Data collected on weight, feed consumption, and daily gain of 66 steers and 121 bulls were studied by analyses of variance, covariance, correlation, and partial regression. The bulls were of Hereford, Angus, and Shorthorn breeds, and the steers were the offspring of fast and slow gaining bulls that were progeny tested. The feeding tests for the bulls were from 112 to 170 days, and for the steers, approximately 200 days. The bulls and steers were on full feed for the test period, and all animals were fed individually. The first four groups were hand fed and the remaining groups were self fed. / Master of Science

Brush border and basolateral membrane vesicles were isolated by subjecting homogenized mucosal cells from bovine small intestine to a divalent cation aggregation followed by a series of differential and density gradient centrifugations. Membrane marker enzyme assays were used to monitor the effectiveness of the fractionation procedure. Enrichments were determined by comparing the enzyme specific activities of the membrane fractions to the homogenate. Sodium-potassium adenosine triphosphatase and alkaline phosphatase served as the enzyme markers for the basolateral and brush border membranes, respectively. Basolateral membrane vesicles enriched 11.1 fold were isolated from the interface of the 31 and 34% sucrose bands of a discontinuous sucrose gradient. Brush border membranes enriched 10.1 fold were isolated from the surface of the 28% sucrose band of a discontinuous sucrose gradient. The use of frozen rather than fresh mucosal tissue in the isolation procedures was found to enhance the purification of basolateral and brush border membrane fractions. The transport capabilities of vesicles were demonstrated by incubating vesicles with radiolabeled substrate, then separating the vesicles and transported substrate from the incubation buffer by filtration. Substrate uptakes were quantified by liquid scintillation counting. Basolateral membrane vesicles were observed to accumulate substrate into an osmotically active space and to have Na⁺-dependent alanine transport capabilities. The use of basolateral and brush border membrane vesicles as tools to investigate nutrient uptake allows the investigator to manipulate both the extravesicular and intravesicular environments, thus making possible the evaluation of the complex interactions which are involved in nutrient transport mechanisms. / M.S.

Objectives were to determine dry matter, fiber and nitrogen fractions, and in vitro and in situ degradability of forages and by-product feeds, and to compare in vitro methods of estimating rumen degradability with the in situ bag technique. Feeds analyzed with number of samples in parentheses included alfalfa as baled hay (23), alfalfa ensiled in conventional (43), and. oxygen limiting silos (39), ammonia· treated (25), and untreated corn silage from conventional (17) and bunker silos (17), rye (25), sorghum (7), wheat (6), barley (5), and orchardgrass (4) silages, orchardgrass (19) and fescue hay (3), and dried distillers grains dark colored (2) and light (1), wet brewers grains (1), and whole cottonseeds (3). Samples were analyzed for dry matter, crude protein, buffer-soluble protein, protease insoluble nitrogen, neutral and acid detergent fiber and insoluble nitrogen, and in situ degradability of nitrogen, dry matter, and fiber. Protease insoluble nitrogen, buffer-insoluble protein, and neutral detergent insoluble nitrogen were lowest for alfalfa from conventional upright silos. Oxygen limiting silo samples had greater dry matter, insoluble protein, and bound nitrogen compared to conventional upright silo samples. Oxygen limiting silos had 35.9% of samples with bound nitrogen greater than 15% of total nitrogen compared to 14% of conventional upright silo samples. Baled hay and oxygen limiting silo samples had similar protease insoluble nitrogen, however, ensiled samples had greater bound nitrogen. In situ nitrogen degradability was greatest for ensiled forages compared to hays. Ensiled forages had the greatest A fraction (rapidly solubilized), alfalfa hay the greatest B fraction (slowly degraded), and orchardgrass hay the greatest C fraction (not degraded). Degradation of dry matter and fiber followed similar patterns for each forage and by-product. Significant results were found by comparing in vitro and in situ techniques for estimating degradability. Due to differences between hay and silage, use of one technique can not be recommended at this time to predict degradability. For silage, the best measure related to in situ degradability was buffer-soluble protein; for hay, the best measure was neutral detergent insoluble nitrogen. / Ph. D. / incomplete_metadata

