81 |
Effect of live yeast supplementation on performance parameters of Jersey cows grazing ryegrass/kikuyu pastureCoetzee, Carmen 17 November 2011 (has links)
Energy is the first-limiting nutrient for cows grazing pasture therefore, energy supplementation is necessary for high producing animals. In pasture-based systems, the concentrate is fed twice a day in the dairy parlour during the milking procedure. Consumption of large amounts of fermentable carbohydrates results in a drop in rumen pH and this may induce rumen acidosis. This may lead to reduced intake, lower fibre digestion and depressed milk yield. Supplemental yeast offer great possibilities in stabilising the rumen fermentation patterns and, therefore, improving dry matter intakes (DMI). This may increase milk production, milk composition parameters, rumen volatile fatty acid concentrations (VFA) which leads to higher profits. Investigating these responses, a trial was conducted, where live yeast (Levucell SC 10 ME-Titan) was supplemented to Jersey cows grazing ryegrass/kikuyu pastures, supplemented with 6 kg (as is) dairy concentrate per day split over two milking periods. Thirty multiparous high-producing Jersey cows between 30 and 120 days in milk (DIM) were selected, blocked and randomly allocated to control (no yeast) or live yeast treatment groups. Ten fistulated lactating cows were added in a cross-over design (two periods and two treatments) and all 40 cows strip grazed Italian ryegrass (Lollium multiflorum) and kikuyu pastures as one group. A new pasture strip was allocated after each milking and pasture was measured using a rising plate meter (RPM). The yeast product Levucell SC 10 ME – Titan containing Saccharomyces cerevisiae CNCM I-1077 was supplied by Lallemand S.A.S (19 rue des Briquetiers, 31702 Blagnac cedex, France). The Levucell SC 10 ME – Titan is a micro-encapsulated formulation for premix and pelleted feeds. The yeast treatment group had the yeast pelleted in with the dairy concentrate at a concentration of 167 g of yeast per ton of concentrate, to obtain the required intake of 1 g yeast per cow per day as specified by Lallemand. Milk yields were recorded daily and composite milk samples were taken every two weeks to determine, milk fat, protein, lactose, milk urea nitrogen (MUN) and somatic cell count (SCC) contents. The fistulated cows were adapted to their respective diets and treatments for 21 days after which the pH measurment, rumen fluid sampling, and In sacco study were conducted. Milk yield, 4% fat corrected milk (FCM) yield, milk protein and lactose percentages, SCC, body condition score (BCS), and live weight did not differ (P > 0.05) between treatments. The milk fat% however, was higher for the yeast supplemented cows at 4.24% compared to the control group of cows of 3.99% (P < 0.05). The mean acetic and total VFA concentration (mmol/L) for the control treatment was higher compared to the yeast treatment (P < 0.05). There was no difference in the fermentation patterns of VFA, the pH and NH3-N values measured between treatments (P > 0.05). The mean In sacco neutral detergent fibre (NDF), organic matter (OM) and DM disappearance was higher for the yeast treatment group of cows after a 12 and 24 hour incubation compared to the control group (P < 0.05). The mean ruminal NDF disappearance of ryegrass in cows supplemented with yeast increased by 11.9% and 6.3% compared to the control at the 12 and 24 hour incubation periods, respectively. With higher fibre digestibilities in the rumen and more acetate available at the mammary gland and subsequently higher milk fat percentages, the yeast effects on stimulating the cellulolytic bacteria in the rumen, may be a possible explanation for the results in the current study and it is well documented in previous studies. Live yeast supplementation resulted in higher milk fat percentages which improved milk price. / Dissertation (MSc(Agric))--University of Pretoria, 2011. / Animal and Wildlife Sciences / unrestricted
|
82 |
Replacing maize with barley in concetrates fed to jersey cows grazing on kikuyu/ryegrass pastureLehmann, Maryna January 2004 (has links)
