Call number: LD2668 .T4 1932 B43

Call number: LD2668 .T4 1953 S92 / Master of Science

Call number: LD2668 .T4 1928 W32

Call number: LD2668 .T4 1929 B71

Data for the period 2015-04 to 2015-09 was analyzed in order to examine the possible relationship between teat wash failure and the result on milk yield for dairy cows. Data provided by Sveriges Lantrbruksuniversitet over 49 093 specific milking events were used. Two linear mixed-effects models and one basic OLS-model were estimated. In order to perform the analysis a lot of data manipulation also had to be performed. The data analysis was divided into to two parts. First the variable of interest (teatwash) was examined by constructing two versions of the different models; an unrestricted- and a restricted version were teatwash had been excluded. Because of the large sample and linear mixed-effect models an out-of-sample forecasting method was used as the primary evaluation criteria. The prediction errors were evaluated on the basis of root mean squared error (RMSE) and mean squared error (MSE). The difference between the unrestricted- and restricted models was very small and no indication of a relationship between teat wash failure and milk yield was found. The second part involved the comparison of prediction errors between the two mixed-effect models and the OLS-model. Surprisingly, the basic OLS-model resulted in the lowest prediction error although obvious breach of assumptions.

Thesis (MScAgric)--Stellenbosch University, 2001. / ENGLISH ABSTRACT: The goat is a significant domestic animal throughout the world today. With an estimated world goat population of 590 million goats in 1991 (FAO, 1991 as citied by Haenlein, 1996) it is impossible to consider the goat as insignificant. The need for milk, and it seems particularly goat’s milk, is obvious if one considers the increase in dairy goat populations over the past 20 years. Across the globe the dairy goat population has increased by 52% while in developing and developed countries, there has been an increase of 56% and 17%, respectively (Haenlein, 2000). The goat dairy industry in South Africa is still very underdeveloped, yet it holds tremendous potential for the entrepreneur willing to take the risk and do the job correctly. With the present South African financial situation the opportunities that exist for exporting value added products to countries with stronger currencies is a market with extraordinary potential. In New Zealand, the national herd consists of approximately 16000 dairy goats and 90% of the milk produced is turned to powdered milk and then exported to the East, a valuable source of foreign currency. In South Africa, the same potential exists and with some vision and hard work the dairy goat industry can make a valuable contribution to generating foreign currency. Research into the protein requirements and particularly protein degradability requirements of dairy goats is scarce, yet in recent years there has been an increased interest in the effect of protein supplementation to lactating animals (Mishra & Rai, 1996). In the work of Mishra & Rai (1996) there were benefits obtained from the use of different rumen degradable proteins for lactating dairy goat does. The does on the highly degradable protein diet had a better feed intake while the does on the low degradable protein diet gave a higher milk production. Other research on this field of study has also delivered positive results with more than one species of lactating animal that had increased levels of UDP in the diet (Robinson et al., 1991 and Christensen et al., 1993). Loerch et al. (1995) suggested that improved production by making use of rumen undegradable proteins would have no effect if crude protein were not a limiting factor in production. Pailan & Kaur (1995) and Mishra & Rai (1996) did research on lowered CP levels with increased UDP levels in lactating dairy does. They used of three diets, with the one having a 20% lower CP value but an increased level of UDP (40-45% of total CP). From this work it was concluded that a decreased CP level and an increased level of UDP is able to sustain production when compared with diets with a higher CP value. The current study consists of two trials. In the first trial the effect of weaning age and dietary protein degradability on the growth of Saanen kids was investigated. In the second trial the effect of dietary protein degradability on the production of lactating Saanen does was investigated. Fifty-eight Saanen kids were divided into groups to determine the effect of weaning age (42 vs. 70 days) on animal performance. Within the weaning day treatments, the kids were again divided into two dietary treatments. One group received a low UDP creep diet (LC) and the other a high UDP creep diet (HC). The two creep diets were formulated with rumen degradable: undegradable protein (RDP : UDP) ratios of 70:30 and 60: 40, referred to as LC and HC, respectively. However, the results from the degradability trial indicated no difference in RDP: UDP ratios for the low and high creep (72:28 and 73:27 respectively) diets. At 15.66 ± 3.09 kg the kids were taken off the creep diet and put on the growth diet. At this transition, the kids in each of the 4 established treatments were again randomly divided into two dietary treatments, a high or a low UDP growth diet, resulting in a total of eight treatments for the