Estimating amino acid limitations in California dairy rations and the effect of feeding a ruminally protected lysine supplement on animal performance

The widespread increase in use of maize-based feedstuffs in California dairy cow rations has raised concerns of reduced efficiency of CP utilization due to the low lysine content of maize and maize by-products. The objectives of this research were to determine the impact of increased dietary maize CP levels on animal performance using three metabolic models of dairy cows in order to predict limiting AA’s in California dairy rations to identify a ruminally protected AA package to supplement similar rations. Since lysine was the most consistently predicted limiting AA among dairies, and metabolic models, the dairy with the ration calculated to be the most limiting in lysine was chosen to determine effects of feeding an RPL product on milk production and composition, as well as on N balance. Nutrient profiles of 16 high multiparity cow rations were evaluated and limiting AA predicted by the metabolic models Amino Cow, CPM Dairy and Shield. Higher inclusion levels of maize products in rations increased the contribution of maize CP to the total CP content of the TMR, to between 20 – 40%, but had no impact on cow performance. Even though the lysine to methionine ratio decreased as more maize CP was included in the TMR, it did not have a major impact on the final predicted AA profile of MP, or milk component levels, but, according to Shield, it had an effect on milk yield. Methionine, isoleucine and lysine were predicted to be most limiting according to Amino Cow, CPM Dairy and Shield respectively. The models suggested three dramatically different AA packages but the high degree of consistency within model in predicting the limiting AA sequence among dairies, suggest that there may be sufficient consistency in the nutrient profiles among rations to support production of a ruminally protected AA complex. The second experiment used a double (i.e., early and mid-lactation multiparity dairy cows) 2 x 2 factorial with 28 day experimental periods. Feeding the RPL, with estimated rumen escape of lysine between 18 and 23% suggesting an increased intestinal absorption of lysine between 8 and 22 g/d/cow, did not influence DMI or milk, true protein and lactose yields. Milk fat yield and concentration decreased, while MUN percentages increased when RPL was fed. Blood plasma levels of almost all AA’s, except lysine, decreased when RPL was fed, suggesting that lysine was the limiting AA and that its supplementation led to increased absorption and utilization of other AA. The lack of response in milk protein synthesis and the decrease in plasma 3-MH concentrations when RPL was fed suggests that muscle protein synthesis was stimulated, and degradation reduced, with RPL feeding. It is possible that lysine had an effect, either directly or indirectly, on muscle protein turnover and energy metabolism that, impacted intakes, metabolism and absorption of AA and milk production in mid lactation cows, but it had no major impact on early lactation cows. CopyrightDissertation (MSc(Agric))--University of Pretoria, 2009.Animal and Wildlife Sciencesunrestricte

Teacher perspectives and practices in teaching English reading comprehension to Grade 2 First Additional Language Learners

English reading comprehension is an educational challenge worldwide, and South Africa is no exception. English as First Additional Language (FAL) is very significant in South Africa. Learners require specialised support by teachers to overcome the language barrier and comprehend what they read in English as their first additional language. This aspect of overcoming the language barrier in EFAL lead to the study which was conducted to investigate the teacher perspectives and practices in teaching English reading comprehension to Grade 2 First Additional Language Learners. This qualitative study was undertaken through the interpretive paradigm and a case study research design was used. The research sites included three independent English schools in the Gauteng Province, South Africa. The data collection strategies included individual semi-structured interviews and classroom observations of the teachers teaching English reading comprehension. In addition, a reflective journal was kept by the researcher to document the participants’ body language during the interviews and observations. The data were analysed by making use of thematic coding. Findings revealed the pre-comprehension strategies, classroom practices, resources used in teaching English reading comprehension and ways to make reading fun that teachers use to teach English reading comprehension to Grade 2 FAL learners. These strategies and practices are discussed in light of the various stages of the reading process – as reflected in a reading comprehension teaching framework. Teachers can use this framework to address the key challenges in teaching FAL learners.Keywords: reading comprehension, teaching framework, scaffolding, teacher perspectives, First Additional Language