The aim of the first study was to determine if barley could replace maize as an energy source in concentrates fed to dairy cows grazing on kikuyu/ryegrass pasture without affecting the milk production, milk composition, or cause metabolic disorders. Sixty Jersey cows, in early to mid lactation were randomly allocated to one of five treatments (n = 12) based on feeding concentrates with different ratios of maize to barley, ranging from 100:0, 75:25, 50:50, 25:75 and 0:100, respectively. Concentrates contained 12 MJ ME kg -1 and 130g CP kg-1 DM and cows were fed 3 kg (as-is) concentrate after each milking for a period of 42 days (14-day adaptation and 28-day measurement). Cows strip-grazed the irrigated kikuyu/ryegrass pastures (15.7 ± 1.8 percent DM; 20.2 ± 4.3 percent CP; 44.7 ± 3.5 percent NDF). Milk weights were recorded daily and milk samples collected weekly and analyzed for milk fat and protein content. Body condition score and live weight were recorded at the start and end of the experimental period. Data of all the studies were subjected to a one-way ANOVA. Daily milk yield, FCM, MUN, milk fat yield, milk fat percent, protein yield, protein percent, live weight change, or body condition score change were not affected by treatment and values were 15.8 kg, 17.2 kg, 14.9 mg dl-1, 0.72 kg, 4.56 percent, 0.59 kg, 3.77 percent, 6.67 kg, and 0.15 BCS; 15.6 kg, 17.4 kg, 15.2 mg dl-1, 0.73 kg, 4.3 percent, 0.57 kg, 3.71 percent, 1.33 kg and 0.04 BCS; 17.2 kg, 17.9 kg, 15.2 mg dl-1, 0.74 kg, 4.36 percent, 0.63 kg, 3.71 percent, 0.33 kg and 0.08 BCS; 15.6 kg, 16.4 kg, 15.5 mg dl-1, 0.67 kg, 4.33 percent, 0.60 kg, 3.83 percent, -1.46 kg and 0.11 BCS; and 15.0 kg, 16.0 kg, 15.5 mg dl-1, 0.67 kg, 4.57 percent, 0.57 kg, 3.85 percent, 8.86 kg, and 0.05 BCS, respectively for the cows fed 100:0, 75:25, 50:50, 25:75 and 0:100 maize to barley ratio concentrate. According to these results, barley can replace maize without significantly affecting the milk production or milk composition. None of the cows presented any visible symptoms of acidosis. As it was clear from the results in the first study that maize could replace barley the aim of study 2A was therefore focused on determining the effect of feeding different levels of such a barley-based (2.4, 4.8 or 7.2 kg cow-1day-1) concentrate, on milk production, milk composition and live weight change of Jersey cows on kikuyu/ryegrass pasture (23.1 ± 2.95 percent DM, 11.1 ± 0.11 percent CP, 60.8 ± 0.58 percent NDF). Forty-five Jersey cows (early- to mid lactation), were randomly allocated to one of three treatments (n = 15) involving different levels of concentrate (12 MJ ME and 130g CP kg-1 DM) feeding for a period of 42 days (14-day adaptation and 28-day measurement). Milk weights were also recorded daily, and milk samples collected weekly, and analyzed for milk fat and protein. Body condition score and live weight were recorded at the start and end of the experimental period. The results of this study indicated that increasing the concentrate level from 2.4 to 4.8 and 7.2kg cow-1day-1 did not increase the milk yield (14.0 kg, 15.2 kg, 14.4 kg; P = 0.19). The FCM production increased from 15.8 to 17.5kg (P = 0.04) as the concentrate level increased from 2.4 to 4.8kg cow-1day-1. Increasing the concentrate from 4.8 to 7.2kg cow-1day-1 did not result in a significant increase in FCM. The milk protein percent increased significantly from 3.4 - 3.6 percent when the concentrate feeding level was increased from 2.4 to 7.2kg cow-1day-1. The MUN levels were 17.09 mg dl-1, 16.03 5 mg dl-1, and 16.36 mg dl-1 for the 2.4, 4.8 and 7.2kg cow-1day-1 concentrate levels, respectively. This is well within the recommended MUN levels (12 – 18 mg dl-1) indicating that sufficient protein was fed to cows. Increasing the concentrate level from 4.8 to 7.2 kg cow-1day-1 did not increase production, probably due to a higher pasture substitution rate. Supplementing large quantities of rapidly fermentable grains, such as barley, can suppress rumen pH and may have a negative effect on the rate and extent of fibre digestion in the rumen. Therefore the aim of study 2B was not only to determine the effect of feeding different levels of a barley-based concentrate, on milk production, milk composition and live weight change, but was also to determine the effect of a low (4.8 kg cow-1day-1) versus a high (7.2 kg cow-1day-1) level of barley-based concentrate supplementation on ruminal DM and NDF degradability of Westerworld ryegrass sampled from the pastures that these cows were grazing on. Sixty Jersey cows (early- to mid lactation), were randomly allocated to one of three treatments (n = 20) involving different levels of concentrate feeding. Concentrate (12 MJ ME, 130g CP kg-1 DM) was fed at 2.4, 4.8 or 7.2 kg cow-1day-1 for a