Digitized by Kansas Correctional Industries

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Call number: LD2668 .T4 1965 W531 / Master of Science

Data is limited evaluating infrequent supplementation of urea or biuret to ruminants consuming low-quality forage (<6% crude protein). Therefore, a series of experiments were designed to compare the effects of daily (D) and alternate day (2D) supplementation of two non-protein nitrogen (NPN) sources (urea or biuret) to ruminants consuming low-quality forage. Experiment 1 was a N balance study using five wethers in an incomplete 5 x 4 Latin square design (five treatments; four 24-d periods) with a 2 x 2 factorial arrangement of treatments (two sources of NPN and two supplementation frequencies) and an unsupplemented control. Supplements, consisting of urea or biuret mixed with ground soy hulls and dried molasses, were isonitrogenous (approximately 26% crude protein; dry matter basis) and offered D or 2D. The 2D supplemented lambs received double the quantity of supplemental N on their supplementation day compared with D lambs; therefore, all D and 2D treatments received the same amount of supplemental N over a 2-d period. Experiment 2 was a 70-d cow performance study using 80 spring-calving cows during the last third of gestation. Cows were stratified by age, body condition score, and expected calving date, and assigned randomly within stratification to one of the five treatments described in Experiment 1 above. They were then sorted by treatment and randomly assigned to 1 of 20 pens (4 cows/pen, 4 pens/treatment). Experiment 3 was a site of digestion study using five ruminally and duodenally fistulated steers to compare D and 2D supplementation of urea or biuret on forage intake, ruminal fermentation, site and extent of nutrient digestion, and rumen microbial efficiency. Five ruminally and duodenally fistulated steers were used in an incomplete 5 x 4 Latin square design with the same treatments described in Experiment 1. The results for Experiment 1 reported that DM, OM, and N intake, DM, OM, and N digestibility, N balance, and digested N retained were greater (P<0.03) for supplemented wethers compared with CON with no difference (P>0.05) because of NPN source or SF. Supplemented lambs had increased plasma urea N (PUN) compared with CON (P<0.01) and urea treatments had greater PUN compared with biuret (P<0.01). Also, PUN was increased (P=0.02) for D compared with 2D treatments. In addition, data suggest that PUN exhibited less fluctuation on the day of a supplementation event for biuret compared with urea. Experiment 2 demonstrated that pre- and post- calving (within 14 d and 24 h of calving, respectively) cow weight and body condition score changes were more positive (P<0.05) for supplemented groups compared with the CON. In Experiment 3, forage OM intake and OM digestibility were not affected (P>0.05) by NPN supplementation, NPN source, or SF. However, total OM and N intake were increased (P<0.01) with supplementation. Duodenal flow of OM tended (P=0.08) to increase with NPN supplementation while N flow was greater (P=0.04) with NPN supplementation compared with the control. In addition, duodenal bacterial N flow was increased with NPN supplementation (P=0.04) and for biuret compared with urea (P<0.01). Bacterial efficiency (g bacterial N/kg OM truly digested in the rumen) was greater for the control compared with NPN treatments (P<0.01) while biuret had greater true N disappearance compared with urea (P=0.01). Intestinal disappearance (% of duodenal flow) of OM and N was not affected by NPN supplementation, NPN source, or SF. However, apparent total tract N digestibility was increased with NPN supplementation (P<0.01) and not affected by NPN source or SF. In addition, ruminal NH���-N increased (P<0.04) on the day all supplements were provided and the day only daily supplement were provided with supplemental NPN. However, an NPN source x SF interaction (P=0.03) on the day all supplements were provided indicated NH���-N increased at a greater rate for urea as SF decreased compared with biuret. Ruminal NH���-N on the day only daily supplements were provided was greater for D compared with 2D (P=0.02). This data suggests that ruminal degradation of biuret to NH���-N was more moderate and prolonged compared with urea, possibly improving use by ruminal microflora. On the day all supplements were provided, D treatments had increased (P=0.05) ruminal indigestible acid detergent fiber passage rate and ruminal liquid volume compared with 2D treatments. Overall, NPN supplementation when feeding low-quality forage (<6% CP) was more beneficial than compared to a negative control, for increasing efficiency of forage digestion, N use, and animal performance. While at the same time indicating that the infrequent supplementation of urea or biuret was not detrimental to forage nutrient utilization, N efficiency or cow performance. This research will provide researchers and ruminant livestock producers with original information that can be used in designing winter supplementation strategies that decrease supplementation costs. Keywords: Urea, Biuret, Forage, Non-Protein Nitrogen, Supplementation, Frequency / Graduation date: 2003