Collaborative conversations with teachers about hope : during and after Covid-19

The concept of hope, from both a secular and Christian perspective, has been debated in many disciplines for centuries. Ideas around the phenomenon of hope have recently expanded in the field of education, owing to the major changes and challenges teachers had to face during the COVID-19 pandemic. Contemplating the concept of the source or existence of hope, especially during challenging times, requires careful investigation into how people interpret and experience hope. Therefore, this qualitative study focuses on teachers’ interpretations and experiences of hope during and after the COVID-19 pandemic. This study was conducted through two collaborative conversations held with teachers as part of a community engagement project stretching across the duration of the COVID-19 pandemic. Deductive data analysis was done through ATLAS.ti. The findings revealed that the teachers had a similar understanding of hope. Furthermore, it was also found that hope cannot be described solely from a secular or Christian perspective. However, the participants’ beliefs regarding the source of hope differed. These beliefs provided insight into whether participants’ understanding of hope was based on a secular or Christian perspective. From a secular perspective, hope was understood from the hope theory of Snyder et al. (1991). According to this theory, hope results from pathways thinking (planning various routes to a given goal), agency to reach a goal, and goal setting. In contrast, from a Christian perspective, hope views God as the source of hope owing to his promises. The invisible force of hope, whether agency-based or faith-based, was found to be central to teacher agency; therefore, the term “faith-based, purpose-driven hope” emerged from the data. Recommendations are made regarding the importance of nurturing teachers’ hope to improve educational outcomes.Daar is al eeue lank in baie dissiplines oor hoop as konsep, uit ‘n sekulêre sowel as ‘n Christelike perspektief, gedebatteer. Idees oor hoop as verskynsel het onlangs in die onderwysveld toegeneem weens die groot veranderinge en uitdagings wat onderwysers gedurende die Covid-19-pandemie moes trotseer. Besinning oor die bron of bestaan van hoop as konsep, veral in uitdagende tye, vereis ‘n noukeurige ondersoek na hoe mense hoop vertolk en beleef. Daarom is hierdie kwalitatiewe studie toegespits op onderwysers se interpretasies en belewings van hoop tydens en ná die Covid-19-pandemie. Hierdie studie is uitgevoer deur middel van twee samewerkende gesprekke met onderwysers as deel van ‘n gemeenskapsbetrokkenheidsprojek wat oor die duur van die Covid-19-pandemie gestrek het. Deduktiewe dataontleding is met behulp van ATLAS.ti gedoen. Die bevindinge het aan die lig gebring dat die onderwysers ‘n soortgelyke begrip van hoop gehad het. Voorts is daar ook bevind dat hoop nie slegs vanuit óf ‘n sekulêre óf ‘n Christelike perspektief beskryf kan word nie. Die deelnemers se oortuigings aangaande die bron van hoop het egter verskil. Hierdie oortuigings het insig gebied in die vraag of die deelnemers se begrip van hoop op ‘n sekulêre of Christelike perspektief gebaseer was. Vanuit ‘n sekulêre perspektief is hoop vanuit die hoopteorie van Snyder et al. (1991) verstaan. Volgens hierdie teorie spruit hoop uit sogenaamde roetedenke (om ‘n verskeidenheid roetes na ‘n gegewe doelwit te beplan), werksaamheid/agentskap om ‘n doelwit te bereik en doelwitstelling. Daarteenoor word God vanuit ‘n Christelike perspektief as die bron van hoop beskou weens sy beloftes. Daar is gevind dat hoop se onsigbare krag, hetsy dit op werksaamheid/agentskap of geloof gebaseer is, sentraal tot onderwyserswerksaamheid/onderwysersagentskap staan; daarom het die term “geloofsgebaseerde, doelgedrewe hoop” uit die data te voorskyn gekom. Aanbevelings word gemaak oor die belangrikheid van die koestering en versterking van die hoop wat onderwysers het om opvoedkundige uitkomste te verbeter.http://www.koersjournal.org.zahj2024Early Childhood EducationSDG-04:Quality Educatio

Effects of ruminally protected methionine and/or phenylalanine on performance of high producing Holstein cows fed rations with very high levels of canola meal

