CAPES / O trabalho foi desenvolvido na Fazenda Modelo do Instituto Agronômico do Paraná (IAPAR) no município de Ponta Grossa, entre o período de Junho de 2011 a Março de 2012. Com o objetivo de avaliar os sistemas de desmame precoce e da amamentação controlada sobre o desempenho de vacas e bezerros durante o período reprodutivo, foram utilizadas 161 vacas mestiças Purunã e seus respectivos bezerros, distribuídos em três grupos: Desmame precoce (DP), foi realizado através do desmame dos bezerros com média de 75 dias de idade; o grupo Amamentação Controlada (AC), as vacas foram separadas de seus bezerros e colocadas a amamentar apenas uma vez ao dia durante o período da estação de monta; o terceiro grupo era do Desmame convencional (DC), em que as vacas mantiveram seus bezerros em aleitamento durante todo do tempo, sem alguma interferência no manejo durante todo o período de avaliação. As vacas de todos os grupos pariram em condição corporal acima de 3,3 pontos (escala de 1 a 5), não apresentando diferença na taxa de prenhez, sendo 90% para as vacas do DC; 96% para as vacas da AC e 97% para as vacas do DP. Quando em boas condições ao parto a utilização do desmame precoce e da amamentação controlada não trazem benefícios produtivos, podendo o desmame precoce provocar queda na eficiência reprodutiva do plantel de cria devido ao peso do bezerro ser 19,6% menor em relação ao desmame convencional. Os bezerros submetidos ao DP apresentaram menor (P<0,05) ganho de peso diário (0,56 kg) durante o período experimental em relação ao grupo AC e DC (0,95 kg e 0,88 kg, respectivamente) os quais não diferiram entre si (P<0,05). O manejo da amamentação controlada não provoca efeito no desempenho dos bezerros, podendo ser desmamados com peso similar aos bezerros mantidos ao pé da vaca. A categoria das vacas (Jovens, Adultas e Velhas) não apresentou interação com o sistema de desmame. Observou-se que Vacas jovens, são mais leves (P<0,05) ao parto e ao desmame de seus bezerros (383,89 e 399,40 kg, respectivamente) em relação às vacas adultas (444,07 e 451,92 kg) e velhas (452,35 e 470,49 kg). Desta forma as Novilhas acasaladas aos dois anos paridas em boas condições nutricionais apresentam a mesma eficiência reprodutiva que vacas adultas (47,64 e 48,35 kg de bezerro ao desmame/100 kg de vaca, respectivamente), ao passo que vacas velhas apresentam a menor eficiência reprodutiva no plantel de cria (42,99 kg de bezerro/100kg de vaca). O menor peso ao desmame de bezerros filhos de vacas primíparas e velhas é devido ao menor peso desde o nascimento até os 150 dias de idade, não havendo diferença no desempenho a partir deste período. / The study was developed at Fazenda Modelo an Experimental Estation belonged to the Insituto Agronômico do Paraná (IAPAR) in the city of Ponta Grossa, Pr, in the period from June 2011 to March 2012. Aiming to evaluate the systems of early weaning and controlled nursing about the performance of cows and calves during the breeding season, 161 crossbred Purunã cows and their calves were used and the were divided into three groups: Early weaning (DP), which was fulfilled weaning of calves with the average age of 75 days; the group of controlled nursing (AC), the cows were separated from their calves and placed to breastfeed only once a day during the breeding season; and the third group was the conventional weaning (DC), which the cows kept their calves together during the whole time without any interference in the management, with definitive weaning at seven months. Cows from all groups calved in body condition score above 3.7 points (scale from 1 to 5), with no significant difference in the pregnancy rate, 90% for cows in DC, 96% for cows for AC and 97% for cows of early Weaning. When in good condition at calving the use of early weaning or controlled nursing do not bring productive benefitis, early weaning can cause decline in reproductive efficiency of the breeding herd because of the weight of the calf to be 19.6% lower compared to conventional weaning. Calves subjected to the DP showed a lower overage (P <0.05) daily weight gain (0.56 kg) during the experimental period compared to the group at the AC and DC (0.95 kg and 0.88 kg, respectively) which did not differ from each other (P <0.05). The management of controlled nursing causes no effect on the performance of calves, that can be weaned with similar weight to calves maintained together the cow. As the cow category (Young, Adult and Old) showed no interaction with the system weaning, they were discussed independently. It was observed that young cows are lighter (P <0.05) at calving and weaning of their calves (383.89 and 399.40 kg, respectively) compared to mature cows (444.07 and 451.92 kg) and old (452.35 and 470.49 kg). Therefore, the Heifers bred at two years old, that calve in good nutritional conditions have the same reproductive efficiency that adult cows (47.64 and 48.35 kg of weaning calf to 100 kg/cow, respectively), while the old cows show lower reproductive efficiency in a breeding herd (42.99 kg of calf per 100kg/cow). The lower weaning weight of calves born from primiparous and old is because of the lower weight and performance since the birth to 150 days of age, with no difference in performance after this period.