period of 74 days (14-day adaptation and 60-day measurement). These cows stripgrazed irrigated kikuyu/ryegrass pastures (14.7 ± 4.37 percent DM, 25.1 ± 1.53 percent CP, and 44.4 ± 2.58 percent NDF) at a daily pasture allocation of 10 kg DM cow-1. Milk weights were recorded daily and milk samples collected weekly and analyzed for milk fat and protein. Body condition score and live weight were recorded at the start and end of the experimental period. Twelve Jersey cows, fitted with ruminal cannulae, were randomly allocated to two of the three treatments in the production study and received either 2.4 or 7.2 kg cow-1 day-1, of the same barley-based concentrate, in a two-period crossover design. These cows strip-grazed the same irrigated kikuyu/ryegrass pastures as the sixty cows in the production study. Each period consisted of 21 days for adaptation and seven days for data collection. Rumen liquor samples were collected every 4 hours within a 24-hour cycle and repeated once. Rumen pH was measured immediately, recorded, and the supernatant fluid preserved and frozen, pending VFA analysis. The in situ nylon bag technique was used to determine DM and NDF degradation and dried samples of Westerworld ryegrass pasture were incubated for 0, 4, 8, 12, 20, 30, 48, 72 and 96 hours. The data were fitted in the non-linear model p = a + b (1-exp-ct) (Ørskov & McDonald, 1979). Daily milk production, fat corrected milk, milk fat yield and milk fat percent were not affected by treatment and values were 17.3 kg, 18.4 kg, 0.76 kg and 4.42 percent; 19.0 kg, 20.0 kg, 0.82 kg and 4.35 percent; and 18.1 kg, 19.1 kg, 0.79 kg and 4.37 percent for the 2.4, 4.8 and 7.2 kg cow-1 day-1 concentrate treatments, respectively. Milk protein percentage of cows on the 7.2 kg concentrate cow-1 day-1 was significantly higher than that of cows on 4.2 kg concentrate cow-1 day-1 feeding level. Live weight increased significantly as the level of concentrate feeding increased and values were 17.9 kg; and 28.9 kg on the 2.4 and 7.2kg concentrate treatment, respectively. There was a significant increase in the live weight of cows that were fed 7.2 kg cow-1 day-1 (as-is) in comparison to those cows that were fed 2.4 kg concentrate cow-1 day-1 (as-is). This may have resulted from more nutrients being partitioned to live weight gain rather than milk production. No further response in milk production was observed when concentrate daily feeding was increased from 4.8 to 7.2 kg cow-1 day-1. It is postulated that the higher concentrate allowance resulted in a higher substitution rate and lower DMI intake from pasture. 6 There was no significant decline in the rumen pH (6.2 ± 0.4 and 6.2 ± 0.5) when the concentrate level was increased from 2.4 to 7.2 kg cow-1 day-1 (as-is). The total VFA (118.1 ± 45.9 and 139.4 ± 45.6 mmol L-1) and isovalerate (0.009 ± 0.07 and 0.248 ± 0.52 mmol L-1) increased significantly when the concentrate was increased from 2.4 to 7.2 kg cow-1day-1. No other rumen parameters were affected by treatment. Ruminal DM and NDF degradability of the Kikuyu/ryegrass pature were not affected by the level of concentrate supplementation. An increase in the concentrate level from 2.4 to 7.2 kg cow-1day-1 did not reduce degradability of either DM (94.67 ± 5.97, 94.49 ± 5.09; P = 0.919) or NDF (92.15 ± 8.69, 94.4 ± 11.73; P = 0.451), respectively. Results of rumen parameters and PD values were within the range reported by Bargo et al., (2003), viz. pH 5.76 – 6.29, NH3-N concentration 8.7 – 32.2 mg dl-1, total VFA concentration 90.3 - 151.4 mmol L-1 and PD values 89.5 – 93.5 % reported by Bargo et al. (2003). According to these authors, there is no simple relationship between any amount of the concentrate supplemented, and the ruminal pH and concentrate feeding only affects the in situ ruminal digestion of pasture when it is fed, at quantities higher than 8 kg DM cow-1day-1 (Bargo et al., 2003).
|
83 |
A case study of a Future Search Conference and the ripple effect on organization learning and developmentReynolds, Burton January 2008 (has links)
Thesis (Ed.D.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / This is a case study of the impact a future search conference had on Gas Distribution and Delivery, a business within the Public Service of New Jersey utility company as it made a major transition from a regulated monopoly to a competitive, deregulated business. The study found that problems addressed were both technical and socio-technical.