Canola meal is the second largest protein feed in the Northern latitudes and inclusion levels in dairy rations are expected to increase due to projected large increases in production of canola seed in Canada. However, a recent study (Swanepoel et al. 2014) showed that even though higher inclusions of canola meal (CM) had a positive effect on production when CM directly substituted for high protein corn based dried distillers grains (DDG), that there was an optimum point at 120 to 135 g/kg of diet dry matter (DM) after which animal performance seemed to decline. Only the amino acids (AA), methionine (Met), phenylalanine (Phe) and leucine (Leu) could have limited production based upon plasma AA concentrations at the highest CM inclusion level. Our objective was to determine if either Met or Phe, or both, was limiting performance of early lactation dairy cows fed a ration containing 180 g/kg of diet DM as CM, by supplementing a calculated target of 7.5 g of intestinally absorbable Phe/cow/d and/or 8.0 g of intestinally absorbable Met/cow/d in ruminally protected (RP) forms to four pens of ~320 early lactation cows/pen in a 4 x 4 Latin square with 28 d experimental periods. Dry matter intake was not affected (avg: 27.6 +/- 0.4 kg/d) by feeding either of the RP AA, or the combination. Phenylalanine supplementation alone had no effect on milk production or composition, and body condition score (BCS) change compared to Control. Supplemental Met alone modestly increased (P<0.01) milk protein and fat content, while decreasing (P<0.01) milk lactose content and yield, but with no impact on BCS change compared to Control. Combination Met and Phe supplementation decreased milk and lactose yields, as well as lactose content (P<0.01), while increasing milk protein content and the BCS change (P<0.01). Urine volume (avg: 16.7 +/- 0.31 L/d) and flow of microbial protein (MCP) from the rumen (avg: 2092 +/- 52.7 g CP/d) were not affected by any treatment. Plasma Met levels increased (P<0.01) with both Met treatments and plasma tryptophan (Trp) levels decreased (P<0.01) with both Phe treatments. However, plasma Phe levels did not change with any treatment. Results are interpreted to suggest that delivery of Met with RP Met feeding was higher than animal requirements and caused an oversupply of Met. Addition of Phe to the Met supplementation changed the way energy was utilized by the cows, redirecting energy liberated by Met from milk components toward BCS gain. It remains unclear if Phe was limiting in the Control ration or if RP Phe was not fed at high enough levels to have a measurable response on production. However, it is clear that AA limitations, requirements and production responses are governed by much more than plasma AA levels. Results further suggest that AA are bioactive metabolites to the extent that they can change animal performance, even when they are not „limiting‟ per se, and that their supplementation to practical dairy cattle diets should be approached with extreme caution for this reason. Keywords: Spot urine purine; Estimated microbial flow; Plasma amino acids; Protein feeding. Abbreviations: AA, amino acid; ADF, acid detergent fiber; ADICP, AD insoluble CP; ADIN, acid detergent insoluble N; AL, allantoin; aNDF, amylase-treated NDF; aNDFom, aNDF free of residual ash; BCS, body condition score; BCAA, branched-chain AA; BW, body weight; CM, canola meal; CP, crude protein; CR, creatinine; DC305, DairyComp 305 management system; DDG, dried distillers grains; DHIA, Dairy Herd Improvement Association; DIM, days in milk; DM, dry matter; MCP, microbial CP; NDF, neutral detergent fiber; NEL, net energy for lactation; OM, organic matter; PD, purine derivatives; RDP, rumen degradable CP; RP, rumen protected; SCC, somatic cell count; SG, specific gravity; TMR, total mixed ration; TP, true protein.http://www.elsevier.com/locate/anifeedsci2016-07-31hb2016Animal and Wildlife Science

Impacts of adding ruminally protected phenylalanine to rations containing high levels of canola meal on performance of high producing Holstein cows

