeveel dat grondstowwe ten minste deur ‘n 106 μm sif gesif word ter voorbereiding vir in sacco-studies.

Thesis (MScAgric)--Stellenbosch University, 2012 / ENGLISH ABSTRACT: Ruminal pH is the rumen condition that varies most. Studying the cause and effect of diurnal variation offers a means of improving ruminal conditions for rumen micro-organisms with subsequent improvements in fibre degradation, milk yields and milk composition. A research project was conducted to test the following hypothesis: feeding 6 kg (as is) concentrate per cow/day in different weight ratios, divided in a morning and an afternoon allocation, will result in an improved ruminal pH profile and a concurrent increase in fibre fermentation, milk yield and improved milk composition. The project was conducted at the Outeniqua Research Farm in the Southern Cape of South Africa. A randomized block design was used and two phases, viz. ryegrass phase and a kikuyu phase, were applied. Each phase was conducted during the growing season of the grass specie used as pasture. A rumen study and a production study were done in each phase. The rumen study used six cannulated multiparous cows per treatment, testing rumen pH, volatile fatty acid (VFA) concentration, in sacco degradation of neutral detergent fibre (NDF) and dry matter (DM). The production study used 42 multiparous cows, blocked according to days in milk (DIM), parity and milk yield, and cows were randomly divided into three treatment groups. The study tested milk yield, milk composition and changes in body weight (BW) and body condition score (BCS). Treatments consisted of a maize based concentrate supplement (6 kg per cow/day, as is) being fed to cows on pasture in different weight ratios between morning and afternoon allocation. Treatments used in the production study were: Concentrate fed: 5 kg during morning; 1 kg during afternoon • Concentrate fed: 4 kg during morning; 2 kg during afternoon • Concentrate fed: 3 kg during morning; 3 kg during afternoon The first and the last treatments mentioned above were used in the rumen studies. Results of the rumen study of the ryegrass phase showed no differences in ruminal pH between treatment means. The time (h) spent below the critical ruminal pH, i.e. 5.8, was of short duration (2.92 to 3.42 hours). The concentration of certain VFA’s differed at times, but the differences were not reflected in graphs and data of the ruminal pH. No differences were observed in in sacco NDF and DM degradation between treatment means. Similar results were mostly obtained in the kikuyu phase. No differences were found in either daily maximum, minimum or mean ruminal pH between treatment means. Though time (h) spent below the critical ruminal pH was of a long duration (7.1 hours) it did not differ between treatments. No differences were observed between treatment means for in sacco NDF and DM degradation. Results of the production study of the ryegrass phase showed no differences in milk yield or milk composition between treatment means. The same was observed in the kikuyu phase except that milk fat was higher in the treatment group that received the 3:3 kg ratio treatment. The fact that treatments did not differ in terms of milk yield and milk composition in the production studies can be attributed to no differences between treatments in terms of rumen parameters observed in the rumen studies. Thus, feeding a higher proportion of concentrate in the morning relative to the afternoon for a total of 6 kg per cow/day does not affect ruminal pH, fibre digestion or milk production. Based on the results of both phases it can be concluded that the null hypothesis should be rejected. / AFRIKAANSE OPSOMMING: Die invloed van kragvoer voedingsstrategieë op rumen parameters, melkproduksie en melksamestelling van Jerseykoeie op raaigras- (Lolium multiflorum) of kikoejoe- (Pennisetum clandestinum) weidings. Die invloed van kragvoer voedingsstrategieë op rumen parameters, melkproduksie en melksamestelling van Jerseykoeie op raaigras- (Lolium multiflorum) of kikoejoe- (Pennisetum clandestinum) weidings. Behandelings toegepas in die produksiestudie het bestaan uit ‘n kragvoeraanvulling met ‘n mieliebasis wat aan koeie op weidings gevoer is in verskillende gewigsverhoudings tussen oggend- en middagvoeding, as volg: Behandelings toegepas in die produksiestudie het bestaan uit ‘n kragvoeraanvulling met ‘n mieliebasis wat aan koeie op weidings gevoer is in verskillende gewigsverhoudings tussen oggend- en middagvoeding, as volg:

Thesis (MScAgric)--Stellenbosch University, 2002. / ENGLISH ABSTRACT: The objectives of this study were to determine the effects of supplementing oat silage (OS) with lucerne (LH) and oat hay (OH) on the production performance of lactating Jersey cows, as well as comparing the ruminal degradability of LH, OH and OS III Holstein and Jersey cows receiving a high forage diet and a high concentrate diet. In the first trial, five diets containing different combinations of OS and LH together with concentrate mixtures providing 26, 23, 20, 17 and 14% crude protein (CP) were fed to lactating Jersey cows. Lucerne hay was fed at 0, 2, 4, 6, and 8 kg DM/day while OS was fed ad libitum. Cows receiving only OS as a forage source had a lower (P<0.05) dry matter (DM) intake and produced less milk protein (P<0.05). Milk and fat yields as well as milk urea nitrogen (MUN) levels did not differ (P>0.05) between treatments. In the second trial, OS was fed with OH and a concentrate mixture containing 26% CP to lactating Jersey cows. Oat hay was fed at 0, 2, 4, 6, and 8 kg DMiday while OS was fed ad libitum. Cows that received OS together with 4 and 6kg OH, respectively had higher (P<0.05) DM intakes. Milk, fat, and protein yields as well as MUN levels did not differ (P>O.05) between treatments. The ruminal degradability of LH, OH and OS in Holstein and Jersey cows receiving (i) a high forage and (ii) a high concentrate diet was determined. The two breeds were also compared in terms of rumen pH levels, volatile fatty acids (VF A) and rumen ammonia nitrogen (NH3-N) concentrations as affected by time after feeding. The ruminal degradability of freeze dried (FD), oven dried (OD) and fresh oat silage (FS) in Jersey cows receiving a high forage diet was also determined. The ruminal DM, CP and NDF degradability of LH was higher (P<O.05) than that of OH and OS in both Holstein and Jersey cows when they were fed either a high forage or a high concentrate diet. When cows were fed a high forage diet, the effective DM degradability of OS was higher (P<O.05) in Holsteins although the CP degradation rates of LH and OH were higher (P<O.05) in Jerseys. When they were fed a high concentrate diet, Jerseys had higher (P<O.05) effective DM and NDF degradabilities and higher (P<O.05) DM and NDF degradation rates in LH while Holsteins had higher (P<O.05) effective CP degradability levels than Jerseys in OS. After feeding a high forage diet, pH levels declined while VFA and NH3-N concentrations increased (P<O.05) in both breeds. Jerseys had higher rumen pH, lower (P<O.05) VFA and lower NH3-N concentrations than Holsteins throughout the study. When cows were fed a high concentrate diet, Jerseys had higher (P<O.05) pH than Holsteins. A post-feeding decline (P<O.05) in pH was observed in both breeds. Fresh oat silage had a lower (P<O.05) effective degradability and degradation rates for DM, CP and NDF in comparison to FD and OD oat silage. The DM, CP and NDF degradation rates, as well as effective NDF degradability were higher (P<O.05) for FD silage, but effective DM and CP degradabilities were higher (P<O.05) for OD oat silage. It was concluded that on an oat silage diet, lactating Jersey cows should receive a minimum of 2kg LH or 4 to 6kg oat hay together with ad libitum OS to improve DM intake. When cows were fed a high concentrate diet, the ruminal degradability appeared to be superior in Jerseys than Holsteins. Jerseys also had higher rumen pH levels lower VFA and NH3-N concentrations than Holsteins. Feeding interval affects the rumen environment, pH declines while VF A and NH3-N concentrations increased. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die effek van die aanvulling van hawerkuilvoer met lusemhooi (LH) en hawerhooi (HH) op die melkproduksie van Jerseykoeie te bepaal. Hiermee saam is die rumen degradeerbaarheid van hawerkuilvoer en lusemhooi ondersoek in Jersey en Holsteinkoeie wat 'n hoe-ruvoer en 'n hoe-kragvoer gebaseerde dieet ontvang het. In die eerste proef is vyf diete met verskillende peile van hawerkuilvoer en lusernhooi saam met kragvoere van verskillende ruproteienpeile (26, 23, 20, 17 en 14% RP) aan 10 lakterende Jerseykoeie gevoer. Hawerkuilvoer is ad libitum voorsien en lusemhooi is teen vlakke van 0, 2, 4,6 en Skg droemateriaal (DM) per dag gevoer. Die DM-inname en melkproteienproduksie van koeie wat hawerkuilvoer as die enigste ruvoerbron ontvang het, was laer (P<0.05) as ander ruvoerkombinasies. Die melk- en vetproduksie, asook melk-ureumstikstofpeile het nie tussen behandelings verskil nie (P>0.05). In die tweede proef is hawerkuilvoer saam met hawerhooi (soortgelyk as Proef 1) gevoer. Die kragvoerkomponent van al die ruvoerkombinasies het 26% RP bevat. Die koeie wat hawerkuilvoer en 4 of 6kg hawerhooi as ruvoere ontvang het, het hoer (P<O.05) droemateriaalinnames gehad. Melk, vet en proteienproduksie asook melk-ureumstikstofpeile het nie tussen ruvoerkombinasies verskil nie (P>O.05). Die rumendegradeerbaarheid van lusemhooi, hawerhooi en hawerkuilvoer is bepaal in Holstein en Jerseykoeie wat (i) 'n hoe ruvoer- en (ii) 'n hoe kragvoerdieet ontvang het. Die rumen pH, vlugtige vetsuur en rumen-ammoniakkonsentrasies, soos beinvloed deur tyd na voeding, is ook tussen rasse vergelyk. Die rumendegradeerbaarheid van vars, oondgedroogde en vriesgedroogde hawerkuilvoer is ook bepaal. Die rumen DM, RP en NDF degradeerbaarhede van lusemhooi was hoer (P<O.05) as by hawerhooi en hawerkuilvoer in beide Holstein en Jerseykoeie wat (i) 'n hoe ruvoer- en (ii) 'n hoe kragvoerdieet ontvang het. Op 'n hoe ruvoerdieet, was effektiewe DM degradeerbaarheid van hawerkuilvoer by Holsteins hoer (P<O.05) as by Jerseys. Jerseykoeie het egter 'n hoer (P<O.05) RP degradeerbaarheidstempo van lusemhooi en hawerhooi gehad. Jerseykoeie op 'n hoe kragvoerdieet, het hoer (P<O.05) effektiewe DM en NDF degradeerbaarhede getoon. Hulle het egter 'n laer (P<O.05) effektiewe ruprotein (RP) degradeerbaarheid by hawerkuilvoer as Friese gehad. Jerseykoeie op lusemhooi het ook 'n hoer (P<O.05) DM en NDF degradeerbaarheidstempo getoon. Jerseykoeie wat 'n hoe ruvoerdieet ontvang het, het 'n hoer (P<O.05) rumen- pH en laer (P<O.05) vlugtige vetsuur- en rumen-ammoniak konsentrasies as Holsteinkoeie gehad. Jerseykoeie wat 'n hoe kragvoerdieet ontvang het, het ook 'n hoer (P<O.05) rumen- pH as Holsteinkoeie gehad. By al die koeie is gevind dat rumen- pH na voeding afgeneem het (P<O.05). Vlugtige vetsuur- en rumen-ammoniakkonsentrasies was laag voor voeding en het daama toegeneem (P<O.05). Vars hawerkuilvoer het laer (P<O.05) effektiewe DM, RP en NDF degradeerbaarhede en degradeerbaarheidstempo's as oond- en vriesgedroogde hawerkuilvoer gehad. Die vriesgedroogde kuilvoer het hoer (P<O.05) DM, RP en NDF degradeerbaarheidstempo's sowel as effektiewe NDF degradeerbaarhede gehad. Oondgedroogde kuilvoer het daarinteen hoer (P<O.05) effektiewe DM en RP degradeerbaarhede gehad. Die gevolgtrekking is gemaak dat lakterende Jerseykoeie ten minste 2kg lusemhooi of 4- 6kg hawerhooi per dag moet ontvang wanneer hulle hawerkuilvoer as ruvoerbron ontvang. Op 'n hoe kragvoerdieet, het dit gebleik dat die rumendegradeerbaarheid van vesel by Jerseys beter is as by Holsteins. Die rumen- pH is hoog voor voeding, maar dit neem af nadat die koeie gevreet het. Die rumen- pH van Jerseys was hoer as by Holsteins. Die vlugtige vetsure en rumen-ammoniakkonsentrasies blyk laag te wees voor voeding en neem daama toe. Konsentrasies was hoer by Holstein as by Jerseys.