The data displayed four "organization ripples." The first ripple shows how large-scale change methodology can align diverse stakeholder groups, faced with complex challenges that require full collaboration to solve. This was a challenge for a traditional utility company that was very hierarchical and operated under a traditional command-and-control culture. The second ripple addressed the need for a new business model predicated on empowerment and the need for both efficiency and effectiveness of execution. Formal systems must be congruent with organization culture if new technology is expected to have a significant, positive impact. The third ripple focused on the importance of organization culture and its influence on collaboration in the wake of deregulation and changes in state regulation that remove historical barriers from competition and open up possibilities for competitive business--leading to an emphasis on customer response time. The fourth ripple highlighted how an organization can address its supervisors' perception of work, and how an empowered workforce can create a more integrative business strategy, where employees work together as one, not as many individual "tribes" within an organization. The concept of organization "fit" is explored as competitive advantage.
The study covered a ten-year span from 1997 to 2007. The initial work of the Future Search Conference covered a period of time from approximately 1997 to 2000, creating the foundation of all four ripples. In addition to documenting the conference, itself, the researcher also was able to interview the management team responsible for these initiatives in 2007 and to document the impact of the change effort over the entire ten-year period.
Implications are drawn about what role organization development may play in assisting 21st century companies with their learning and developmental needs. / 2031-01-02
|
84 |
Variabilita genu kappa-kasein u plemene brown swiss v České republiceSloupenský, Martin January 2017 (has links)
Kappa-casein has the general function in process of cheese production. Understanding the effect of gene polymorphism of kappa-casein to the nutritional and physical properties of milk may lead to more efficient breeding of dairy cattle. Within this thesis was genotyped by 240 brown swiss and jersey cows determinated using the PCR-RFLP. Then was performed association analysis of the impact of various genotypes on milk production parameters in the program SAS. An association between gene CSN3 polymorphism and milk yield was not statistically significant.
|
85 |
A Comparison of the Effects of Heat Stress on Milk and Component Yields and Somatic Cell Count in Holstein and Jersey CowsSmith, Daniel L 09 December 2011 (has links)
Objective 1 was to investigate effects of heat stress and breed on milk and component yield for Holstein and Jersey cows on the same farm. Objective 2 was to determine the effects of breed on udder health as measured by somatic cell count (SCC) during times of heat stress. Data were collected from DHIA records of 142 Jersey cows and 586 Holstein cows from the University herd at Mississippi State University. During heat stress Jersey milk yield and 4% fat corrected milk (FCM) increased (P<0.01). Holstein milk yield and FCM decreased during heat stress (P<0.01). Heat stress affected somatic cell count (SCC) although effects varied by intensity of heat stress. Breed did not have an affect on SCC. Milk fat and protein percentages declined for both breeds in heat stress conditions. Milk fat but not milk protein of Jersey cows increased as stress increased from mild to severe.
|
86 |
Lipid Quantification and Cryopreservation of In Vitro Produced Jersey Cattle EmbryosRhodes-Long, Katherine A. 01 August 2020 (has links) (PDF)
Cryopreservation of in vivo derived Jersey bovine embryos have resulted in a 10% lower pregnancy rate compared to other dairy breeds. Poor embryo survival after cryopreservation has been partially attributed to the high lipid content of Jersey embryos. In vitro-produced (IVP) bovine embryos have darker cytoplasm than their in vivo-derived counterparts because of higher lipid accumulation. High lipid accumulation is associated with impaired embryo quality. Forskolin is an adenylate cyclase activator that regulates cAMP levels in cells and has been shown to induce lipolysis in IVP embryos. L-carnitine is required for transport of fatty acids from the intermembrane space of the mitochondria