Even though studies supplementing Phe to dairy cattle are rare, it has been identified as limiting in corn silage based rations, after Lys and Met, as well as being important to the mammary gland for overall milk production. Since canola meal (CM) is low in Phe, plasma Phe concentrations decrease as more CM is included in dairy rations. A previous study fed 7.5 g/cow/day of intestinally absorbable Phe, but results suggested that it was insufficient to support increased milk production since it was primarily used to support increased body condition score (BCS; Swanepoel et al., 2015). Our objective was to determine if supplementing 15 g/cow/day of intestinally absorbable Phe in a ruminally protected (RP) form (HCMP) to a ration containing 170 g/kg CM (HCM) would support increased milk production after fulfilling its apparent 1st priority of restoring previously mobilized peptides to muscle protein synthesis, thereby regaining animal performance possibly lost with higher dietary CM inclusion levels (i.e., 130 g/kg (LCM) to 165 g/kg (HCM)) based upon Swanepoel et al. (2015). Ruminally protected Met (2.0 g/cow/day intestinally absorbable) was added as part of the treatment ration to HCM treatments to avoid a possible Met limitation. The experimental design was a 3 x 3 Latin square using 3 pens of ~315 early lactation cows/pen with three 21 day periods. Dry matter (DM) intake was not affected (avg: 27.5 ± 0.5 kg/day) by feeding RP Phe and there was no impact of treatment on milk and component yields, except a reduced lactose content (P=0.02) with Phe addition. Even though plasma Phe levels only differed numerically between treatments, its supplementation resulted in energy being diverted towards BCS gain as in Swanepoel et al. (2015), but not at the expense of milk components, suggesting that higher Phe supplementation supplied enough Phe to replace mobilized muscle protein while maintaining milk production. The lack in change of plasma Phe concentrations could be due to extensive catabolization by the liver or hepatic conversion of Phe to Tyr, which is supported by the change in plasma Tyr concentrations. Interestingly, addition of Phe to the HCM ration increased whole tract neutral- and acid detergent fiber digestibility. Perhaps Phe released into the rumen when Phe was fed stimulated fibrolytic bacteria through a direct impact on microbes of free Phe, which has previously been shown to enhance growth and/or capabilities of cellulolytic bacteria. Total net energy output decreased with HCM feeding, but was restored to the level of the LCM ration for the HCMP treatment suggesting that further investigation to determine if an even higher Phe supplementation level may have additional benefits on milk production may have merit.http://www.elsevier.com/locate/anifeedsci2017-06-30hb2016Animal and Wildlife Science

Determining the optimal ratio of canola meal and high protein dried distillers grain protein in diets of high producing Holstein dairy cows

Use of canola meal (CM) and dried corn distillers grains with solubles (DDGS) as major supplemental protein sources are common practice in North American dairy rations and usage of both is projected to increase in the future. Since limited data is available on performance of cows fed diets with different ratios of CM and DDGS, our objective was to determine the optimal ratio of CM to DDGS protein in a contemporary lactation dairy ration by feeding combinations of CM and high protein DDG (HPDDG) to early lactation multiparity dairy cows. The experiment was a 4×4 Latin square with 28 d periods using four pens of ∼320 high producing cows/pen. Treatments were created by varying the amounts of CM and HPDDG added on a DM basis to be: (1) 0 g/kg CM and 200 g/kg HPDDG, (2) 65 g/kg CM and 135 g/kg HPDDG, (3) 135 g/kg CM and 65 g/kg HPDDG, (4) 200 g/kg CM and 0 g/kg HPDDG. Dry matter intake was not affected by the CM/HPDDG ratio in the ration. Milk and lactose yield, true protein (TP) content and yield, milk fat yield as well as milk energy output increased at a decreasing rate with a higher CM/HPDDG ratio. Maximum values for milk and TP yield were at ∼135 g/kg CM, while lactose, TP content and milk energy were maximized at ∼120 g/kg CM inclusion. Milk fat content and milk energy density decreased linearly with higher CM inclusion. Body condition score change responded quadratically with the highest gain at ∼120 g/kg CM inclusion. The purine derivative to creatinine index increased linearly with higher CM inclusion levels, suggesting that microbial protein production (MCP) was limited in the 0 g/kg CM ration and was progressively stimulated by higher feeding levels of CM. Plasma AA levels suggest that the reduction in lysine in dietary protein, together with the decrease in MCP production, resulted in a substantial reduction in lysine available for milk production, thereby limiting performance in the higher HPDDG ration. The only AA which decreased in plasma with higher CM feeding levels were phenylalanine, leucine and methionine. That the level of leucine in the plasma was still decreasing linearly, while methionine and phenylalanine responded quadratically at the 200 g/kg CM treatment, was interpreted to suggest that the leucine supply remained higher than its requirement at the highest CM inclusion level, but that phenylalanine and/or methionine was limiting production in the highest CM ration. Overall, results suggest that the optimum ratio of CM to HPDDG in these diets was with 120–135 g/kg of diet DM from CM.http://www.elsevier.com/locate/anifeedscihj201

