At least five million heifers are raised annually in the United States to maintain the dairy cattle population and provide for our future needs. These animals are in reality the very foundation of the dairy business and the prosperity of everyone connected with it are dependent, at least to a certain extent, upon how well and how economically these animals are produced. Any practice that might possibly increase the efficiency with which these animals are raised is certainly worthy of thorough study and consideration. In the past the livestockman has paid little attention to the effect that frequency of feeding may have on the efficiency with which his animals convert feed to milk, meat, and. eggs. This is surprising when one considers the feeding behavior of the animal in its native or unconfined state. In its wild state the animal took in food throughout the day and also undoubtedly at night. The quantity eaten and the frequency of intake was entirely dependent upon the desire of the animal and the availability of feed. This condition still exists to a very large extent in the case of the free-grazing animal. However, with the closely confined or hand-fed animal both the quantity of feed eaten and the frequency of intake are regulated according to the judgment of the husbandman. Since this is a definite change from the feeding habits of the animal in its native state, it is conceivable that some change in the efficiency of feed utilization, if not the overall physiology, of the animal has occurred as a result of domestication. Like the livestockman the research worker has considered frequency of feeding to have little or no influence on his research results. A limited amount of work (15, 70, 27) has demonstrated that frequency of feeding is important in livestock production. If additional work confirms these results, it will become necessary to interpret past feeding experiments in the light of these new findings and to give more attention to frequency of feeding in future nutritional research. Such information would be of considerable practical importance since it would be a comparatively simple matter to design automatic feeders which would feed animals at periodic intervals. The present study was initiated to obtain data on the differences in body weight gain, digestion coefficients, heart rate, rectal temperature, rumination time, and rate of passage of food of dairy heifers fed equalized intakes of feed two and ten times daily. / Master of Science

Master of Science

M.S.

Six lactating Holstein cows fitted with rumen cannulae and T-type cannulae in the proximal duodenum were used to measure digesta and nitrogen compounds flow to the small intestine during early and midlactation. Fish meal and soybean meal provided 54 and 56% of the protein in the diets composed of corn grain, corn silage and orchardgrass hay, and which contained 15.4 and 15.5% crude protein and 20.9 and 20.5 acid detergent fiber. Spot samples of digesta were collected from the rumen, duodenum and rectum over a period of 72 hours. Co-EDTA and ytterbium were used as liquid and particulate digesta markers to estimate flow and digestibility of nutrients. Cytosine was used as microbial marker. True organic matter digestibility in the stomachs was 48.4, 49.8, 44.9, and 53.2% for fish meal and soybean meal diets and early and midlactation respectively. Protein degradability in the stomachs were 47.2, 65.8, 56.7, and 56.2% for fish meal and soybean meal diets and early and midlactation respectively. Amino acids intake was greater for soybean meal diet but total amino acids reaching the the duodenum were similar for both diets. Valine, methionine, lysine and histidine were less degraded for fish meal but were extensively degraded in soybean meal diet. Least degraded for both diets were glycine, valine, serine, proline and histidine. The advantage of greater quantity of protein escaping ruminal degradation with fish meal supplementation was counterbalanced by less microbial synthesis in the rumen partly explaining the similar response obtained with diets especially in early lactation. / Ph. D.

A series of experiments were conducted to measure the mode of action by which fishmeal exerts its effect on milk composition of dairy cows. Production Study One measured the effect of increased fishmeal intake on milk production and milk composition in dairy cattle. Milk fat percentage and yield were decreased by increased fishmeal intake. This decrease was not associated with changes in ruminal fermentation patterns. Plasma long-chain n-3 polyunsaturated fatty acids were increased with increased fishmeal intake. Mammary slices from lactating bovine mammary gland were incubated with eicosapentaenoic acid. Changes in ¹⁴C-acetate metabolism were measured. Acetate oxidation and incorporation into milk lipid were not changed by eicosapentaenoic acid. However, tissue from mammary gland of cows milked 6 to 8 h prior to slaughter had 2 fold higher activity than tissue milked 1 h before slaughter. Disappearance of dry matter, crude protein, and lipid in fish meal from undegradable bags in the rumen was measured. Dry matter and crude protein degradation of fish meal were similar to published values. Lipid escaped rapidly with greater than 70% removed by 8 h. A subsequent fish oil infusion study revealed that intraruminal fish oil treatment did not significantly alter ruminal fermentation, or change fatty acid profiles in duodenal digesta, plasma, or milk. Duodenal infusion increased plasma concentrations of n-3 fatty acids but did not affect milk lipid fatty acid composition. A second production study compared the effects of fish meal versus fish oil on milk production and composition, and changes in fatty acids in plasma and milk. Fish meal significantly increased plasma n-3 fatty acids compared to the fish oil treatment. Residual fatty acids contained in fish meal seemed to be protected from rumen degradation and probably remained intact for digestion and absorption since plasma n-3 fatty acid concentrations increased. No changes in milk yield or composition were due to the experimental treatments. Fat in fish meal and fish oil source differed significantly in their ability to alter milk composition and plasma fatty acid profiles. / Ph. D.

