• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 200
  • 101
  • 34
  • 25
  • 25
  • 25
  • 25
  • 25
  • 25
  • 12
  • 2
  • 1
  • Tagged with
  • 435
  • 435
  • 435
  • 158
  • 123
  • 94
  • 76
  • 73
  • 72
  • 60
  • 55
  • 48
  • 48
  • 40
  • 35
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
241

Effects of a propionic acid-based additive on short-term ensiling characteristics of corn and on dairy cows performance

Levital, Tamir. January 2006 (has links)
Forage shortage may force producers to feed unfermented or partially fermented forages, which are more susceptible to aerobic deterioration. Propionic acid-based additives can be added to ensiled forages to inhibit yeast and mold growth, and improve the aerobic stability of silages. The objectives of this study were to determine the effects of a propionic acid-based silage additive (Solution Foin) on ensiling characteristics, aerobic stability and feeding value of short-term ensiled corn forage. Chopped whole corn was left untreated or treated with Solution Foin (contains 700 g kg-1 propionic acid and 300 g kg-1 NH4OH). The additive was added to forage prior ensiling at a rate of 5 L ton-1 (wet basis). Treated and untreated forages were placed in six plastic silo bags (three each). Silo bags were opened one day after ensiling and daily samples were collected for 30 consecutive days. Effects on animal performance of feeding treated or untreated forage were determined in a completely randomized design, using 30 lactating cows (178+/-55 days in milk) fed total mixed ration (50:50 forage: concentrate) with the major forage portion consisting of untreated or treated forage. The feeding study started one day post-ensiling. Results showed that Solution Foin reduced (P < 0.05) yeast and mold populations between d 5 and 14 post-ensiling. The highest differences (P < 0.002) were observed on d 10, at which point yeast and mold populations for untreated silage were 7.86 and 2.51 log cfu g-1, respectively. The corresponding values for treated silage were 4.35 and 0.00 log cfu g-1, respectively. Aerobic stability of treated ensiled forage was also improved (P < 0.01) from day 0 (by 159 h) to day 10 (by 33 h) post-ensiling. Solution Foin also increased (P < 0.05) the overall lactic acid and WSC content, and lowered the temperature of the treated ensiled forage in the field. No treatment differences were detected in the forage pH and acetic acid concentration. Dairy cows fed treated forage had similar feed intake (average 23 kg d-1) and milk yield (average 29 kg d-1) to cows fed the untreated forage. It was concluded that Solution Foin can be used to improve the aerobic stability and ensiled forage characteristics of short-term corn forage, likely by reducing yeast and mold populations.
242

Fish meal supplementation of high quality grass silage in dairy cows

Pomerleau, Yvan N. January 1997 (has links)
The aim of this study was to maximize good quality grass silage utilization either by supplying a source of rumen undegradable protein or by a reduction of the concentrate in the diet. A randomized incomplete block design was used to evaluate feed intake, milk production and health incidence occurring in fifty-nine Holstein dairy cow (11 primiparous) distributed randomly to receive three different diets between wk 4 and 24 of lactation. The diets were composed of grass silage (predominance of timothy) offered ad libitum supplemented either with a mixture of cereal grains (wheat:barley 50:50) at 100% of recommendations plus soybean meal (Trt 1), or fish meal (Trt 2), or with cereal grains at 75% of recommendations plus fish meal (Trt 3). The grass silage was harvested at an approximate chop length of 8--10 cm, averaged 37.1% DM and was stored in heap silos. / Finally, an economic evaluation of the treatments was done using milk income, feed cost, health cost, and net income. (Abstract shortened by UMI.)
243

Effect of source of nonstructural carbohydrates on performance of dairy cows fed sunflower seeds