into the mitochondrial matrix to support the process of β-oxidation, and enhances ATP production. We hypothesized that the lipid content of in vivo-produced and IVP Jersey embryos is higher than respective Holstein embryos and that forskolin + L-carnitine would reduce lipid content of IVP embryos and vitrification with embryo collapse would improve the cryosurvival of Jersey IVP embryos. The objectives of this experiment were (1) to analyze lipid content of in vivo and IVP Jersey and Holstein cattle embryos, (2) to evaluate the effect of forskolin + L-carnitine added to IVP culture media, and (3) evaluate Jersey IVP survival rates after three cryopreservation procedures. The factorial experimental design for objectives one and two used two breeds (Holstein and Jersey) and three embryo production methods (in vivo, IVP, and IVP + forsk/L-C). In vivo produced embryos (n = 27 blastocysts) were collected from superstimulated donors by routine procedures 7.5 days after AI. IVP embryos (n = 259 blastocysts) were produced by standard procedures; briefly, oocytes were aspirated from 2- to 8-mm follicles from slaughterhouse ovaries and matured for 24 h in SMM medium (BoviPro, MOFA Global, Verona, WI, USA). Matured oocytes were fertilized using semen from two different bulls for each breed, and embryos were cultured in BBH7 medium (BoviPro, MOFA Global) alone or with the addition of 1.5mM L-carnitine during maturation and embryo culture with forskolin (10 µM) added at Day 5 of culture at 38.5°C in 5% O2, 5% CO2, and 90% N2. The lipid content of embryos was quantified by staining Day 7 blastocysts with 1 μg mL–1 Nile red dye (580–596 nm), after which a digital photograph of the equatorial part of the embryo was taken at 40×, and fluorescence intensity (FI) was measured with Image Pro software. Data was analyzed by ANOVA, and means were compared using Tukey’s HSD. For the third objective, grade 1 Jersey IVP blastocysts (n=356) were divided into six treatments using a 2x3 factorial design comparing intact (IB) vs collapsed blastocoele (CB) and three cryopreservation methods: slow freezing (SF) vs vitrification using open pulled straws (OPS) or cryotop (CT). Slow freezing embryos were equilibrated in 0.7 M glycerol and 0.1 M galactose in holding media for 10 min, held for 10 min at -6°C, seeded after 5 min, decreased to -32 °C at 0.5 °C /min, held at -32°C for 5 min, and finally plunged into liquid nitrogen. Vitrified embryos were equilibrated in 1.5 M ethylene glycol (EG) for 5 min, exposed to 7 M EG + 0.6 M galactose for 30 s while loaded into OPS or placed onto CT, then immediately plunged into liquid nitrogen. SF embryos were thawed in air for 10 s and placed in a water bath at 37°C for 45 s. Vitrified embryos were warmed directly into holding medium at 37°C supplemented with 1.0 M, 0.5 M and 0.25 M galactose for 3 minutes each. Subsequently, embryos were cultured in BBH7 and re-expansion rates were assessed at 24 and 48h post warming and data was evaluated by GLIMX. For objective 1, Jersey and Holstein IVP embryos had higher lipid content than Holstein in vivo-produced embryos (P < 0.05), but were not different than Jersey in vivo-derived embryos (P > 0.1). Forskolin + L-carnitine lowered the lipid content (P < 0.05) of both IVP Jersey and Holstein embryos and was not different (P > 0.1) than in vivo-produced embryos. For experiment 2, re-expansion rates were higher for CT, than OPS, and SF (85 vs. 66 vs. 72% ± 0.4, respectively; p<0.05). Main effect means for re-expansion were higher for CB than IB (79 vs 68% ± 0.3; p<0.05). In conclusion, IVP embryos have higher lipid accumulation over Holstein in vivo embryos. Addition of forskolin and L-carnitine to embryo culture media has the potential to lower embryo lipid accumulation and possibly improve embryo viability and cryotolerance of IVP embryos. The CT method and collapsing the blastocoele prior to cryopreservation resulted in higher blastocyst survival rate. Further studies including transfer of embryos to recipients are necessary to corroborate these results.
|
87 |
Book Review of The Retreats of Reconstruction: Race, Leisure, and the Politics of Segregation at the New Jersey Shore, 1865–1920Nash, Steven 01 June 2018 (has links)
Review of: The Retreats of Reconstruction: Race, Leisure, and the Politics of Segregation at the New Jersey Shore, 1865–1920. David Goldberg. New York: Fordham University Press, 2016. ISBN 978-0-8232-7272-3. 188 pp., paper, $28.00.