trial. The two growth diets were formulated with RDP: UDP ratios of 70:30 and 60:40, referred to as low growth (LG) and high growth (HG) respectively. Results from the degradability trial indicated RDP: UDP ratios for the LG and HG of 73:27 and 68:32 respectively. The growth trial was conducted over 140 days and feed intake, bodyweight change and feed conversion efficiency were compared for each of the 8 treatments. From the trial with the Saanen kids it was concluded that weaning dairy goat kids at 42 days of age when feed intake was 240 g/day resulted in similar growth rates when compared with weaning at 70 days. The two creep diets did not differ in RDP: UDP ratios and thus no conclusion can be made regarding the influence of the creep diets on the growth of Saanen kids from 20 to 80 days of age. The two growth diets did in fact differ from one another, in terms of RDP: UDP however, protein degradability had no influence on the performance of the Saanen kids from 80 to 140 days of age. Twenty-one lactating Saanen does were randomly assigned to one of three experimental diets. The treatments had two RDP: UDP ratios and two crude protein (CP) levels. Treatments were formulated to be 1) RDP: UDP = 70:30, CP = 20 % 2) RDP: UDP = 62:38, CP = 20% and 3) RDP: UDP = 62:38, CP = 18.3%. In the production trial the does were milked for 120 days, during which milk yield, milk composition, bodyweight change, feed intake and feed conversion efficiency were compared between the treatments. In the digestibility and nitrogen metabolism trial, 18 does varying from 84 to 110 days in lactation, were used to compare the experimental diets. Furthermore, the experimental diets were compared in a degradability and rate of passage trial using cannulated Dohne merino wethers. Results from the degradability trial indicated that the low UDP, low protein high UDP and high UDP diets had RDP: UDP ratios of 82:18, 78:22 and 79:21 respectively, and that the dietary protein degradability did not differ significantly between diets. Results from the production trial indicated that there was a significant difference in feed intake, dry matter (DM) intake and bodyweight. The does on the low UDP diet had significantly higher feed intakes and DM intakes and were significantly heavier at the end of the trial period. As the diets didn’t differ in protein degradability other factors must have influenced the intakes between diets. Palatability may have influenced feed and DM intake, as the low protein high UDP and high UDP diets both contained higher levels of fishmeal. No significant differences in milk production, milk composition or milk production efficiency were observed. Besides the fact that the diets did not differ in effective protein degradability, large variations in milk production between animals and low numbers of animals per treatment limited the ability to measure a difference between the treatments. Results from the digestibility trial varied between diets with the low UDP diet having a significantly lower digestibility overall than the other two diets. Reasons for the difference in digestibility could be due to the difference in rate of passage (low UDP = 0.064/hour versus the 0.044- 0.045/hour of the low protein and high UDP diets respectively) and the high ADF value of the low UDP diet. Because no difference in effective protein degradability existed between the diets it is not possible to make an accurate conclusion on whether or not the dietary protein degradability had an influence on production parameters tested in this trial. / AFRIKAANSE OPSOMMING: Huidiglik is die bok ‘n belangrike gedomestikeerde dier dwarsoor die wereld. Aangesien die wereldwye bokpopulasie in 1991 op 590 miljoen geraam is (FAO, soos aangehaal deur Haenlein, 1996), is dit onmoontlik om die bok as onbelangrik te beskou. Die behoefte aan melk, en dan veral bokmelk, is duidelik as mens die toename in bokpopulasies oor die afgelope 20 jaar in ag neem. Wereldwyd het die melkbokpopulasie met 52% toegeneem, terwyl dit in ontwikkelende en ontwikkelde lande met 56% en 17% onderskeidelik, toegeneem het (Haenlein, 2000). Ten spyte van die feit dat die bokmelk-industrie in Suid-Afrika nog baie onderontwikkel is, is daar geweldige potensiaal vir die entrepeneur wat bereid is om ‘n risiko te loop en die taak korrek aan te pak. Binne die huidige Suid-Afrikaanse finansiele situasie bestaan daar veral geleenthede om waardetoegevoegde produkte na lande waarvan die wisselkoers sterker is, uit te voer. In Nieu Zeeland is die nasionale kudde ongeveer 16000 melkbokke en 90% van die geproduseerde melk word verwerk na poeiermelk en uitgevoer na die Ooste. In Suid-Afrika bestaan dieselfde potensiaal en met die korrekte visie en harde werk kan die melkbok-industrie ‘n belangrike bydra lewer om buitelandse valuta te verdien. Alhoewel navorsing aangaande die proteien-degradeerbaarheidsbehoeftes van melkbokke skaars is, bestaan daar die afgelope paar jaar ‘n toenemende belangstelling in die effek van proteien supplementering aan lakterende diere (Mishra & Rai, 1996). In die werk van Mishra & Rai (1996) is die voordele om verskillende rumen degraderende proteTenvlakke in lakterende melkbokke te gebruik, aangetoon. Ooie op ‘n hoogs degradeerbare prote'fen-dieet het beter voerinnames getoon, terwyl die ooie op ’n laag degradeerbare prote'fen-dieet hoer melkproduksies gelewer het. Navorsing van hierdie