Thesis (M.Sc. Agriculture (Animal Production)) -- University of Limpopo, 2022 / Refer to document / National Research Foundation (NRF)

Master of Science

An experiment was conducted using forty-one Bonsmara steers (age ± 7 months) to determine the effect of zilpaterol hydrochloride (ZH) on the growth performance and carcass characteristics. The trial was structured using a completely randomized design with two treatments, control and ZH group. The steers were fed ZH for 28 consecutive days at the end of the finishing period and ZH was withdrawn from the diet 2 days prior to slaughter of the animals. The steers were placed in individual pens and weighed fortnightly throughout the 4 months trial. Zilpaterol hydrochloride (ZH) was included in the diet at a rate of 8.3 mg/kg of DM. Feeding of ZH increased (P< 0.05) body weight (BW) gain and ADG (1.102 vs. 1.444) and tended to increase (P = 0.067) feed efficiency (F:G) during the last month of the finishing period. There were no significant differences (P> 0.05) in daily dry matter intakes (DMI). For the control group, high treatment weight gains were significantly associated with high initial weight (r = 0.424, P = 0.049) and also high pre-treatment body weight (r = 0.678, P= 0.001). Treatment weight gain increased as the initial and pre-treatment weight gain increased in the control group. For the steers that were fed ZH, there was no significant correlation between the treatment body weight gain with initial weight (r = 0.097, P = 0.694) and also pre- treatment live weight (r = 0.393, P = 0.096). Supplementation of ZH significantly increased (P < 0.0001) the dressing percentage (56.4% vs. 58.4%) and had no significant (P>0.05) effect on the carcass weight. The outcome of the study suggest that supplementation of ZH in the diet during the last month of the finishing period enhances growth performance and shows the repartitioning capacity of the feed additive as a beta- agonist. / Agriculture and  Animal Health / M. Sc. (Agriculture (Animal Science)

Call number: LD2668 .T4 1986 N44 / Master of Science / Agricultural Economics

There is growing public concern about the high proportion of saturated fatty acids in milk fat; however, feed intake, energy partitioning toward milk synthesis, and milk fat concentrations can decrease when cows are fed high concentrations of unsaturated lipids. The objective of this study was to identify the optimal rate for feeding OmegaBoostTM (a flaxseed supplement that was processed using a proprietary technique by Double Pass LLC, Tualatin, OR) to dairy cows. The central hypothesis was that supplementation with OmegaBoost will decrease the proportion of saturated fatty acids in milk fat in a dose dependent manner. Using a latin-square design, 10 Holstein cows in mid to late lactation were fed for two-week periods 0, 2, 4, or 6 lbs/d of OmegaBoost or 4lbs/d ground flax as top dressing to their total mixed ration. Feed intake, body weight, activity and resting time, milk production and milk composition were measured daily. At the end of each two-week period, milk and serum samples were taken and analyzed for fatty acid composition using gas chromatography. In addition, fresh Mozzarella cheese and butter was manufactured and tested to determine the fatty acid composition and the effects of flaxseed supplementation on texture. Feeding OmegaBoost at 2, 4, and 6 lbs/d linearly decreased the proportion of saturated fatty acids in milk by 6, 15, and 18%, respectively, and linearly increased the proportion of mono-unsaturated fatty acids (14, 32, and 35%), poly-unsaturated fatty acids (16, 49, and 82%), and α-linolenic acid (26, 52, and 70%). Similar changes in fatty acid composition were observed in butter and cheese samples, resulting in butter that was less hard and adhesive at refrigeration temperature in response to feeding cows increasing concentrations of OmegaBoost. Feed intake, body weight, serum metabolite concentrations, milk production and composition, and butter and cheese yield were not significantly affected by feeding processed flaxseed. Therefore, feeding 4 or 6 lbs/d of OmegaBoost to dairy cows is effective in improving the nutritional and textural profile of dairy products without negatively affecting feed intake, milk production, or weight gain. / Graduation date: 2012