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Thesis (MScAgric)--Stellenbosch University, 1999. / ENGLISH ABSTRACT: The rate of hydrolysis of urea in the rumen of animals is a major limitation when considering the substitution of natural protein with urea in the formulation of rations. The aim of this study was to evaluate polymer coated urea prills with variable coating thickness and evaluate its potential as a slow-release NPN compound. A new slowrelease urea compound, made by coating prilled feedgrade urea with a co-polymer of urea-formaldehyde resin and a castor-coconut alkyd was initially evaluated for urea-nitrogen concentration in distilled water in order to evaluate its potential as a slow-release urea product for ruminants. Amino/alkyd or polyester blends are among the cheapest of the modern synthetic systems and are considered because it is non-toxic, low-cost, biodegradable and easy to manufacture. A 2 x 2 x 2 x 2 factorial design was used and 16 individual products were made and evaluated. The Wurster method was used to encapsulate urea prills. The slopes of the urea release curves represented the release rate of the encapsulated products and were compared to identify the process variables, which had an effect on release rate. Two of the coating variables, coating weight and alkyd: resin ratio, had a major effect (P = 0.0001) on the release rate of urea. The crushing strength of encapsulated products was significantly (P = 0.0001) higher than that of untreated urea. Results motivated the evaluation of the products in the rumen of sheep in terms of rumen ammonia and blood urea N concentrations. Four slow-release products were made after interpreting results from the first study, and differed on account of the coating weight and the composition of the co-polymer. Fifteen fistulated wethers were randomly allotted into 5 groups and intraruminally received an equivalent of 15g urea. Rumen ammonia and blood ammonia were taken at 0, 1, 2, 4, 6, 8, 12, 16, 20, 24, 36 and 48 h after administration of the various treatments. Slow release urea (SRU) resulted in significantly lower rumen ammonia peaks (P = 0.0001) than untreated urea, while the peaks were also significantly delayed. Untreated urea resulted in the maximum concentration at two hours after administration of the urea (P = 0.0685) while the SRU's reached a maximum at six hours after administration in the rumen. No significant differences between the four different SRU types were found. Responses in blood urea-N was similar to that observed for rumen ammonia nitrogen. The encapsulation was effective in decreasing the rate of ammonia release from the urea for up to six hours after administration. In a third trial four Dehne Merino wethers were used in a 2 x 2 Latin square design. They received a SRU product equivalent to 0.4 g urea per kg body weight orally. Rumen liquor and blood samples were taken at 0, 1, 2, 4, 6, 8, 12, 16, 20, 24, 36 and 48 h after intake. Difficulty was initially experienced with ingestion and palatability of the SRU products due to the strong formaldehyde and butanone odour present in the coating. The maximum rumen ammonia (NH3) concentration for the SRU were lower than that of untreated urea (17.5 mg N/dl vs. 66.9 mg N/dl). The time to reach blood urea levels also differed considerably (6 h vs. 24 h for blood urea nitrogen) between treatments. The encapsulation of urea prills shows potential solutions to reduce the solubility of urea and also reduce the hygroscopic nature of urea and improve the palatability and storage characteristics thereof. Keywords: Slow-release urea, encapsulate, copolymer, urea formaldehyde rumen ammonia, blood urea nitrogen, solubility, palatability, storage characteristics. / AFRIKAANSE OPSOMMING: Die vinnige tempo waarteen ureum in die rumen na ammoniak omgesit word, is die grootste beperking in die optimale benutting van ureum, as vervanging van natuurlike protein in herkouerrantsoene. Die doel van hierdie studie was om 'n stadig vrystellende ureumproduk te ontwikkel wat die rumenammoniakvlak gedurende 'n aansienlike periode van die dag bokant 'n sekere vlak kan hou. 