No description available.

Orientador: Alexandre Secorun Borges / Banca: Márcio Rubens Graaf Kuchembuck / Banca: Ivan Roque de Barros Filho / Resumo: O presente trabalho teve como objetivo determinar os elementos minerais no soro sangüíneo (magnésio, cobre, selênio, zinco, fósforo, cálcio, potássio, ferro) e no tecido hepático (cobalto, cobre, selênio, manganês, molibdênio e zinco) em seis diferentes momentos durante um período de dezesseis meses e verificar se houve variação entre eles. Foram utilizadas 25 novilhas mestiças Nelore, com idade média de 18 meses, que permaneceram durante todo o tempo do experimento no mesmo pasto de Brachiaria brizantha. Os animais ainda receberam mistura mineral comercial em cocho coberto e água à vontade e foram submetidos à coleta de fragmentos hepáticos e sangue para obtenção de soro. Análises da pastagem também foram realizadas nos mesmos momentos em que foram colhidas as amostras de soro e fígado (exceto em fevereiro 2003). A água e o sal mineral também foram analisadas. Os níveis médios dos elementos no tecido hepático foram, respectivamente para as seis diferentes colheitas: Co 0,27;0,27; 0,23;0,21; 0,23 e 0,24 ppm; Mn 9,07; 8,55; 8,67; 8,40; 7,90 e 7,25 ppm; Mo 4,18; 3,85; 3,68; 3,32; 3,54; 3,19 ppm; Zn 113,4; 101,94; 97,91; 92,46; 88,29 e 81,74 ppm; Cu 40,76; 36,33; 24,50; 24,70; 77,75 e 128,03 ppm e Se 0,86; 1,09; 0,72; 1,21; 0,91 e 0,75 ppm. Destes, os níveis de Co, Mn, Mo, Se e Zn foram considerados adequados para bovinos. Os níveis médios dos elementos no soro foram, para as quatro diferentes colheitas: Ca 118,72; 129,36; 125,19; 112,90; 96,76; 85,37 mg/L; P 109,28; 106,30; 117,03; 103,39; 115,78 e 107,75 mg/L; Mg 19,75; 23,62; 26,54; 20,96; 20,80 e 23,12 mg/L; K 139,64; 134,85; 114,19; 131,65; 130,57 e 116,60 mg/L; Cu 0,52; 0,73; 0,41; 0,59; 0,60 e 0,73 mg/L; Zn 1,19; 1,87; 1,38; 1,13;1,28 e 1,37 mg/L; Fe 2,52; 3,44; 2,21; 3,08; 3,00 e 2,89 mg/L e Se 1,19; 1,87; 0,19; 0,44, 0,40 e 0,51 mg/L...(Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The objective of the present work was to determinate the mineral levels in beef cattle blood serum (magnesium, copper, selenium, zinc, phosphorus, calcium, potassium, iron) and liver (cobalt, copper, selenium, manganese, molibdenium and zinc) at six different moments throughout sixteen months, to verify the occurrence of variation among them. Twenty-five half-breed nelore heifers, all of them about 18 months old, stayed during the experiment in the same Brachiaria brizantha pasture. They also received commercial mineral mixture in appropriate feeders and free acess to water. Pasture were also analised at the same moments we did for serum and liver (except february 2003). Water and mineral mixture were analised as well. The average levels of the elements in the liver, respectively for the six different moments: Co 0.27,0.27, 0.23, 0.21, 0.23 and 0.24 ppm; Mn 9.07, 8.55, 8.67, 8.40, 7.90 and 7.25 ppm; Mo 4.18, 3.85, 3.68, 3.32, 3.54, 3.19 ppm; Zn 113.4, 101.94, 97.91, 92.46, 88.29 and 81.74 ppm; Cu 40.76, 36.33, 24.50, 24.70, 77.75 and 128.03 ppm and Se 0.86, 1.09, 0.72, 1.21, 0.91 and 0.75 ppm. The levels of Co, Mn, Mo, Se and Zn were considered appropriate for cattle. The average levels of the elements in the serum were, for the six different moments: Ca 118.72, 129.36, 125.19, 112.90, 96.76, 85.37 mg/L; P 109.28, 106.30, 117.03, 103.39, 115.78 and 107.75 mg/L; Mg 19.75, 23.62, 26.54, 20.96, 20.80 and 23.12 mg/L; K 139.64, 134.85, 114.19, 131.65, 130.57 and 116.60 mg/L; Cu 0.52, 0.73, 0.41, 0.59, 0.60 and 0,73 mg/L; Fe 2,52; 3,44; 2,21; 3,08; 3,00 and 2,89 mg/L; Se 1.19, 1.87, 0.19, 0.44, 0.40 and 0.51 mg/L and Zn 1.19, 1.87, 1.38, 1.13,1.28 and 1.37 mg/L. In the serum, Ca, P, Mg, Zn, Fe and Se levels were considered appropriate for beef cattle. There was correlation between the hepatic and serum levels of Cu...(Complete abstract, click electronic address below) / Mestre