South African dairy farmers have generally used kikuyu pasture to tide them over from one ryegrass season to the next, and as a result of its resilient nature, have assumed careful management of it to be unnecessary. This has resulted in its mismanagement which is unaffordable in current times where the profitability of dairy farming is increasingly dependent on low input, pasture-based systems. Kikuyu pasture may play a larger role in supplying nutrients to dairy cattle over the summer months in future as the alternative home produced feed sources such as silage and perennial ryegrass become increasingly unaffordable. Improving animal production from kikuyu is difficult as there is little information relating kikuyu pasture management to dairy cow performance. Efficient utilization and quality of temperate pasture have been more comprehensibly researched. The relations discovered between the chemical compounds in temperate grass species have been applied to tropical pastures such as kikuyu with limited success and often confusing results. For example, crude fibre in kikuyu was found to be positively related to digestibility. In South Africa, much research has been done on the use of kikuyu in beef production systems. This information has been applied to dairy farming systems with limited success, owing to the higher metabolic demands of dairy animals. Pasture farming needs to become more precise to improve pasture quality and hence milk yields as research trials focussing on stocking rate and grazing system comparisons have yielded results that are too general with little application at the farming level. A need for integrated and flexible management of animals and pastures has been recognised. The grazing interval is a key aspect in improving pasture and animal performance and fixed rotation lengths and stocking rates have been identified as being detrimental to performance. The relation between growth stage and pasture quality has lead researchers to identify plant growth characteristics, such as pasture height and leaf stage, as signs of grazing readiness. At the four and a half leaves per tiller stage of regrowth, the chemical composition ofthe kikuyu plant is more in line with the requirements ofthe dairy cow, with the leaf to stem ratio at its highest. The primary limitation of kikuyu pasture is a lack of energy, particularly readily fermentable carbohydrate, which makes the fermentation of structural carbohydrates difficult and dry matter intakes are reduced. Other limitations to animal performance include high cell wall constituents, low calcium, magnesium and sodium content and antinutritional factors such as nitrate and insoluble oxalate. These deficiencies and antinutritional factors are in some cases unique to 5 kikuyu pasture, meaning that kikuyu specific supplementation may be the key to improving performance from dairy cattle grazing kikuyu pasture. The objectives are to evaluate current kikuyu management systems in South Africa and their impact on dairy cow performance and to evaluate the use of pasture height and burning as quality control tools. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

Long-term trends in rangeland sward dynamics (species composition, structure, productivity) were examined on three trials established between 1989 and 1996 at Kokstad Research Station in the Highland Sourveld, while animal performance (average daily gain and gain per hectare) was examined on two of the trials. The region enjoys moderate rainfall of 782mm per annum, with hilly topography, and soil depths ranging from >1m to <20cm. The first trial was labelled the simulation trial, as it simulated a four-paddock rotational grazing system, in which animals spent two weeks in each of three paddocks while the fourth was rested for the entire season. The rested paddock was rotated each year. The trial tested two stocking rates (0.5 and 1.0 AU.ha-1) at five ratios of cattle to sheep, ranging from cattle only to sheep only. The trial was unreplicated, and was established in 1989 on flat topography with deep soils. The second trial (labelled the flat two-paddock trial) was established in 1992 adjacent to the simulation trial. The trial examined two stocking rates of sheep weaners (0.5 and 1.0 AU.ha-1 seasonally) in a continuous grazing two-paddock system, in which one paddock of each treatment was burned and grazed continuously while the second paddock was rested, to be burned and grazed in the following season. The trial was replicated twice. The third trial (labelled the steep two-paddock trial) mimicked the grazing system of the flat trial, but was located on a steep (c. 20%) West-facing slope with shallow soils. The trial incorporated two additional treatments: an intermediate stocking rate of 0.7 AU.ha-1 and an ungrazed treatment. Species composition of the sward was recorded biennially on all trials using the nearest plant-point technique with between 200 and 800 points per paddock. Sward standing crop was measured in the rested seasons of the simulation trial and at the beginning, middle and end of each season in one paddock of each two-paddock treatment of the two-paddock trials. In the two-paddock trials, sward standing crop was measured within and