Abdelqader, Malek January 2005 (has links)
Three studies were conducted to determine the effects of nonstructural carbohydrate (NSC) sources on performance of dairy cows fed sunflower seeds. In the first study, the effects of NSC source on dry matter (DM) intake, milk yield and milk fatty acid composition were evaluated using fifteen lactating Holstein cows in a 3 x 3 Latin square design. In the second study, fifteen lactating Holstein cows were used in a completely randomized design to determine the effects of NSC on the total tract nutrient utilization. The third study was designed to determine in situ ruminal degradability of DM, CP, NDF and starch of dietary treatments of study one and two, where two ruminally fistulated cows used in a randomized complete block design. Results of the in situ ruminal degradability trial showed that BC and CBC had similar effective ruminal degradability of DM and CP which was higher (P < 0.05) than that of CC. However, starch ruminal degradability was highest for BC, intermediate for CBC and lowest for CC. Sources of NSC had no effect on the NDF in situ ruminal degradability. It was concluded that changing the source of NSC and feeding sunflower seeds can modify milk fatty acid composition without any adverse effect on milk yield or milk components, and with no detrimental effect on nutrients utilization. (Abstract shortened by UMI.)
244

Fate of B-complex vitamins in the gastrointestinal tract of dairy cows

Santschi, Debora January 2004 (has links)
Three experiments were conducted to characterize the fate of B-vitamins in the gastrointestinal tract of dairy cows. Experiment 1 was undertaken to verify if differences among published studies could be explained by methods of collection and preparation of ruminal fluid, using four ruminally cannulated non-lactating Holstein cows. Acidification of fresh ruminal fluid, causing the lysis of bacterial cells, yielded higher B-vitamin concentrations than differential centrifugation, while the method of collection used did not have an important impact. Results suggested that most of the vitamins are present in the bacterial fractions, and that only limited amounts are present in the surrounding fluid. Experiment 2 looked at the vitamin concentrations in ruminal bacterial fractions and particle-free fluid as influenced by diet composition. Six lactating ruminally cannulated Holstein cows were used in a cross-over design, and the diets were formulated to have forage to concentrate ratios of 60:40 (high-forage) and 40:60 (low-forage). B-vitamins were present mainly in the bacterial fractions of the rumen, with greater effects of the forage to concentrate ratio on vitamin concentrations in the bacteria associated to the solid fraction than on those present in the liquid portion of the rumen. These results strongly suggested that ruminal B-vitamin synthesis is influenced by the forage to concentrate ratio. Experiment 3 investigated the fate of supplementary B-vitamins, using four cows equipped with cannulae in the rumen, the proximal duodenum and the distal ileum. Extensive losses of dietary supplements appeared prior to the duodenum for all vitamins, but intestinal disappearance rates of most vitamins were increased by supplementation.
245

Utilization of tropical pasture by beef cattle : the Cornell Net Carbohydrate and Protein System (CNCPS) and in situ mineral release in the rumen

Buck, Kevin January 2007 (has links)
Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 61-66). / vii, 66 leaves, bound ill. 29 cm
246

Frequências de alimentação sobre o comportamento ingestivo, digestibilidade do amido e flutuação de consumo em bovinos Nelore confinados