Cottonseed hulls (CSH), chopped orchardgrass (OG) or alfalfa (ALF) hays were added to corn silage-based rations to determine effects on dry matter intake (DMI), nitrogen balance (NB), rumen volatile fatty acids (VFA), and rumen fluid (RFD) and solids (RSD) dilution rates. DMI was highest for added fiber rations and higher for CSH than hay rations. Digestibility of DM was depressed for added fiber rations with lowest for CSH. Most favorable NB was for CSH rations. Rumen VFA were not altered by fiber additions. Highest RFD was for 0% rations and lowest for 9% rations, however CSH had greatest positive influence on RFD. RSD trend was similar to that for RFD. In Experiment II, 4 corn silage-based rations containing 9% OG, ALF, or CSH plus a Control (9% OG) were compared for effect on DMI, rumen VFA, chewing time (CT), RSD, and RFD. Ration density decreased with OG and ALF whereas CSH had no effect compared to Control. DMI was higher for CSH compared to OG and ALF. Total CT (min/d) and Roughage Value Index (CT/kg DMI) were reduced for ALF compared to OG. Total VFA were lower for added fiber rations compared to Control. Acetate:propionate (APR) and non-glucogenic (NGR) ratio were not affected by fiber additions. RFD was reduced for ALF compared to OG whereas CSH was higher than OG and ALF. Reduced RFD was associated with reduced total CT for ALF. RSD was not affected by fiber additions. Chopped OG was supplemented at 0, 9, or 18% of ration DM in a finely chopped corn silage-based ration. Analysis of covariance was performed using 18 lactating Holsteins. Ration density decreased with each increment of OG. DMI was highest for 18% OG ration. Cows on 0% showed decreased DMI whereas cows on 9 and 18% rations increased DMI from covariate period. Rumen acetate, APR and NGR increased while propionate and total VFA decreased with increasing OG. RFD and RSD increased with increasing OG supplementation. Response to 9 and 18% supplementation of OG, ALF, or CSH to corn silage-based rations appears to follow similar pattern as when all-forage rations were compared to all-concentrate rations for lactating dairy cows. A more quantitative evaluation of physical form is needed for dairy rations and feedstuffs leading to an acceptable routine evaluation procedure. / Ph. D.

Two meta-analysis of effects of yeast culture and monensin in lactating dairy cows were first performed. Secondly, two experiments were performed to evaluate the effects of live yeast (LY) or monensin (M) or both (LY+M) on gas production and fermentation by rumen micro-organisms in vitro in low (40 %) and high (60 %) concentrate diets of dairy cows. Rumen contents were collected from one cannulated lactating Holstein cow. Gas production was measured from 0 to 48 h of incubation. Volatile fatty acids and ammonia nitrogen concentrations were measured after 48 h. Meta-analysis of monensin indicated decrease dry matter intake (DMI) and increasing milk yield, consequently improving feed efficiency. Meta-analysis of yeast culture did not show improved performance. These results highlighted the importance of the meta-analysis as a useful tool that can be employed to both summarize effects across studies and to investigate factors explaining potential heterogeneity of response. The batch fermentation showed that in high concentrate diet, M significantly increased ammonia nitrogen, decreased acetate, but tended to increase propionate concentration (7.9, 63.2, 18.6 vs. 6.3, 66.8, 14.2 mmol/l; respectively). Addition of LY increased acetate concentration (64.2 vs 66.8 mmol/l). Supplementation with M, LY and LY+M reduced total gas production by 37.1, 22.5 and 26.9 %, respectively, compared to control at 48 h. In low concentrate diet, M and LY+M decreased and increased acetate (60.1 and 69.7 vs. 7.1 mmol/l; respectively). Adding LY and LY+M produced 8.6 % less gas, and M treatment 3.4 % more gas than the control. Overall, at 48 h, high concentrate resulted in less gas than low concentrate diets. High concentrate diets showed increased ammonia (7.9 and 6.4 vs. 5.21 and 4.7 mmol/l) decreased acetate (63.0 and 63.2 vs. 67.0 and 69.7 mmol/l) with a tendency to increased propionate (18.6 and 18.9 vs. 14.6 and 14.1 mmol/l) compared to low concentrate in M and LY+M treated diets. These results indicate that the effects of M and LY on rumen fermentation are substrate dependent, the high-concentrate diet showing the greatest response / Agriculture / M. Sc. (Agriculture)