Excerpt:
David Goldberg's The Retreats from Reconstruction: Race, Leisure, and the Politics of Segregation at the New Jersey Shore, 1865–1920 continues the historiographical trend that expands our understanding of Reconstruction and the Civil War's consequences beyond the plantation South. In this case, Goldberg examines the politics of race and segregation in the resort communities of Asbury Park and Atlantic City, New Jersey. He argues that over the last decade of the nineteenth century and first decades of the twentieth century, consumption and consumer freedom replaced the free labor political economy of the Civil War era at the Jersey shore. Subsequent clashes between working-class African Americans, middle-class white tourists, and white business elites prompted the implementation of Jim Crow segregation there by 1920 [...]
|
88 |
Splintered Loyalties: The Revolutionary War in Essex County, New JerseyWalsh, Gregory Francis January 2011 (has links)
Thesis advisor: Alan Rogers / Abstract: Splintered Loyalties: The Revolutionary War in Essex County, New Jersey By Gregory Francis Walsh Dissertation Director: Professor Alan Rogers "Splintered Loyalties" is a study of the people of Essex County, New Jersey and their experiences during the American Revolution. It is a careful analysis of their struggle to understand sweeping political change and their efforts to act in their community's best interest. This dissertation explores the momentous impact the Continental Congress's decision to declare independence had on Essex residents and stresses that both the British and American governments continued to fight for the hearts and minds of the people of Essex well after 1776. Relying on Essex County's military, economic, and judicial records and the public and private writings of ordinary people and their leaders, this project illustrates the waxing and waning of popular support for America's war effort between 1775 and 1783. Popular memory of the Revolution often divides the wartime population into distinct Patriot and Loyalist camps. This dissertation,however, argues that such a dichotomy recognizes neither the complexity of Patriots' and Loyalists' relationships with their wartime enemies nor the varying levels of commitment that Essex Patriots demonstrated in the war to establish a new republic. / Thesis (PhD) — Boston College, 2011. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: History.
|
89 |
Economic development functions of New Jersey community collegesMora, Peter L. January 1988 (has links)
Community colleges, especially in New Jersey, have been recognized as having an important role in the human resource development area of economic development. However, neither the literature nor state policy in New Jersey include a clear definition of the specific functions community colleges should have in economic development. Furthermore, current research does not include consensus on appropriate funding sources for functions in which community colleges could be involved. The purpose of this study was to determine the priorities among economic development functions of the community college as viewed by community college leaders, leaders of business and nonprofit organizations, and economic development specialists in New Jersey. These leader groups also identified how costs for these functions should be apportioned among three funding sources: the state/county; the organization; and the participant/student. Leader group views were obtained through a mail survey using a questionnaire developed for this study. The data were analyzed using descriptive statistics, analysis of variance (ANOVA), and Spearman Correlation Coefficient.
Major findings of the study include:
1. Leader groups displayed a moderate degree of consensus concerning importance ratings and rankings of functions. The data also revealed a high degree of agreement on the selection of a primary funding source for functions.
2. Community colleges providing job training and vocational and career counseling for unemployed persons were the most highly rated functions in the study.
3. Three functions concerning community college involvement in providing training for employees of local organizations were also rated highly: tailoring credit courses for supervisory personnel; providing certificate programs; and providing basic skills training.
4. Having the community college provide credit courses and workshops for small business leaders/entrepreneurs was also selected as an important function by all leader groups. / Ed. D.
|
90 |
Evaluation of corrective mating in Jersey cattleThomas, Christa Lynn January 1984 (has links)
First available appraisals for 67644 Jersey cows were used to estimate relative magnitudes of additive and selected sources of nonadditive genetic variation, and evaluate corrective mating programs for 13 linear type traits scored linearly from 50 to 99 points.
Estimates of additive genetic variances were 11 to 36 percent of within herd-classifier variance, with largest values for stature, strength, rump angle, rump width and udder depth. Dominance components ranged from 2 to 4 times as great as additive components for dairy character, rump width, and the udder traits; fore udder, rear udder height, rear udder width, and suspensory ligament, but were small for the other 7 traits. Maternal effects and the direct additive - additive maternal genetic covariance were unimportant.
Sire predicted differences and four measures of dam's merit (dam's phenotypic score, this score relative to herd average, dam's cow index, and half the maternal grandsire predicted difference) were used to predict offspring scores, deviated from herd average.
Sire regression coefficients were much larger than those for dam's measures, suggesting that sire evaluations should receive more weight than dam measures in a corrective mating context.
Mean squares for effects on offspring scores of interactions between categorical levels of sire predicted differences and dam measures generally were nonsignificant, indicating that additively combining measures is appropriate for predicting offspring performance.
Dam's cow index was found to be superior to dam's score for predicting mean performance of offspring groups (e.g., for large groups of offspring or over time) and is therefore preferred for corrective mating decisions. / Master of Science
|
Page generated in 0.0489 seconds