Silva, Juliana da [UNESP] 29 September 2014 (has links) (PDF)
Made available in DSpace on 2015-05-14T16:53:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-09-29Bitstream added on 2015-05-14T16:59:25Z : No. of bitstreams: 1 000824716.pdf: 269638 bytes, checksum: dee550a0fdd517adf36ec6b205dc2fd0 (MD5) / O objetivo do presente estudo foi avaliar as frequências de alimentação sobre o comportamento ingestivo, digestibilidade do amido e FDN e flutuação do consumo de massa seca (CMS) em bovinos Nelore confinados. Foram utilizados 48 machos não castrados com peso corporal médio inicial de (358,2±19,4kg), divididos em 4 tratamentos: 1) fornecimento da ração (1x ao dia, 8:00h), 2) (2x, 8:00h e 14:00h), 3) (3x, 8:00h, 11:00h e 17:00h) e 4) (4x, 8:00h, 11:00h, 14:00h e 17:00h), caracterizando delineamento em blocos casualizados, com 12 animais por tratamento (1animal/baia). O experimento teve duração de 94 dias, sendo 9 dias de adaptação (ADAP) com aumento do nível de concentrado de 60% para 86%. A dieta de terminação (TERM) continha: 67% de grãos de milho quebrados, 14% de bagaço de cana, 9% de casca de soja, 5,5% de farelo de soja, 4,0% de núcleo mineral com uréia, 0,5% de calcáreo. Na fase de ADAP, com o aumento da frequência de alimentação a variação do CMS, expressa em % e kg, foi afetada de forma cúbica (P = 0,05), entretanto na fase de TERM, expressa em %, não foi afetada (P > 0,10), quando expressa em kg, na fase de TERM e período total de confinamento foram afetados de forma linear e quadrática (P < 0,05). Para o comportamento ingestivo na fase de ADAP somente as variáveis CMS e Consumo de FDN foram afetados de forma quadrática (P = 0,06) e cúbica (P = 0,02), respectivamente. No entanto, na fase de TERM o CMS foi afetado de forma linear (P = 0,02), o tempo de ruminação e ócio foram afetados de forma cúbica (P < 0,01) e consumo de FDN, eficiência de alimentação e ruminação de FDN foram afetados de forma quadrática e cúbica (P < 0,01). Na fase de ADAP digestibilidade do amido foi afetada de forma linear (P = 0,03) e cúbica (P < 0,01). Contudo, na fase de TERM somente a porcentagem de amido fecal foi afetada de forma quadrática (P = 0,05). Para a seletividade dos ingredientes não houve influência da ... / The aim of this study was to evaluate feeding frequency on feeding behavior, digestibility of starch and NDF and fluctuation of dry matter intake (DMI) in confined Nellore. Were used 48 no neutered males with average initial body weight (358.2±19,4kg), divided into 4 treatments: 1) (1x; 0800h), 2) (2x; 0800h and 1400h), 3) (3x; 0800h, 1100h and 1700h) and 4) (4x; 0800h, 1100h, 1400h and 1700h), indicating delineation randomized blocks, with 12 animals per treatment (1animal / pen). The experiment lasted 94 days, and the adaptation (ADAP) lasting nine days with the increased level of 60% to 86% concentrate diet. Diet finishing (FINISH) contained: 67% broken grains of corn, 14% of sugar cane, 9% soybean hulls, 5.5% soybean meal, 4.0% mineral mixture with urea, 0.5% limestone. ADAP in phase, with increasing feeding frequency variation DMI, and expressed % in kg was affected cubically (P = 0.05), however the phase FINISH, expressed in %, was not affected (P > 0.10), when expressed in kg, during the FINISH and total period of confinement were affected linearly and quadratically (P < 0.05). For the feeding behavior in phase ADAP only the DMI and consumption of neutral detergent fiber (NDF) variables were affected quadratically (P = 0.06) and cubic (P = 0.02), respectively. However, during FINISH the DMI was affected linearly (P = 0.02), the time of ruminating and resting were affected cubically (P <0.01) and intake NDF, feed efficiency and rumination NDF were affected quadratic and cubic (P <0.01) respectively. In phase ADAP only starch digestibility was affected linearly (P = 0.03) and cubic (P <0.01). However, during the FINISH only the percentage of fecal starch was affected quadratically (P = 0.05). For the selection of ingredients in stages ADAP and FINISH there was no influence of feeding frequency. Practically, Nellore food at least three times a day seems to be the most indicaded option
247

Uso de cloridrato de zilpaterol em dietas para bovinos nelore confinados / Use of zilpaterol hydrochloride on feedlot diets of nellore cattle