A maioria dos bovinos criados sob condições brasileiras normalmente sofre alguma restrição alimentar, que exerce efeitos negativos sobre o sistema de produção, implicando em perdas econômicas e de qualidade. Com o objetivo de reduzir esses problemas o confinamento de bovinos com dietas com alta percentagem de grãos é uma alternativa. No entanto, especialmente em relação a raça Nelore, maioria do rebanho brasileiro, a resposta a dietas com alta percentagem de grãos (amido) apresenta resultados variados. Diferentes formas de processamento dos grãos, bem como o aumento da densidade energética da dieta através da adição de gordura também têm sido estudadas. O objetivo deste trabalho foi avaliar o efeito do fornecimento de dietas contendo milho grão seco, milho grão úmido e sais de cálcio de ácidos graxos (SCAG) sobre o desempenho características de carcaça e perfil de ácidos graxos do músculo Longissimus dorsi de novilhos Nelore em fase de terminação, bem como utilizar medidas de ultra-sonografia para estimar rendimento da porção comestível após o abate. O fornecimento de milho grão úmido não alterou o ganho médio diário, reduziu a ingestão de matéria seca e tendeu a diminuir a conversão alimentar. A concentração de ácidos graxos polinsaturados, a relação polinsaturado:saturado, ácidos graxos n-6 e a relação n-6:n-3 foi maior nos animais que receberam as dietas contendo milho úmido. Os SCAG não influenciaram o ganho médio diário, aumentaram a ingestão de alimento, sem efeito sobre a conversão alimentar. Os SCAG aumentaram a percentagem de ácidos graxos n-6, bem como a relação n-6:n-3. As equações para estimativa do peso dos cortes comerciais utilizando medidas de ultra-som apresentaram acurácia semelhante àquelas utilizando as medidas obtidas diretamente na carcaça após o abate / The majority of the beef cattle raised under Brazilian conditions is periodically submitted to feed restrictions, which have negative effects to the production system, causing economic and qualitative losses. Feedlot finishing beef cattle is one alternative to avoid these losses. However, the Brazilian herd is composed mostly of cattle from the Nellore breed, which frequently do not have a good performance with diets with a high proportion of grains (starch). Several grain processing ways or increasing energy density through the inclusion of fat have been studied to improve animal performance. The aim of this study was to evaluate the effect of diets with dry corn grain, high moisture corn grain and calcium salts of fatty acids (SCAG) on the performance, carcass characteristics and fatty acids profile of the Longissimus dorsi muscle of feed lot finished Nellore steers, as well as to utilize ultrasound measurements to evaluate the edible portion after slaughter. Feeding high moisture corn had no effect on weight gain, but decreased dry matter intake and showed a tendency to decrease feed conversion. High moisture corn diets increased polyunsaturated fatty acids and the ratio of polyunsaturated to saturated fatty acids and also had greater proportion o n-6 and n-6 to n-3 ratio. Feeding SCAG did not affect average daily gain, increased feed intake without effect on feed conversion. The SCAG increased n-6 percentage and the n6 to n3 ratio. The equations to estimate the weight of the retail products using ultrasound measurements showed accuracy similar to those equations using measurements obtained in the carcass after slaughter

A maioria dos bovinos criados sob condições brasileiras normalmente sofre alguma restrição alimentar, que exerce efeitos negativos sobre o sistema de produção, implicando em perdas econômicas e de qualidade. Com o objetivo de reduzir esses problemas o confinamento de bovinos com dietas com alta percentagem de grãos é uma alternativa. No entanto, especialmente em relação a raça Nelore, maioria do rebanho brasileiro, a resposta a dietas com alta percentagem de grãos (amido) apresenta resultados variados. Diferentes formas de processamento dos grãos, bem como o aumento da densidade energética da dieta através da adição de gordura também têm sido estudadas. O objetivo deste trabalho foi avaliar o efeito do fornecimento de dietas contendo milho grão seco, milho grão úmido e sais de cálcio de ácidos graxos (SCAG) sobre o desempenho características de carcaça e perfil de ácidos graxos do músculo Longissimus dorsi de novilhos Nelore em fase de terminação, bem como utilizar medidas de ultra-sonografia para estimar rendimento da porção comestível após o abate. O fornecimento de milho grão úmido não alterou o ganho médio diário, reduziu a ingestão de matéria seca e tendeu a diminuir a conversão alimentar. A concentração de ácidos graxos polinsaturados, a relação polinsaturado:saturado, ácidos graxos n-6 e a relação n-6:n-3 foi maior nos animais que receberam as dietas contendo milho úmido. Os SCAG não influenciaram o ganho médio diário, aumentaram a ingestão de alimento, sem efeito sobre a