'n Nuwe stadig vrystellende ureumproduk, vervaardig deur ureumkorrels met 'n kopolimeer van ureum-formaldehiedhars en 'n kastor-en klapperalkied te bedek, is geevalueer om die potentiaal as stadig vrystellende nie-protein stikstof (NPN)-produk vir herkouers te ondersoek. Die veiligheid, biodegradeerbaarheid, lae koste en maklike vervaardiging van amino/alkied-kopolimere maak dit een van die goedkoopste sintetiese sisteme om vir stadig vrystellende sisteme te oorweeg. 'n 2 x 2 x 2 x 2 Faktoriale antwerp is gebruik om 16 individuele produkte te vervaardig. Die Wurster-metode is gebruik om individuele korrels te enkapsuleer met die polimeer en die potentiaal van die produkte is aanvanklik geevalueer deur die ureumstikstofvrystelling in gedistilleerde water te meet. Die hellings van die vrystellingsgrafieke is vergelyk om die veranderlikes te bepaal wat die grootste invloed op die vrystellingstempo van ureum uit die ge·inkapsuleerde produkte het. Resultate dui dat twee verandelikes 'n betekenisvolle effek het op die vrystellingstempo, nl. dikte van die omhulsel, en die samestelling van die kopolimeer (P = 0.0001 en P = 0.0135, onderskeidelik) het. Die samedrukbaarheid van die ge ·lnkapsuleerde produkte was ook betekenisvol hoer (P = 0.0001) as die van onbehandelde ureumkorrels, wat lei tot verbeterde bergings- en hanteringseienskappe. lnterpetering van resultate lei tot die vorming van vier stadig vrystellende produkte. Vyf groepe van 3 volwasse rumengefistuleerde Dohnemerinohamels is in 'n proef gebruik om die potentiaal van die produkte verder te ondersoek. 'n Ekwivalent van 15 g ureum is direk in die rumen van elke dier geplaas en ammoniak-en bloed monsters is 0, 1, 2, 4, 6, 8, 12, 16, 20, 24, 36 & 48 ure na dosering geneem. Die stadig vrystellende ureumprodukte het 'n betekenisvol laer maksimum waardes vir beide ammoniak-en bloedstikstofureum getoon (P = 0.0001 ). Onbehandelde ureum het 'n maksimum rumenammoniakstikstof konsentrasie reeds twee ure na toediening bereik in vergelyking met ses ure vir die stadig vrysellende produkte. Geen betekenisvolle verskille in hierdie parameters is tussen die ge·lnkapsuleerde produkte gevind nie, terwyl geen interaksie is tussen hoofeffekte voorgekom het nie. In 'n derde proef is vier Dohnemerinohamels gebruik om die vrystellingstempos, in terme van rumenammoniak-en bloedureumstikstof te bepaal waar die stadig vrystellende produk en onbehandelde ureum direk aan die diere gevoer is . 'n Ekwivalent van 0.4 g ureum/kg liggaamsmassa is gevoer. Aanvanklik is inname- en smaakliksheidprobleme ondervind, moontlik as gevolg van die sterk butanoon-en formaldehiedreuk van die omhulsel. Die rumenammoniakstikstof het 'n laer maksimum (17.5 vs. 66.9 mg N/1 00 ml) as die van onbehandelde ureum gehad terwyl die tyd wanneer maksimum konsentrasie bereik word ook aansienlik later was. Die polimeer inkapsulering van ureumkorrels toon potensiaal as 'n stadig vrystellende ureumproduk deurdat dit die oplosbaarheid van ureum in die rumen verlaag. Bykomende voordele is dat die omhulsel die higroskopisiteit verlaag en die samedrukbaarheid verhoog, beide eienskappe wat die hantering-en bergingseienskappe bevorder. Sleutelwoorde: Stadig vrystellende ureum, enkapsulering, kopolimeer, ureumformaldehied, rumenammoniak, bloed ureum stikstof, oplosbaarheid, smaaklikheid, bergingseienskappe.

Thesis (Ph. D.)--Swedish University of Agricultural Sciences, 2000. / Errata tipped in. Includes bibliographical references.

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