aard op ander lakterende spesies het ook positiewe resultate met ‘n toename in verbyvloeiprote'ien in die dieet gelewer (Robinson et al., 1991 en Christensen et al., 1993). Loerch et al. (1995) het voorgestel dat ‘n verbeterde produksie, deur gebruik te maak van verbyvloeiprote'fn, geen effek sal he as ruprote'fen (RP) nie ‘n beperkende faktor i.t.v produksie is nie. Beide Pailan & Kaur (1995) & Mishra en Rai (1996) het navorsing gedoen op die invloed van verlaagde RP-vlakke en verhoogde nie-degradeerbare protein (NDP) vlakke in die diete van lakterende melkooie. Daar is gebruik gemaak van drie diete, waarvan die een dieet ‘n 20% laer RPinhoud, maar ‘n verhoodge NDP-vlak (40-45% van totale RP) gehad het. Vanuit hierdie werk is die gevolgtrekking gemaak dat ‘n verlaging in RP-vlak en ‘n verhoging in NDP-vlak dieselfde produksie kan onderhou, soos met ‘n hoer RP-inhoud. Die huidige navorsing bestaan uit twee proewe. In die eerste proef is die effek van speenouderdom en dieet-prote'fen-degradeerbaardheid op die groei van Saanen-lammers ondersoek. In die tweede proef is die effek van dieet-proteien-degradeerbaardheid op die produksie van lakteerende Saanen melkbokke ondersoek. Agt-en-vyftig Saanen-lammers is verdeel in twee speenouderdom-behandelings, nl. ‘n 42 dae (42) en ‘n 70 dae (70) speenouderdom. Binne hierdie speenouderdom-behandelings is die lammers verder verdeel in twee dieet-behandelings. Die een groep het ‘n lae NDP kruiprantsoen (LK) en die ander ‘n hoe NDP kruiprantsoen (HK) ontvang. Die twee kruiprantsoene was geformuleer om rumen degradeerbare proteien (RDP): NDP verhoudings van 70:30 (LK) en 60:40 (HK) te bevat, maar die resultate van die degradeerbaarheidsproef het aangetoon RDP: NDP verhoudings van 77:23 (LK) en 78:22 (HK). Die lammers is vanaf die kruipdieet oorgeplaas op ‘n groeidieet by ‘n gemiddelde lewende massa van 15.99±3.09 kg. Tydens hierdie oorplasing is die lammers van die vier bestaande behandelings verdeel in ‘n verdere twee dieetbehandelings, nl. ‘n hoe of ‘n lae NDP groei-dieet (LG en HG onderskeidelik), met die gevolg dat ‘n totaal van agt behandelings in hierdie proef bestaan het. Die twee groeidiete is geformuleer met RDP: NDP verhoudings van 70: 30 (LG) en 60: 40 (HG) onderskeidelik, maar die resultate van die degradeerbaarheidsproef het aangetoon RDP: NDP verhoudings van 78:22 (LG) en 72:28 (HG). Die groeiproef is uitgevoer oor 140 dae en voerinname, verandering in liggaamsgewig en voeromsettingsdoeltreffendheid (VOD) is vergelyk tussen die agt behandelings. Uit die lammerproef is die gevolgtrekking gemaak dat boklammers wat op 42 dae gespeen is, wanneer voerinname 240g/dag is, soortgelyke resultate i.t.v. groeitempo lewer as lammers wat op 70 dae gespeen is. Die twee kruiprantsoene het nie van mekaar in RDP: NDP verskil nie en dus kan geen gevolgtrekking gemaak word omtrentdie invloed van dieet-protel'en-degradeerbaarheid op die groei van Saanen boklammers van 20 tot 80 dae ouderdom. Die twee groei diete het van mekaar verskil in RDP: NDP maar dieet-proteien-degradeerbaardheid het geen invloed op die groei van die Saanen boklammers van 80 tot 140 dae ouderdom gehad nie. Een-en-twintig lakterende Saanen-ooie is ewekansig in drie groepe. Die behandelings het twee RDP: NDP-verhoudings en twee ruprotei'en (RP) -peile ingesluit. Behandelings was 1) RDP: NDP = 70:30, RP = 20% 2) RDP: NDP = 62:38, RP = 20% en 3) RDP: NDP = 62:38, RP = 18.3%. Tydens hierdie produksieproef is die ooie vir 120 dae gemelk en die melkopbrengs, melksamestelling, verandering in liggaamsgewig, voerinname en VOD bepaal en vergelyk tussen behandelings. In die verterings- en stikstofmetabolismeproef is 18 ooie gebruik om die diete te vergelyk. Verder is die diete ook vergelyk in ‘n degraderings- en deurvloeitempoproef met gekannuleerde Dohne merino hamels. Dieet-proteien-degradeerbaardheid waardes verkry uit die degradeerbaarheidsproef het aangedui dat die bepaalde RDP: NDP verhoudings was 82:18, 78:22 en 79:21 vir die lae NDP, lae prote'fen hoe NDP en hoe NDP diete, en dat daar geen verskil in dieet-prote'fen-degradeerbaardheid was tussen die drie rantsoene. Resultate van die produksieproef dui daarop dat daar verskille in voerinname, droematerialinname, en liggaamsgewig tussen die drie rantsoene was. Die ooie op die laer NDP rantsoen het ‘n hoe voer en DM inname gehad en was swaarder na 120 dae in die proef as die ooie in die ander twee behandelings. Redes vir hierdie verskille is nie as gevolg van dieet-proteiendegradeerbaarheid nie. Die smaaklikheid kon dalk ‘n rol gespeel het omdat dat die twee hoe NDP rantsoene hoer vlakke van vismeel gehad het. Daar was geen verskil in melkproduksie, melksamestelling en melkproduksiedoeltreffenheid tussen die drie behandelings. Resultate van die verteringsproef het tussen die laer NDP-rantsoen en die ander twee rantsoene gevarieer. Die rede vir die verskil in verteerbaarheid mag wees a.g.v. verskillende deurvloeitempo’s (laer NDP = 0.064/uur teenoor 0.044 - 0.045/uur vir die laeproteien en hoe-proteienrantsoene) en die ADF waarde wat van die lae NDP rantsoen verskil het van die ander twee rantsoene. Omdat die resultate van die degradeerbaarheidsproef aangedui het dat daar geen verskil in dieet-proteiendegradeerbaardheid was nie is dit nie moontlik om ‘n gevolgtrekking te maak random die invloed van dieet-proteien-degradeerbaardheid op die produksie van lakterende Saanen melkbokke nie.