Brichi, André Luis Coneglian [UNESP] 14 November 2014 (has links) (PDF)
Made available in DSpace on 2015-03-03T11:52:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-11-14Bitstream added on 2015-03-03T12:07:29Z : No. of bitstreams: 1 000809238.pdf: 499064 bytes, checksum: e1f9a48a2c6a203be664290ac0590d4a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Objetivou-se com este trabalho avaliar a inclusão de Cloridrato de Zilpaterol (CZ) na ração de bovinos Nelore quanto ao efeito no desempenho produtivo, nas características de carcaça, no comportamento ingestivo e na qualidade de carne de bovinos Nelore confinados. Foram utilizados 72 animais machos, sendo 36 castrados e 36 não castrados, com peso vivo médio inicial de 347,5 kg ± 21.61 kg, e provenientes de recria em sistema de pastejo contínuo. O delineamento experimental foi de blocos casualizados em arranjo fatorial 2 x 2 (sexo e adição de CZ), constituindo os seguintes tratamentos: castrados sem adição de CZ (C) ou com adição de CZ (CZ) e não castrados sem adição de CZ (NC) ou com adição de CZ (NCZ). Cada tratamento foi composto por 6 baias (3 animais/baia), sendo estas consideradas as unidades experimentais para este estudo. A administração de 7,5 mg/kg de MS de CZ ocorreu por 20 dias durante o período final de confinamento, respeitando a carência de três dias antes do abate. Houve efeito significavo (P < 0,01) de CZ para GPD e EA durante o período tratado. Para o mesmo período houve interação (CZ x Sexo) (P < 0,04) com redução de IMAS e IMASPV para os animais CCZ apenas. A administração de CZ durante o período total de confinamento resultou (P < 0,04) em redução na IMASPV e melhora da EA e EB. Houve incremento (P < 0,04) no PCQ, RC, PCF, e AOL para os animais alimentados com CZ. A suplementação com CZ aumentou significativamente (P < 0,05) os pesos da maioria dos cortes carneos da região do quarto traseiro. Não foi observado efeito significativo (P > 0,05) sobre a EGSF, força de cisalhamento e coloração da carne. Para a análise sensorial de carne, bovinos castrados não foram prejudicados quando suplementados com CZ. Assim sendo, a adição de CZ em dietas de terminação para bovinos Nelore castrados e não castrados, proporcionou melhora no desempenho ... / This objective was to evaluate the inclusion of Zilpaterol hydrochloride (CZ) ration on performance, carcass characteristics, feeding behavior and meat quality of feedlot Nellore. 72 male animals were used, 36 steers and bulls 36, with average weight of 347.5 kg ± 21.61 kg, and from rearing in continuous grazing. The experimental design was a randomized block in a 2 x 2 factorial arrangement of treatments (sex and ZH), as follows: steers without CZ (CC) or with CZ (CCZ), bulls without CZ (NCC) or with CZ (NCCZ). Each treatment consisted of 6 pens (3 animals/pen), which were considered the experimental units for this study. The CZ was administrated during the last 20 days of feeding (7,5 mg/kg of dry matter), allowing 3 days of withdrawl priot to slaughter. There was CZ main effect (P < 0,01) for average daily gain and feed efficiency during CZ treatment period. Morevoer, it was an interaction (Sex x CZ) (P < 0,04) where both dry matter intake in kilos (DMI) and as percentage of body weight (IMSPV) were reduced for CCZ. The administration of CZ considering the entire trial resulted (P < 0,04) in reduction of IMSPV and improved feed and biological efficiencies. Also, it was observed a CZ main effect (P < 0,04), where animals fed CZ presented heavier hot and cold carcass weight, and larger LM area. The feeding of CZ led to heavier weights for most of the meat cuts analyzed, especially the cuts from the hindquarter. No significant CZ main effect was observed for final 12th back fat thickness, shear force and meat color. For sensory analysis of meat, steers were not harmed when supplemented with CZ. Thus, the addition of CZ in diets for finishing Nellore bulls and steers improves performance and carcass yield without substantially affecting the quality of the final product. / FAPESP: 2013/04593-6
248