conversão alimentar. Os SCAG aumentaram a percentagem de ácidos graxos n-6, bem como a relação n-6:n-3. As equações para estimativa do peso dos cortes comerciais utilizando medidas de ultra-som apresentaram acurácia semelhante àquelas utilizando as medidas obtidas diretamente na carcaça após o abate / The majority of the beef cattle raised under Brazilian conditions is periodically submitted to feed restrictions, which have negative effects to the production system, causing economic and qualitative losses. Feedlot finishing beef cattle is one alternative to avoid these losses. However, the Brazilian herd is composed mostly of cattle from the Nellore breed, which frequently do not have a good performance with diets with a high proportion of grains (starch). Several grain processing ways or increasing energy density through the inclusion of fat have been studied to improve animal performance. The aim of this study was to evaluate the effect of diets with dry corn grain, high moisture corn grain and calcium salts of fatty acids (SCAG) on the performance, carcass characteristics and fatty acids profile of the Longissimus dorsi muscle of feed lot finished Nellore steers, as well as to utilize ultrasound measurements to evaluate the edible portion after slaughter. Feeding high moisture corn had no effect on weight gain, but decreased dry matter intake and showed a tendency to decrease feed conversion. High moisture corn diets increased polyunsaturated fatty acids and the ratio of polyunsaturated to saturated fatty acids and also had greater proportion o n-6 and n-6 to n-3 ratio. Feeding SCAG did not affect average daily gain, increased feed intake without effect on feed conversion. The SCAG increased n-6 percentage and the n6 to n3 ratio. The equations to estimate the weight of the retail products using ultrasound measurements showed accuracy similar to those equations using measurements obtained in the carcass after slaughter

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of requirements for the degree of Master of Science. Johannesburg, 1991. / The contribution of browse and grass to the diets of cattle and goats was assessed in relation to the total biomass of woody foliage and grass available in the study area. Livestock made less use of browse during the dry season than was shown by studies conducted in the Sahel and Nylsvley, northern Transvaal. Goats fed more selectively, utilised newly flushed foliage more and fed upon a greater variety of woody plant species than did cattle. Browse contribute nore to goat diets than to cattle diets although goats were less often supplied with browse. For goats, feeding on standing browse, 'supplied browse and leaf litter occupied 34.7 % of observation time before the tree/shrub flush and 8.3 % post-flush; for cattle the contributions were 14.7 % and 5.8 %, respectively. Fruits, flowers and bark were utilised only during the pre-flush period and only by goats. Goats spent significantly more time grazing and more time browsing than did cattle during the post-flush period. Agave sisalana (sisal) contributed to cattle diets during the preflush and post-flush periods, and to goat diets during the pre-flush period. Since relatively little standing woody foliage is accessible to the animals (16.6 % preflush and 30.7 % post-flush of the wet season maximum), lopping of woody foliage by herders substantially increases the amount of food accessible to livestock, and supplied browse was eaten wherever it was encountered. Aerial cover of grass averaged less than 20 %, grass biomass ,less than 120 kgDM.ha·t and biomass concentration of grass less than 553.5 gDM.m"3 for catena toplands, catena bottomlands and drainage line thickets. The low contribution of browse to livestock diets during this study was due to the scarcity of accessible, palatable forage, exacerbated by the late flush 011 woody plants. In addition, local people harvesting live wood for fuel may compete with foraging livestock. To increase the supply of food for livestock further the rollowing practices could be encouraged: storage of woody foliage litter until the late dry season, use of chemicals to increase the nutritional value of poor quality browse and establishment of woodlots of palatable, perhaps leguminous, evergreen woody species for use as livestock fodder. / GR2017