Rumen microbial protein flow and plasma amino acid concentrations in early lactation multiparity Holstein cows fed commercial rations, and some relationships with dietary nutrients

Common contemporary diet formulation methods involve factorial or empirical models which simulate ruminal fermentation and post ruminal absorption to predict nutrient supply and needs. However, due to their inability to encompass all animal factors that affect digestion and absorption, metabolic models inadequately predict microbial protein (MCP) synthesis in the rumen and passage of nutrients such as protein and amino acids (AA) to the small intestine. Practical and simple on-farm methods to obtain “real time” values directly from cows are required to establish normal ranges of MCP flow from the rumen and plasma AA concentrations on commercial dairy farms. Urine purine derivative (PD) output, an index of MCP supply to the intestine when analyzed in spot urine samples, can accurately predict MCP flow from the rumen under farm conditions. Blood sampling from the tail vein is easily performed on commercial dairy farms and concentrations of free AA in these plasma samples, representative of intestinally absorbed AA, can be used as an index to predict limiting AA. A group of 20 commercial dairy farms, milking 2677 + 372 cows either 2 or 3 times a day were selected and one of their early lactation pens holding 255 + 20 cows were used to represent the range of nutritional strategies and rations fed to California dairy cows. On the day of sampling, one load of early lactation total mixed ration (TMR) was sampled and 20 pre-selected cows were body condition scored (BCS). Directly after scoring, the 4 cows with the highest, and the 4 cows with the lowest BCS values were removed to collect 12 tail vein blood samples from the group with average BCS scores. Spot urine samples were collected from all voluntarily urinating cows (retaining 6 to 12 samples/pen to match the characteristics of the cows pre-selected for BCS scoring and blood sampling). Most rations contained alfalfa hay, corn silage, almond hulls, corn dried distillers grains, corn grain, cottonseed, canola meal (solvent) and a mineral premix. Selected cow groups produced 45 ± 1.2 kg milk/day at 73 ± 0.5 days in milk with a BCS of 2.6 + 0.04 at 2.8 lactations. There were no correlations between MCP and milk production, but MCP flow from the rumen was correlated to organic matter and neutral detergent fiber content of the TMR (P<0.01 and P=0.03 respectively). Plasma AA concentrations were correlated with rumen undegradable crude protein (CP) and starch content of the TMR, with many inter-correlations among AA, but no plasma AA concentration was correlated to milk production. Results show that 8 urine samples and 6 blood samples/group provided accurate representation of the group. This study documents ranges of MCP flowing from the rumen (1703 ± 54.6 g CP/day), and plasma AA levels (with low variation within AA), in early lactation multiparity Holstein cows fed a range of contemporary dairy rations with multiple ingredient profile combinations. Since farms selected were well managed operations with cow groups selected to represent averages in early lactation, this data can be used as a benchmark for high, low and mean levels of MCP flow, and plasma AA concentrations, as well as provide real time evaluation of rations to identify possible rumen microbial growth and/or absorbable AA issues in commercial dairy cows.http://www.elsevier.com/locate/livsci2017-08-31hb2016Animal and Wildlife Science

Teacher perspectives and practices in teaching English reading comprehension to Grade 2 First Additional Language Learners

English reading comprehension is an educational challenge worldwide, and South Africa is no exception. English as First Additional Language (FAL) is very significant in South Africa. Learners require specialised support by teachers to overcome the language barrier and comprehend what they read in English as their first additional language. This aspect of overcoming the language barrier in EFAL lead to the study which was conducted to investigate the teacher perspectives and practices in teaching English reading comprehension to Grade 2 First Additional Language Learners. This qualitative study was undertaken through the interpretive paradigm and a case study research design was used. The research sites included three independent English schools in the Gauteng Province, South Africa. The data collection strategies included individual semi-structured interviews and classroom observations of the teachers teaching English reading comprehension. In addition, a reflective journal was kept by the researcher to document the participants’ body language during the interviews and observations. The data were analysed by making use of thematic coding. Findings revealed the pre-comprehension strategies, classroom practices, resources used in teaching English reading comprehension and ways to make reading fun that teachers use to teach English reading comprehension to Grade 2 FAL learners. These strategies and practices are discussed in light of the various stages of the reading process – as reflected in a reading comprehension teaching framework. Teachers can use this framework to address the key challenges in teaching FAL learners.http://www.ajol.info/index.php/jltam2021Early Childhood Educatio