outside permanently placed exclosure cages. Animals were weighed fortnightly. The response of species to grazing pressure or animal type was mediated by soil depth and slope, as well as the grazing system. Tristachya leucothrix declined on all grazed treatments. The ungrazed treatments remained relatively stable over ten years. On the low stocking rate treatments of the steep trial, unpalatable species increased, but so did Themeda triandra. The heavily grazed treatment of the steep trial was surprisingly stable, with little significant change in relative abundance of key species other than an increase in the unpalatable Alloteropsis semialata and decline in T. leucothrix. The medium stocking rate treatment on the steep trial showed significant shifts in relative abundance of key species, with declines in T. triandra and T. leucothrix and increases in A. semialata and the unpalatable wiregrass D. filifolius. These trends were not repeated on the flat trial, however, with T. triandra and A. semialata increasing and all other key species declining or remaining stable. On the simulation trial, species responded largely unpredictably with species abundances often fluctuating considerably over time. Microchloa caffra and A. semialata increased substantially in both the low and high stocking rate sheep-only treatments, with a concurrent decline in T. triandra in the high stocking rate but not the low. Changes in composition over time, as measured by Euclidean distance, showed that shallow soils, high stocking rates and a high proportion of sheep caused greater shifts in species composition over time than deep soils, low stocking rates or more cattle. Three treatments, the sheep-only treatments on the simulation trial and the high stocking rate on the steep trial, showed an initial rapid shift in composition over about 6 years, before stabilising in subsequent seasons. The flat trial showed no substantial shift in composition over time. This general pattern of change was confirmed by Non-Metric Multidimensional Scaling. On the simulation trial, total standing crop was influenced by stocking rate and by the proportion of sheep in most seasons. On the two-paddock trials, increasing stocking rate significantly reduced sward vigour, and vigour declined over time. Stocking rate reduced total standing crop on both trials at the end of the 2004/05 seasons and the crop of unpalatable species on the steep trial. Total palatable plants were unaffected by stocking rate on both trials. The classic Jones-Sandland model of animal performance as influenced solely by stocking rate was not supported. Sheep performance was influenced by stocking rate and the interaction of stocking rate and seasonal rainfall. There was no difference in average daily gain between treatments over time, and hence cumulative animal production per hectare increased with increasing stocking rate. Animal performance was possibly influenced by many factors beyond the scope of this study, including the effect of predator attacks on surviving animals, and resource availability such as shade and shelter and high-production patches in some paddocks and not others. Scale effects on ecology are being increasingly investigated and a meta-analysis of this type shows that, even in one research farm, slight differences in management and environment can have significant effects on plant and animal responses to grazing. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

An experiment was conducted using forty-one Bonsmara steers (age ± 7 months) to determine the effect of zilpaterol hydrochloride (ZH) on the growth performance and carcass characteristics. The trial was structured using a completely randomized design with two treatments, control and ZH group. The steers were fed ZH for 28 consecutive days at the end of the finishing period and ZH was withdrawn from the diet 2 days prior to slaughter of the animals. The steers were placed in individual pens and weighed fortnightly throughout the 4 months trial. Zilpaterol hydrochloride (ZH) was included in the diet at a rate of 8.3 mg/kg of DM. Feeding of ZH increased (P< 0.05) body weight (BW) gain and ADG (1.102 vs. 1.444) and tended to increase (P = 0.067) feed efficiency (F:G) during the last month of the finishing period. There were no significant differences (P> 0.05) in daily dry matter intakes (DMI). For the control group, high treatment weight gains were significantly associated with high initial weight (r = 0.424, P = 0.049) and also high pre-treatment body weight (r = 0.678, P= 0.001). Treatment weight gain increased as the initial and pre-treatment weight gain increased in the control group. For the steers that were fed ZH, there was no significant correlation between the treatment body weight gain with initial weight (r = 0.097, P = 0.694) and also pre- treatment live weight (r = 0.393, P = 0.096). Supplementation of ZH significantly increased (P < 0.0001) the dressing percentage (56.4% vs. 58.4%) and had no significant (P>0.05) effect on the carcass weight. The outcome of the study suggest that supplementation of ZH in the diet during the last month of the finishing period enhances growth performance and shows the repartitioning capacity of the feed additive as a beta- agonist. / Agriculture and  Animal Health / M. Sc. (Agriculture (Animal Science)