In KwaZulu-Natal the production of beef in summer from veld is a common enterprise. Many techniques are available to optimise the productivity of this enterprise, from improving the quality of the grazing resource (planted pastures) to improving the diet of animals using nutritional supplements. To gain an insight into the production potential and financial returns possible from such improvements a trial was established at the Ukulinga Research Farm during two consecutive summer growing seasons (1997-1998 and 1998-1999). The aim was to determine the optimum beef production system for the area from both veld and kikuyu pastures. To evaluate the benefits of supplying supplementary nutrition, four alternate feed supplements, namely: 1) a Standard commercially available molasses-based protein/mineral/energy supplement; 2) a Brewers grain based protein/mineral/energy supplement, and two supplements consisting of the Brewers grain ration with either; 3) Avoparcin (an additive that improves dietary energy) or 4) Bentonite (an additive that increases the bypass of protein) were compared. As stocking rate has been shown to influence the quality of the diet consumed, the kikuyu pasture was grazed at both the recommended (1.92 LSD ha¯¹) and half the recommended stocking rate for the region. In addition, a commercial hormonal implant was applied to half of the cattle in each treatment. Grazing was monitored using the falling plate disc meter to measure pasture bulk density and laboratory analyses of herbage grab samples for digestibility and crude protein percentage. Cattle were weighed on a weekly basis and their condition was scored prior to slaughter. All enterprise costs and returns were recorded to facilitate financial analyses of the five treatments. Low rainfall and high midsummer temperatures had a detrimental effect on the productivity of the grazing and hence it was difficult to optimise production in either season. In the first season, a midsummer drought decreased the quality and quantity of both veld and kikuyu, limiting mass gain during the latter part of the season. A delay in the onset of rain at the start of the second season limited the available grazing season to 121 days as opposed to 154 days, though fodder production during the season was not limited. Trends in herbage production (quality and quantity) from veld showed moderate quality (Crude protein 7.02%; digestibility 50.2%) with an average available herbage of 1670 kg DM ha¯¹. As anticipated, kikuyu had higher quality (Crude protein 10.84%; digestibility 53.5%) and available herbage (2730 kg DM ha¯¹). These results were similar to regional benchmarks. The variable rainfall highlighted both the drought tolerance of veld and the minimum water requirements of kikuyu pastures. Lighter stocking rates tended to reduce the negative impact of moisture stress on Kikuyu pastures. The best method of producing beef (averaged over two seasons) was from heavily stocked Kikuyu pastures using the Standard supplement (1107.63 kg livemass ha¯¹). Cattle grazing veld and utilising the Avoparcin supplement produced beef at a rate of 95.96 kg ha¯¹. In comparison, the unsupplemented cattle grazing Kikuyu produced 834.87 kg ha¯¹, whilst veld grazing produced 64.43 kg ha¯¹. Hormonal implants significantly (P≤0.05) improved beef production from all sources of grazing. A lack of rain limited grazing time, causing all the cattle to be marketed whilst too lean - this negatively affected live mass gain and, hence, net financial. Although improved biological production is desirable, it is important to ensure that these gains are financially sustainable. Within the trial environment, implanted cattle fed the Standard supplement and grazing Kikuyu pastures at a high stocking rate provided the highest average gross margin of R 859.59 ha¯¹. Changing to this production system from unsupplemented veld improved expected profit by R 632.58 ha¯¹ (averaged over both seasons). Further financial analyses indicated that beef purchase price had the greatest influence on the added profit from switching from the control treatment. From a scientific standpoint these data are conclusive but it is important to remember that consumer pressure and concerns can often limit the introduction of production improvements. Such is the case with both hormonal implants and antibiotic feed additives (Avoparcin) although considering the impact of such limitations is speculative and beyond the scope of this trial. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.