Thesis (MScAgric)--University of Stellenbosch, 2000 / ENGLISH ABSTRACT: A flock of 500 Hybro broiler breeders were employed to study the effect of different levels of protein and energy on production and body composition. The daily lysine intake of the birds were 900, 1050, 1200 and 1350 mg respectively, each fed in diets with a daily energy intake of 1800 and 2000 kJ ME to provide a 4 x 2 factorial design. Lysine was used as the reference amino acid in the experiment and all other amino acids were kept in a constant ratio in every experimental diet. The total production was divided into 3 periods of 13 weeks each (week 23 - 35; week 36 - 48 and week 49 - 61) to determine the effect of the treatments over time. Production was evaluated by hen day production; egg weight (g/egg); egg mass (g/day); fertility; hatchability; chicks/hen/week; feed conversion and day old chick weight. Hen day production was significantly (P < 0,05) lower at the high energy intake for period week 49 to 61. Energy and protein levels significantly increased egg weight. Effect of protein was consistent during all three periods of production. Egg mass output had a significant (P < 0,05) response to increasing levels of protein for the total period of production. The birds on the high energy diet produced a significant higher egg mass per hen during the first period of production (week 23 - 35). Hatchability was reduced (P < 0,05) by the higher energy intake for the total period of production and this effect was very significant (P < 0,01) during the final period of production. Similar to hen day production, the higher energy had a significant (P < 0,05) negative effect on the amount of chicks produced. The well-known correlation between egg weight and chick weight was confirmed with the regression equation: Chick weight = 10,5 + 1,22 x Egg weight. Both energy and protein had a significant (P < 0,01) positive effect on chick weight. The feed conversion was lower at increasing levels of amino acid intake (P < 0,01). Higher energy intake significantly (P < 0,05) increased hen weight and protein had a very significant effect during the first period of production (P < 0,01). The isotope dilution technique (tritiated water) was used to estimate the body composition of the breeders. This was done at 5 different periods (week 27, 35, 43, 52 and 61) of the production period to establish changes in requirements over time. Significant correlation were found between carcass moisture and waterspace (R2 = 0,76); fat % and carcass moisture (R2 = 0,78); protein % and waterspace (R2 = 0,35) and fat % and waterspace (R2 = 0,46). The regression equations obtained from these correlation were employed to determine excess energy and lysine consumed at different ages. Energy requirements were calculated according to the effective energy (EE) system and the conventional ME system. According to effective energy the lower energy intake was not sufficient and the maximum requirement was calculated to be 1942 kj EE/day. The metabolizable energy calculations indicated sufficient intakes at every treatment with the maximum requirement 1746 kj ME/day. The lysine requirement was found to be in excess of 1050 mg lysine per day. The recommendation for daily lysine intake is 1200 mg/day and the energy intake of breeders should be 1900 to 2000 kj ME/day from week 23 to 35 and can be reduced to 1800 kj ME/day in the final period of production. / AFRIKAANSE OPSOMMING: Om die effek van verskillende vlakke energie en proteïen op produksie en liggaamsamestelling te ondersoek is 'n trop van 500 Hybro braaikuiken teelouers gebruik. Die daaglikse lisien inname van die henne was onderskeidelik 900, 1050, 1200 en 1350 mg, wat elk by 'n daaglikse energie inname van 1800 en 2000 kJ ME verskaf is, in 'n 4 x 2 faktoriale ontwerp. Alle aminosure is in 'n konstante verhouding met die verwysings aminosuur lisien in die rantsoen ingesluit. Om te evalueer of daar veranderinge oor 'n tydperk plaasvind weens die verskillende behandelings is die produksie periode in drie periodes van 13 weke elk verdeel (week 23 - 35; week 36 - 48 en week 49 - 61). Die produksie standaarde wat gemeet is, is hen dag produksie, eiergewig (g/eier), eiermassa (g/dag), vrugbaarheid, uitbroeibaarheid, kuikens/hen/week, voeromset en dagoud kuikenmassa. Hen dag produksie was betekenisvol (P < 0,05) laer by die hoër energie innames in die laaste periode van 49 tot 61 weke. Energie en proteïen het eiergewig betekenisvol (P < 0,01) verhoog. Die effek van hoër vlakke proteïen was konstant in alle produksie periodes. Die daaglikse eiermassa (g/dag) het ook saam met stygende vlakke proteïen verhoog en hierdie effek was vir die totale periode van produksie. Energie het die eiermassa in die eerste periode van produksie (week 23 - 35) verhoog. Uitbroeibaarheid is verlaag (P < 0,05) vir die totale periode van produksie deur die hoër energie inname en die effek was selfs groter (P < 0,01) in die finale periode van produksie. In ooreenstemming met die hen dag produksie is die aantal kuikens geproduseer negatief beïnvloed deur die hoër energie inname (P < 0,05). Die korrelasie wat bestaan tussen eiermassa en kuikenmassa is bevestig deur die regressie: Kuikenmassa = 10,5 + 1,22 x Eiermassa. Energie en proteïen het kuikenmassa betekenisvol (P < 0,01) verhoog. Voeromset was laer by stygende vlakke van proteïen inname (P < 0,01). Die hoër energie inname het henmassa ook betekenisvol (P < 0,05) verhoog en proteïen het dieselfde effek slegs in die eerste periode van produksie gehad (P < 0,01). Die liggaamsamestelling van teelhenne is bepaal met behulp van die isotoop verdunnings tegniek (tritium water). Dit is bepaal op 5 verskillende stadiums in die produksie periode (week 27, 35, 43, 52 en 61) om die moontlike verandering in behoeftes oor tyd vas te stel. Betekenisvolle korrelasies is gevind tussen karkasvog en die waterspasie (RZ= 0,76); vet % en karkasvog (R2 = 0,78); proteïen % en waterspasie (R2 = 0,35) en vet % en waterspasie (R2 = 0,46). Die regressie vergelykings van hierdie korrelasies is gebruik om die hoevelheid surplus energie en lisien ingeneem te bepaal. Die" effective energy" sisteem en die konvensionele ME sisteem is gebruik in die bepaling van energie behoeftes. Volgens die " effective energy" was die energie inname nie voldoende by die laer energie innames nie en die maksimum behoefte is bereken as 1942 kJ EE/dag. Die maksimum energie behoefte volgens metaboliseerbare energie is bereken as 1746 kj ME/dag. Die lisien behoefte moet hoër as 1050 mg/dag wees. Die aanbeveling van die daaglikse lisien inname is 1200 mg/dag en die energie inname moet 1900 tot 2000 kj/dag wees tot 35 weke produksie en kan daarna verlaag word na 1800 kJ ME/dag.