Made available in DSpace on 2015-03-26T13:55:24Z (GMT). No. of bitstreams: 1 texto completo.pdf: 614632 bytes, checksum: eac726a0efd1eec87578c9745a474e81 (MD5) Previous issue date: 2014-02-26 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work aimed to evaluate the effects of ruminal and/or abomasal protein supplementation in cattle fed tropical forages on nutritional variables, degradation of insoluble fiber, activity of fibrolytic enzymes and rumen bacterial communities profile. Two experiments were carried out sequentially, and in the same way, differing only on the forage quality that was defined based on crude protein content: medium quality (784 g of crude protein/ kg of dry matter) and high quality (986 g of crude protein/ kg of dry matter). Four Nellore young bulls, averaging 227±11 kg body weight and fitted with ruminal and abomasal cannullas, were used. The following treatments were evaluated: control (only forage), ruminal nitrogenous compounds supplementation (daily supply of 230 g of crude protein in the rumen), abomasal nitrogenous compounds supplementation (daily supply of 230 g of crude protein in the abomasum), and ruminal and abomasal nitrogenous compounds supplementation (daily supply of 230 g of protein, being 115 g in the rumen and 115 g in the abomasum). Casein was used as protein source for supplementation and basal diet consisted of Tifton 85 (Cynodon spp) hay. Two 4 x 4 Latin squares experimental trials, balanced for residual effects, with four treatments, four animals and four experimental periods lasting 29 days each, were implemented sequentially, one for each forage as stated above. There were no effects (P>0.05) of supplementation scheme or forage quality on organic matter (OM) intake. On the other hand, neutral detergent fiber (NDF) intake was higher (P<0.05) when animals were fed high quality forage. The total digestibility of OM was increased (P<0.05) by supplementation and by increasing forage quality. The digestibility coefficient of NDF was not affected by supplementation scheme (P>0.05), but was increased by the enhancing in forage quality. The apparent ruminal nitrogen balance (RNB) was increased (P<0.05) when animals were supplemented in rumen or in both rumen and abomasum cannula. It is worth highlighting that no supplementation or exclusively abomasal supplementation led to negative values of RNB. The apparent nitrogen balance (NB) was increased (P>0.05) when high quality forage was fed to the animals and by supplementation, no matter if the supplement was infused into rumen, abomasum or both. Ruminal supplementation enhanced (P<0.05) the concentration of rumen ammonia nitrogen (RAN). Although, animals supplemented in rumen and abomasum or exclusively in abomasum did not exhibit increase in RAN concentrations (P>0.05) when compared to no supplemented animals. The bacterial richness and diversity (Shannon-Wiener index) associated with the solid phase of rumen digesta were not affected (P>0.05). However, richness and diversity associated with the liquid phase were increased (P<0.05) by the improvement in forage quality. NDF degradation rate (kp) was enhanced (P<0.05) by ruminal supplementation. Carboximetilcellulase activity was decreased (P<0.05) by the abomasal and ruminal/abomasal supplementation. Xylanase activity was decreased (P<0.05) by both post-ruminal supplementation schemes, when high quality forage was fed to the animals. It was not detected correlations among variables associated with bacterial diversity and activity and variables associated with nutritional performance, excepted for the positive correlation between kp and RNB Clustering analyses based on the Unweighted Pair Group Method (UPGMA) evidenced that distinct bacterial communities are associated with liquid and solid fraction, independently of the forage quality. Clustering analyses also showed that forage quality affects the diversity of liquid phase associated bacteria, even though, effects on solid phase was not clear. None of the evaluations related to the microbial community were able to detect clear effects of supplementation on the microbial community diversity. Improving forage quality enhances fiber digestibility, nitrogen balance and modifies