Nomenclature- and Database-Compatible Names for the Two Ebola Virus Variants that Emerged in Guinea and the Democratic Republic of the Congo in 2014

In 2014, Ebola virus (EBOV) was identified as the etiological agent of a large and still expanding outbreak of Ebola virus disease (EVD) in West Africa and a much more confined EVD outbreak in Middle Africa. Epidemiological and evolutionary analyses confirmed that all cases of both outbreaks are connected to a single introduction each of EBOV into human populations and that both outbreaks are not directly connected. Coding-complete genomic sequence analyses of isolates revealed that the two outbreaks were caused by two novel EBOV variants, and initial clinical observations suggest that neither of them should be considered strains. Here we present consensus decisions on naming for both variants (West Africa: “Makona”, Middle Africa: “Lomela”) and provide database-compatible full, shortened, and abbreviated names that are in line with recently established filovirus sub-species nomenclatures

Effect of rumen protected amino acid supplementation on performance of Holstein cows fed rations containing high levels of canola meal

As supplies of canola meal (CM) and dried distiller s grains (DDGS) increase, so does the incentive to use these feeds as protein supplements at higher inclusion levels in dairy cattle rations. However, this could have detrimental effects on animal production due to imbalances of amino acids (AA) or dietary rumen degradable protein (RDP) vs. rumen undegradable protein (RUP) ratios. Few studies have been completed comparing performance of dairy cattle fed CM and DDGS, and little information is available on inclusion levels higher than 120 g/kg dry matter (DM) for either protein source. Overall project objectives were to (1) determine the highest level at which CM and the high protein, low fat DDGS (HPDDG) alternative can be included in dairy rations before adversely affecting production, (2) identify nutritional limitations at high inclusion levels of CM, and (3) identify resolutions for the limitations associated with feeding very high levels of CM to high producing dairy cows. Treatments in Experiment 1 were created by varying ration inclusion levels of CM and HPDDG: (1) 0 g CM/kg and 200 g HPDDG/kg, (2) 65 g CM/kg and 135 g HPDDG/kg, (3) 135 g CM/kg and 65 g HPDDG/kg, (4) 200 g CM/kg and 0 g HPDDG/kg TMR DM. Results suggest that the optimum level of CM in the ration was in the range of 120 to 135 g/kg DM, and Met and Phe were identified as limiting AA. In Experiment 2 these AA were supplemented in a ruminally protected (RP) form, either alone or in combination, to a Control ration containing 200 g CM/kg DM. Compared to Control, supplemental Met shifted milk energy amongst milk components without affecting milk energy output. Phe alone had no effect on animal performance, but adding it in combination with Met diverted energy away from milk components towards body condition score (BCS) gain. While results suggest that neither Met nor Phe was a limiting AA in this experiment, at least in a classical sense, results suggest that both were metabolically bioactive. Experiment 3 used multiparity cows fed a wide range of contemporary early lactation dairy rations in California (USA), employing sampling practices easily performed on a routine basis on commercial dairy farms, in order to (a) determine normal ranges of microbial crude protein (MCP) flowing from the rumen, and plasma AA concentrations, in early lactation multiparity Holstein cows, to (b) benchmark their high, low and mean levels using sampling methods possible under commercial conditions in order to assist in evaluation of commercial rations formulated with or without the aid of metabolic models, and to (c) create a reference database to help interpret the biological meaning of treatment concentrations of these parameters under commercial and experimental conditions. Since relationships between milk production, total mixed ration (TMR) ingredient profiles and plasma AA concentrations from Experiment 3 confirmed the hypothesis that Phe is important relative to milk production, Experiment 4 was designed to determine if supplementing higher levels of RP Phe would enhance performance of early lactation dairy cows by supplying enough Phe to support increased milk production, after fulfilling its apparent 1st priority of restoring previously mobilized peptides to muscle protein. Indeed this was confirmed since increased Phe supplementation regained the animal energy output lost when CM inclusion was increased above the optimal level.Thesis (PhD)--University of Pretoria, 2016.Animal and Wildlife SciencesPhDUnrestricte