Forage and concentrate protein utilization by dairy cattle

Kamande, George Matiru January 1988 (has links)
In the first part of this study, the relative in situ rumen degradabilities of some common Kenyan feedstuffs were estimated using two fistulated steers. The second part of the study attempted to manipulate rumen fermentation processes by heat treating dietary protein, and also by varying the hay particle size. The in situ dacron bag technique was used to estimate the feeding value of some common Kenyan forages. The rate and extent of dry matter (DM) and crude protein (CP) degradation in the rumen was then determined from the incubated samples. Effective DM and CP degradation was also estimated at various rumen digesta flow rates. Green maize chop, fodder sorghum, napier grass, kikuyu grass, Pennisetum trachyphyllum, rhubarb leaves, banana leaves, sweet potato vines, desmodium and lucerne had moderate to high DM and CP degradability (>50%). These feedstuffs would therefore offer greater potential for conservation for feeding dairy cattle in the dry season. Wheat straw, maize stover, red oats grass and naivasha stargrass had significantly (P<0.05) lower rumen degradability. This last group would require supplemental energy and nitrogen in order to meet the dairy cow's nutrients requirements. Wheat bran had a high DM degradability but its CP degradability was low. The digestibility and amino acid availability of its protein requires further investigations. The effects of forage particle length and heat treatment of protein sources on intake, milk yield and composition and, ration digestibility were determined using dairy cows. Normal or heated canola meal and dehydrated alfalfa were fed together with orchard grass hay to 24 lactating Holstein cows. Orchard grass hay was chopped to two mean cut lengths i.e 14.19 and 1.71 mm. In situ results showed that both canola meal and alfalfa proteins in the supplement was made indigestible by heat. Heat treatment did not affect in vivo dry matter (DM), crude protein (CP) and acid detergent fibre (ADF) digestibility for the complete canola rations. Milk yield was also not significantly affected by heating canola meal. However, neutral detergent fibre (NDF) digestibility, voluntary feed intake, butter fat and milk protein contents decreased with heat treatment. Reduced forage particle size in combination with heat treatment resulted in significantly lower DM, CP, and ADF digestibility. There was no significant change in voluntary feed intake, milk yield or its components, (except lactose content), with reduced hay particle size. Lactose content was significantly higher with long chop hay. Heat treatment of "alfalfa and short hay particle size resulted in lower DM and CP digestibility of the complete rations. ADF digestibility and voluntary feed intake were reduced with heat treatment. Hay particle size did not affect voluntary feed intake significantly. Milk yield and its components increased with heat treatment of alfalfa. Only total milk fat increased with the longer chop hay. / Land and Food Systems, Faculty of / Graduate
249

The effects of calcium carbonate on the apparent digestibility, serum concentration and apparent retention of dietary minerals in dairy cattle

Cathcart, Edward Byron January 1981 (has links)
The effect of increasing the calcium content of a hay-grain diet fed to postparturient dairy cattle was studied. Mineral apparent digestibilities, serum concentrations and apparent mineral retentions were monitored while the animals were under the stress of peak lactation. Nine Holstein and seven Ayrshire cows were randomly assigned to the control (0.7% Ca) or the Ca-treatment (1.5% Ca) based on calving order. The diets otherwise contained adequate nutrients. Each animal was fed to appetite for 80 days with no difference (p > . 05) occurring between treatments in intake when expessed as a percentage of body weight. Daily milk production (4% FCM) was higher (p < .05) as was the average body weight (p<.01) for the control animals reflecting the disproportionate number of young animals on the calcium treatment. After a minimum of 60 days on trial, 5 cows from each treatment were exposed to a 5 day digestibility collection period. No change in organic matter or nitrogen apparent digestibility occurred (p>.05) but there were higher (p<.05) levels of calcium and iron, increased (p<.01) levels of copper, and lower (p<.05) zinc and molybdenum apparent digestibilities for animals on the Ca-treatment. Fecal pH was higher (p<.05) in the calcium treated cows indicating a buffering effect occurred as a result of the addition of the calcium carbonate. No change (p>.05) was evident in the secretion of minerals into the milk but urinary phosphorus excretion was significantly higher (p<.05) in the control group. Milk progesterone was analyzed to correspond blood samples (average of 14 per animal) to specific regions of the estrus cycle. Serum phosphorus, iron, copper and zinc varied with reproductive cycling as phosphorus dropped (p<.01) at the onset of regular estrus while the other minerals fluctuated with the cycle (copper and zinc (p< .05), iron (p<.01)). In the serum of Ca-treated animals, calcium and zinc concentrations were higher (p<.01), copper increased (p<.05), and phosphorus was lower (p<.01) than the levels for the control animals. Breed effects were apparent as both phosphorus and copper were higher (p< .01) in the serum of Ayrshires than of Holsteins. Plasma glucose concentrations proved not to be different (p>.05) between treatments. Calcium supplementation of the diet allowed the animals to go from a negative to a positive calcium balance (p<.01). It also increased (p<.05) the amount of phosphorus apparent retention. In all, 6 essential minerals had altered apparent digestibilities and/or serum concentrations with possible long term effects on animal metabolism / Land and Food Systems, Faculty of / Graduate
250

Altering electrolyte balance of diets for lactating dairy cows to reduce phosphorus excretion to the environment

Borucki Castro, Sylvia Irene January 2002 (has links)
No description available.

Page generated in 0.1197 seconds