Thesis (MPhil)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: CPM Dairy was developed to maintain amino acid balance. because the correct amino acid relationship has an influence on milk production and milk composition (Schwab e/ af. 1992, Rulquin e/ af. 1993). Rulquin e/ af. (1993) found that an increase in lysine and methionine concentration in the diet had no meaningful effect on milk production and milkfat production. However, milk protein production is described as a function of lysine and methionine concentration. In order to balance the amino acid relationships, the CNCPS model has been adopted, using the following guidelines: I. a dairy cow feed characteristic scheme, described by Van Soest e/ af. (1991) and Sniffen e/ aI. (1992), II. a model for rumen fermentation and bacterial growth in the dairy cow, described by Russel e/ af. (1992), Ill. feed val ues for dairy cow feeds, described by Sniffen e/ af. (1992). IV. a set of formulas describing the feeding needs of dairy cows under different circumstances, assembled by Fox e/ af. (1992). Bateman e/ af. (2001) studied the accuracy of formulation models according to crude protein (CP) and amino acid (AA)-flow to the duodenum in lactating dairy cow diets. CPM Dairy does not calculate direct flow of CP to the duodenum, but the following adjustment was made: the change-over of metabolizable protein (MP) to CP is done by increasing bacterial protein from 60% to 100% of bacterial-CP. Intestinal digestion of fraction B3-protein is increased from 80% to 100%, whereas fraction C-protein is increased from 0 to 100% to change feed-MP to feed-CP. CP from feed and microbes are summed to indicate total CP-flow to the duodenum. AA-flow, as calculated by CPM Dairy, is used without adjustments. A rise in MUN-Ievels are typical to spring and summer months. which can be ascribed to high soluble protein and low soluble carbohydrates in grasses and legumes. This gives rise to an excess N-uptake in the bloodstream. Grass silage, when fed as primary feeding source. has the same reaction. Blood-urea-nitrogen (BUN) is the amount of urea-N found in the blood of the cow. MUN is the fraction ofN in the milk in the form of urea. MUN is normally 85% the concentration of BUN. Studies show that an increase in BUN/MUN levels leads to a negative effect on the reproductive ability of the cow. An increase in BUN-levels leads to an increase in urea in the reproductive tract of the animal. Urea passes between the blood plasma and the reproductive tract. It is therefore obvious that a high BUN-concentration leads to high levels of urea in the reproductive tract. In order to eradicate this problem. the use of deodorise in the supplemental feed of the lactating dairy cow \vas recommended. Deodorise is a natural product manufactured by Alltech. The product is derived from the Yuccha Schidigera plant. Two glycocomponents (CI and C II) of this plant binds gasses such as N1-I3. (Alltech information sheet) During .June to August 2002 data were collected regarding the effect of deodorise on lactating dairy cows. No meaningful difference between the two groups in this experiment was found. / AFRIKAANSE OPSOMMING: CPM Dairy is ontwikkel am aminosuurbalans te handhaaC aangesien die korrekte aminosuurvcrhoudings 'n invloed op melkproduksie en mclksamcstelling het. (Schwab el al. 1992, Rulquin el al. 1993). Rulquin el al. (1993) hct gcvind dat 'n tacname in die konsentrasic van lisien en mctionien in dic rantsoen gccn nocmenswaardigc cffek op melkproduksie en meIkvctproduksie het nie. MelkproteYcnproduksie word cgtcr beskryf as 'n funksie van !isien- cn metionienkonscntrasie. Ten einde die aminosuurvcrhoudings te balanseer. is die CNCPS model aangcneem. wat die volgcndc riglyne gebruik : I. 'n Melkbees vocdingskarakteriseringskema, soos bcskryf deur Van Soest el 01. (1991) en Sniffen el 01. (1992). II. 'n Model van rumcnfermentasie en bakteriele groei in die melkbces, soos deur Russel e/al. (1992) beskryf. Ill. Voedingswaardes vir melkbeesvoedingstowwe, soos bcskryf deur Sniffen e/ 01. ( 1992). IV. 'n Stcl vergelykings wat die voedingsbehoeftcs van mclkbcestc onder vcrskillende omstandighede beskryf, saamgestel deur Fox e/ 01. (1992). Bateman e/ 01. (200 I) bestudeer die akkuraatheid van formulasiemodelle ten opsigte van RP- en aminosuur (AA)-vloei na die duodenum in lakterende melkkoeirantsacne. CPM Dairy bcreken nie dirckte vloei van RP na die elunderm nie. elus is dic volgenele aanpassing gcmaak : Die omskakeling van Metaboliseerbare proteYen (MP) na RP word gedoen deur bakteriele prote"len te verhoog vanaf 60% tot 100% van baktcriCle-RP. Dermkanaalvertering van ti'aksie B3 proteYen is verhoog vanaf 80% tot IOO(/j), terwyl fraksie C protc'len vanaf 0 tot 100% verhoog is ten einde voer-M P om te skakcl na voer- RP. RP vanafvoer en mikrobes word gesommeer en verskafvoorspellings vir totale RPvioei na dic duodenum. Die AA-vloei. so os deur CPM Dairy bereken word, is sonder wysigings gebruik. n Styging in MUN-vlakke word tipies in die lente- en somermaande ondervincL wat toegeskryl' kan word aan hoc oplosbare protc"ien en lae oplosbare koolhidrate in grasse en peulgewasse. Dit gee aanleiding tot 'n oonnaat N wat in die bloedstroom opgeneem word. Graskuilvoer, wanneer gevoer word as die primcre voedingsbron, het dieselfde uitwerking. Bloed-ureumstikstof (BUN) is die hoeveelheid ureum-N teenwoordiu: in die bloed van die koei. MUN is die fraksie N in melk in die vonn van ureum. MUN is gewoonlik 85% van die konsentrasie van BUN. Navorsing toon dat 'n toe name in BUN/MUN vlakke 'n nadelige uitwerking het op die reproduktiewe vermoc van die koei. 'n Toename in BUN-vlakke veroorsaak 'n toename in ureum in die dier se reproduksiekanaal. Ureum beweeg tussen die plasma en die reproduksiekanaal. Dit is dus duidelik dat 'n hoc BUN-konsentrasie sal lei tot hoc vlakke van ureum in die reprod uksiekanaal. Ten einde hierdie probleem uit te wis, is die gebruik van De-Odorase in die kragvoer van die lakterende koeie aanbeveel. De-Odorase is 'n natuurlike produk wat deur Alltech vervaardig word. Die produk is at1(omstig van die Yucca schidigera plant. Twee glikokomponente (CI en CII) van hierdie plant bind gasse so os Nl-h (Alltech inligtingstuk). Gedurende .Iunie tot Augustus 2002 is data ingesamel aangaande die uitwerking van De- Odorase op melkbeeste. Daar is geen betekenisvolle verskil tussen die twee groepe met hierdie ekspcriment waargeneem nle.