The Lake Clearwater catchment, in the Canterbury high country of New Zealand, has a native ecosystem that is adapted to low nutrient conditions. Wetlands in the catchment are identified by the Department of Conservation’s Arawai Kākāriki Wetland Restoration Programme as one of three important endemic wetland types in New Zealand. Uncertainty regarding diffuse nutrient load from agriculture into the lake and wetland ecosystems is limiting effective management of the catchment. This study investigated hydrological processes and nitrogen and phosphorus concentrations to improve knowledge of the sources, characteristics and magnitude of nutrient loading from agricultural land use in this 46 km2 high country catchment. Relevant hydrological data and literature pertaining to the catchment was extensively reviewed. In addition, flow for five key surface waterways was continuously logged at ten sites for 2 years. Concurrently, nutrient concentrations for total nitrogen, nitrate, ammoniacal nitrogen, total phosphorus and dissolved reactive phosphorus were measured at ten surface water sites and three groundwater sites. Total nitrogen and phosphorus load from farmland was calculated from annual flow and median concentrations for four waterways: farmland perennial stream runoff, farmland ephemeral stream runoff, a wetland channel below the farmed hillslope and the lake outlet. Similarly, total nitrogen and phosphorus load for unfarmed land was calculated from the flow and median concentration of two un-impacted perennial streams. Total nitrogen and phosphorus mass balances were calculated and used to estimate subsurface nutrient load and runoff volume from the farmed hillslope. Estimates of subsurface runoff were also made using Darcy’s equation and a water balance. Nutrient load predictions from the Catchment Land Use for Environmental Sustainability (CLUES) model were compared to measured loads. Nutrients were found to be elevated downstream of farmland, especially nitrogen, which was often above relevant guidelines and typical concentrations in upland waterways in Canterbury. Nitrate in farmland subsurface runoff was elevated and was estimated to contribute 52% of total nitrogen yield from farmland. Total nitrogen yield (1.96-2.94 kg ha-1 year-1) for farmed land was comparable to minimum values for pastoral land use in literature but total phosphorus yield (0.093-0.123 kg ha-1 year-1) was well below published values. The range in yield estimates is due to subtraction of a high and a low estimate of natural baseline yield from the measured in-stream yield. Total nitrogen export from the lake (2518 kg year-1) was greater than estimated input (1375 kg year-1) from farmed and non-farmed land indicating an additional source of nitrogen into Lake Clearwater. Total phosphorus export from Lake Clearwater of 58 kg year-1 was 24% less than total estimated loads into the lake (76 kg year-1) from farmed and non-farmed land. Phosphorus was not often above relevant guidelines and the median total nitrogen to total phosphorus ratio in Lake Clearwater (49:1) indicated phosphorus is the limiting nutrient in the lake. Because phosphorus was less elevated relative to nitrogen, an increase in phosphorus inputs could have a greater effect on productivity in the wetland and lake. With corrected land use information, total nitrogen loads predicted by the CLUES model were reasonable but total phosphorus loads were greatly overestimated. Investigation into potential impacts of the elevated nutrient loads described in this study on receiving native ecosystems is recommended to inform conservation efforts.