the bacterial community associated with liquid phase. On the other hand, protein supplementation enhances the nitrogen retention in animal body. / Objetivou-se avaliar os efeitos da suplementação proteica ruminal e/ou abomasal em bovinos consumindo forragens tropicais sobre as características nutricionais, a atividade enzimática fibrolítica, a degradação in vitro da fibra insolúvel e o perfil da comunidade bacteriana ruminal. Dois experimentos foram realizados sequencialmente diferindo apenas na qualidade do feno ofertado, sendo de média qualidade (78,4 g de proteína bruta/kg de matéria seca) e alta qualidade (98,6 g de proteína bruta/kg de matéria seca), respectivamente. Os procedimentos experimentais foram os mesmos para ambas as forragens. Foram utilizados quatro novilhos Nelore, não castrados, com peso corporal médio de 227±11 kg, fistulados no rúmen e no abomaso. Foram avaliados os seguintes esquemas de suplementação: controle (somente forragem); suplementação nitrogenada ruminal (fornecimento diário de 230 g de proteína suplementar no rúmen); suplementação nitrogenada abomasal (fornecimento diário de 230 g de proteína suplementar no abomaso) e suplementação nitrogenada ruminal e abomasal (fornecimento diário de 230 g de proteína suplementar, sendo 115 g no rúmen e 115 g no abomaso). A alimentação volumosa basal foi constituída por feno de tifton 85 (Cynodon spp) e como fonte de compostos nitrogenados suplementares foi utilizada a caseína (caseína pura, Labsynth). O experimento foi conduzido segundo delineamento em quadrado latino 4 x 4 balanceado para efeitos residuais, sendo dois quadrados sequenciais, um para cada forragem, com quatro esquemas de suplementação, quatro animais e quatro períodos experimentais com 29 dias em cada quadrado. Não foram observados efeitos (P>0,05) da qualidade da foragem ou do esquema de suplementação sobre o consumo de matéria orgânica (MO). Por outro lado, o consumo de fibra em detergente neutro (FDN) foi superior (P<0,05) quando forragem de alta qualidade foi ofertada aos animais. O coeficiente de digestibilidade total da MO foi incrementado (P>0,05) pela suplementação e pela melhoria na qualidade da forragem. O coeficiente de digestibilidade da FDN não foi afetado pelo esquema de suplementação (P>0,05), mas foi superior quando os animais receberam forragem de alta qualidade (P<0,05). O balanço aparente de compostos nitrogenados no rúmen (BNR) foi ampliado (P<0,05) pela suplementação no rúmen e no rúmen-abomaso. Ressalta-se que a ausência de suplementação ou a suplementação exclusiva no abomaso proporcionam valores negativos de BNR. O balaço aparente de compostos nitrogenados no organismo animal foi ampliado (P<0,05) pelo fornecimento de suplemento, independentemente do local de suplementação, e pelo fornecimento de forragem de melhor qualidade A suplementação no rúmen incrementou (P<0,05) a concentração de nitrogênio amoniacal ruminal (NAR). Por outro lado, animais recebendo suplementação no rúmen e abomaso ou exclusivamente no abomaso apresentaram concentrações de NAR similares (P>0,05) a animais não suplementados. A riqueza e a diversidade microbiana da fase sólida da digesta ruminal não foram afetadas (P>0,05). Entretanto, a riqueza e a diversidade bacteriana associada à fase líquida da digesta ruminal foram incrementadas (P<0,05) pela melhoria na qualidade da forragem. A taxa de degradação da FDN foi ampliada (P<0,05) pela suplementação no rúmen. A atividade da carboximetilcelulase foi reduzida (P<0,05) pela suplementação no abomaso e rúmen-abomaso. A atividade da xilanase foi deprimida (P<0,05) pela suplementação pós-ruminal somente quando forragem de alta qualidade foi fornecida aos animais. Não foi observada correlação (P>0,05) entre as variáveis associadas à atividade enzimática e diversidade microbiana e as características ligadas ao desempenho nutricional, exceção feita à correlação positiva (P<0,05) entre a taxa de degradação da FDN e o BNR. A avaliação multivariada da diversidade permitiu evidenciar que comunidades bacterianas distintas estão associadas às frações líquida e sólida, independente da qualidade da forragem ofertada. Percebeu- se que a variação na qualidade da forragem influencia a diversidade microbiana associada à fração líquida do fluido ruminal, embora não tenha exercido tal efeito sobre a fração sólida. Em nenhuma avaliação percebeu-se efeito claro do esquema de suplementação sobre o perfil da comunidade microbiana ruminal. A melhoria da qualidade da forragem amplia a digestibilidade da fibrae a retenção de nitrogênio e é capaz de modificar a comunidade bacteriana associada à fração liquida do conteúdo ruminal. A suplementação proteica, por sua vez, independentemente do local de suplementação, amplia a retenção de nitrogênio no organismo animal.