Studies were conducted to: (1) examine an in situ technique with sorghum grain substrates using monofilament nylon bags, (2) evaluate in vitro various reconstituted sorghum grain treatments, (3) determine digestibility and nitrogen balance of steers fed reconstituted sorghum grain and (4) evaluate sorghum grain processing methods on performance of finishing steers. Dry matter efflux, DME (water bath) and in situ dry matter disappearance, ISDMD (ventral sac of rumen) from nylon bags were higher (P < .05) as bag porosity (5 to 80 um) and incubation time (4 to 24 h) increased, and as substrate weight: bag surface area ratio (7 to 56 mg/cm²) decreased. High linear correlations were obtained between DME and ISDMD, and also between nitrogen efflux and in situ nitrogen disapperance. No permanent influx of ruminal dry matter into nylon bags were detected. In vitro dry matter digestibility (mixed rumen inoculum) of reconstituted whole sorghum grain was influenced (P<.001) by grain moisture level (18 to 31%), constant or variable temperature during storage (-18 to 41 C) and length of storage time (3 to 28 d). All interactions of these three factors were significant (P<.05 or higher). Short term flushing with O₂, CO₂ and N₂ did not affect (P>.10) the digestibility of reconstituted whole sorghum grain. With reconstituted whole sorghum grain, grain pH could be used as a satisfactory measure of quality control. Apparent digestion coefficients for dry matter, organic matter, protein and energy were similar (P>.05) for steers fed 90% concentrate diets containing reconstituted whole or flaked sorghum grain. Nitrogen retention as a percent of nitrogen intake was 35% higher (P<.05) for steers fed reconstituted than flaked sorghum grain diets. In two finishing trials with steers, feed intake and feed conversion were higher (P<.05) for dry rolled than for flaked or reconstituted sorghum grain.

Graduation date: 1993

No description available.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Typescript (photocopy). / Digitized by Kansas Correctional Industries

Typescript (photocopy). / Digitized by Kansas Correctional Industries