3 pp. / The optimum planting by elevation is presented for small grains in Arizona. The influence of planting date on crop development, grain yield and frost risk is discussed.

No description available.

The issue of how to test and ultimately regulate tobacco products represents a critical challenge for the public health community. Although the current international testing regime for conventional cigarettes is widely acknowledged to be seriously flawed, there is a lack of data to guide potential alternatives, particularly in the area of human puffing behaviour. The current study sought to: 1) collect naturalistic measures of smoking behaviour, 2) examine the extent to which levels of tar, nicotine, and carbon monoxide from each of five testing protocols were associated with measures of nicotine uptake among smokers, and 3) examine the validity of self-report measures of smoking behaviour. These questions were examined through two different studies. First, a field study of smoking behaviour was conducted with 59 adult smokers, who used a portable device to measure smoking topography over the course of 3 one-week trials. Participants were asked to smoke their usual ?regular-yield? brand through the device for Trial 1 and again, 6 weeks later, at Trial 2. Half the subjects were then randomly assigned to smoke a ?low-yield? brand for Trial 3. The smoke intake and constituent yield of each brand was then tested under five testing protocols: ISO, Massachusetts, Canadian, a Compensatory protocol, and a Human Mimic regime. Participants also completed self-report measures of puffing behaviour at recruitment and immediately following each of the three one-week smoking trials. Several of these self-report measures were subsequently included in the Waves 2 and 3 of the International Tobacco Control Policy Evaluation (ITC) Survey?an international cohort survey of adult smokers from Canada, Australia, the US, and the UK. <br /><br /> The results of the field study indicate a high degree of stability in puffing behaviour within the same smoker over time, but considerable variability between smokers, including those smoking the same brand. Puffing behaviour was strongly associated with cotinine levels, particularly when included in an interaction term with cigarettes per day (<em>Part r</em> = . 50, <em>p</em><. 001). Smokers who were switched to a ?low-yield? cigarette increased their total smoke intake per cigarette by 40% (<em>p</em>=. 007), with no significant change in their in salivary cotinine levels. <br /><br /> The results indicate systematic differences between human puffing behaviour and the puffing regimes used by machine testing protocols. The puffing behaviour observed among participants during the one-week smoking trials was significantly more intense than the puffing parameters of the ISO and Compensatory testing regimes. When cigarette brands were machine tested using participants? actual puffing behaviour, the results suggest that participants ingested two to four times the level of tar, nicotine, and carbon monoxide indicated by the ISO regime, and twice the amounts generated by the Compensatory regime for ?regular-yield? brands. The Canadian and Massachusetts regimes produced yields much closer to the ?Human Mimic? yields, although nowhere near a maximum or intense standard, as they were designed to do. Only the nicotine yields from the Human Mimic regime were correlated with measures of nicotine uptake among smokers, and only moderately so (<em>Part r</em> = . 31, <em>p</em>=. 02). <br /><br /> Self-report measures of puffing behaviour collected during the field study were moderately correlated with physiological measures of puffing and exposure. Self-report measures of puff depth and puff number showed some promise as predictors of salivary cotinine, although the results are characterized by inconsistencies across models. The self-report measures included in the ITC survey were only weakly associated with age and cigarettes per day, with modest between-country differences. <br /><br /> Overall, this research highlights the importance of puffing behaviour as a determinant of smoke exposure, and provides strong evidence of compensatory smoking for ?low-yield? brands. The findings also highlight the variability in human smoking behaviour and the limitations associated with machine testing protocols. Perhaps most important, the findings underscore the immediate need to revise the ISO protocol, which systematically underestimates smoking behaviour among humans and exaggerates differences between cigarette brands.