Thesis (MPhil (Animal Sciences))--University of Stellenbosch, 2006. / South Africa produces only 0,50 % of the world’s milk. Although the number of milk producers is decreasing in South Africa, the milk production per se is increasing. The total number of small producers is decreasing while the number of big producers is increasing. The cost to raise replacement heifers is very high. Replacement heifers are the cows of tomorrow and should be seen as a valuable investment for the longterm survival and profitability of the dairy farm. A successful heifer rearing program is one in which: • Heifers are economically raised to be of adequate size and body condition to calve at a reasonable age. • Heifers produce high levels of milk during the first lactation. In the current study, the effect of Flavomycin and Mamalvite supplementation to young calves was investigated. According to manufacturer’s claims, Flavomycin would result in improved gains, improved conception rates, shorter calving intervals, increased milk production and improved weaning weights. Mamalvite, according to the manufacturer, should reduce risk of infections, increase feed utilization, increase feed intake and production, and also increase rumen microbial efficiency. Thirty two Holstein calves, four days of age, were randomly divided into four groups of eight. All calves received 4 kg whole milk daily and had free access to calf starter pellets. Treatments were: 30 ml Mamalvite daily supplemented in the milk and 5 g Flavomycin daily per os (Treatment 1), 30 ml Mamalvite daily supplemented in the milk (Treatment 2), 5 g Flavomycin daily per os (Treatment 3) and a control group that received milk only (Treatment 4). All the calves were weighed weekly. According to the results obtained in the current study, neither Flavomycin, nor Mamalvite, nor a combination of the two resulted in an improvement in calf weight gains. It was concluded that it does not appear to be an economically viable option to supplement Mamalvite or Flavomycin to calves that are reared in a well managed environment.

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