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1.
Trop Anim Health Prod ; 50(1): 121-128, 2018 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-28948472

RESUMEN

Data on breeding practices and traits of economic importance for the indigenous chicken (IC) were collected through personal interviews using structured questionnaires and direct observations of chicken management practices. The study was conducted from November 2015 to January 2016 in Rwamagana, Rulindo, Ruhango, Kicukiro and Muhanga districts of Rwanda. Data were collected and analysed through computation of indices, which represented a weighted average of all rankings of a specific trait. Spearman's non-parametric rank correlation was calculated for ranking of traits of economic importance to indicate the directional effects. The results on chicken ecotypes and their attributes showed that prolificacy, mature weight, disease tolerance, egg number and heat tolerance were highly preferred. The dwarf ecotype was most abundantly reared (38.84%) and considered to be significantly smaller and to have poorer growth rate, but to have better prolificacy than other indigenous chicken ecotypes. Selection of breeding cock and hen was based on disease tolerance, body weight at sexual maturity, body size and growth rate. In addition, for hen, mothering ability and egg fertility (Fer) were considered. Indices for the traits perceived by farmers as of primary economic importance were egg yield (0.093), disease tolerance (0.091), high growth rate (0.089), prolificacy (0.088), high body weight (0.087) and egg fertility (0.083). The most important traits considered by the marketers were body weight (BW), disease tolerance (Dtol), plumage colour (Pcol), egg yolk colour (EYC), meat quality (MQ), growth rate (GR) and egg yield (EY) whereas for consumers, meat quality, egg yolk colour, egg yield, body weight and growth rate were considered. Among traits perceived as important by farmers, a positive and significant correlation was found between BW and GR and Fer. Correlation was moderate for BW and prolificacy, drought tolerance (Drtol), Dtol and EYC. BW was negatively correlated with temperament (Temp), heat tolerance, Pcol and egg shell colour (ESC). Regarding marketers and consumers' preference rank correlation, positive and significant correlation was between BW and GR and MQ. As such, appropriate ecotypes (indigenous chicken) which have these characteristics need to be identified and utilised more based on their performance and adaption to the environment conditions to ensure efficient IC production.


Asunto(s)
Crianza de Animales Domésticos/economía , Crianza de Animales Domésticos/métodos , Cruzamiento/métodos , Pollos/genética , Comportamiento del Consumidor , Agricultores/psicología , Mercadotecnía/economía , Animales , Pollos/crecimiento & desarrollo , Femenino , Masculino , Fenotipo , Rwanda
2.
Poult Sci ; 96(12): 4245-4252, 2017 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-29053822

RESUMEN

Characterization of indigenous chicken (IC) production systems in Rwanda was conducted from November 2015 to January 2016 with the aim of understanding socio-economic characteristics, management of IC, production parameters, feed resources, and constraints faced by farmers rearing IC. A survey involving 206 households was carried out in 5 districts with the highest populations of IC using structured questionnaires. Data were analyzed using SAS software. The results showed that the majority of respondents (62.4%) were males and 37.6% were females. The majority of respondents (83.6%) had formal education. All family members were involved in the chicken husbandry practices. However, women (78%) were highly responsible for IC management activities. The family size averaged 5 persons (ranging 2 to 13) per household. Land was privately owned by farmers (84%) with a mean holding of 0.87 ha per household. The production system was mainly extensive with minimum provision of supplementary feeds. Chickens were being housed in separate houses at night and mating was uncontrolled. Breeding and replacement stocks were mainly sourced from the hatching of eggs using broody hens (60.68% of respondents). There were no vaccination programs, and ecto- and endo-parasites control was done when need arose. Egg production, income generation, meat production, and production of breeding stock were the main reasons of keeping IC. The first 3 main challenges facing IC production were diseases outbreaks, lack of investment capital, and predators. Others challenges, such as feed shortage, thieves, fluctuation of market price, lack of information on poultry rearing, and lack of chicken houses, also were mentioned. The IC production constraints mentioned need urgent mitigation measures to sustain utilization of IC against the changing climatic and economic conditions. Therefore, individual, public institution, and non-governmental organization efforts are required to develop sustainable breeding objectives directed to functions of IC and production challenges faced in the systems.


Asunto(s)
Crianza de Animales Domésticos/métodos , Pollos , Agricultores , Vivienda para Animales , Factores Socioeconómicos , Animales , Cruzamiento , Pollos/genética , Femenino , Humanos , Masculino , Rwanda
3.
J Dairy Sci ; 100(6): 4671-4682, 2017 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-28390719

RESUMEN

Dairy cattle industries contribute to food and nutrition security and are a source of income for numerous households in many developing countries. Selective breeding can enhance efficiency in these industries. Developing dairy industries are characterized by diverse production and marketing systems. In this paper, we use weighted goal aggregating procedure to derive consensus trait preferences for different producer categories and processors. We based the study on the dairy industry in Kenya. The analytic hierarchy process was used to derive individual preferences for milk yield (MY), calving interval (CIN), production lifetime (PLT), mature body weight (MBW), and fat yield (FY). Results show that classical classification of production systems into large-scale and smallholder systems does not capture all differences in trait preferences. These differences became apparent when classification was based on productivity at the individual animal level, with high and low intensity producers and processors as the most important groups. High intensity producers had highest preferences for PLT and MY, whereas low intensity producers had highest preference for CIN and PLT; processors preferred MY and FY the most. The highest disagreements between the groups were observed for FY, PLT, and MY. Individual and group preferences were aggregated into consensus preferences using weighted goal programming. Desired gains were obtained as a product of consensus preferences and percentage genetic gains (G%). These were 2.42, 0.22, 2.51, 0.15, and 0.87 for MY, CIN, PLT, MBW, and FY, respectively. Consensus preferences can be used to derive a single compromise breeding objective for situations where the same genetic resources are used in diverse production and marketing circumstances.


Asunto(s)
Intervalo entre Nacimientos , Peso Corporal/genética , Cruzamiento/métodos , Consenso , Industria Lechera/métodos , Leche/metabolismo , Animales , Bovinos , Kenia , Lactancia , Fenotipo , Carácter Cuantitativo Heredable
4.
J Dairy Sci ; 100(3): 2258-2268, 2017 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-28109609

RESUMEN

In developing countries minimal and erratic performance and pedigree recording impede implementation of large-sized breeding programs. Small-sized nucleus programs offer an alternative but rely on their economic performance for their viability. We investigated the economic performance of 2 alternative small-sized dairy nucleus programs [i.e., progeny testing (PT) and genomic selection (GS)] over a 20-yr investment period. The nucleus was made up of 453 male and 360 female animals distributed in 8 non-overlapping age classes. Each year 10 active sires and 100 elite dams were selected. Populations of commercial recorded cows (CRC) of sizes 12,592 and 25,184 were used to produce test daughters in PT or to create a reference population in GS, respectively. Economic performance was defined as gross margins, calculated as discounted revenues minus discounted costs following a single generation of selection. Revenues were calculated as cumulative discounted expressions (CDE, kg) × 0.32 (€/kg of milk) × 100,000 (size commercial population). Genetic superiorities, deterministically simulated using pseudo-BLUP index and CDE, were determined using gene flow. Costs were for one generation of selection. Results show that GS schemes had higher cumulated genetic gain in the commercial cow population and higher gross margins compared with PT schemes. Gross margins were between 3.2- and 5.2-fold higher for GS, depending on size of the CRC population. The increase in gross margin was mostly due to a decreased generation interval and lower running costs in GS schemes. In PT schemes many bulls are culled before selection. We therefore also compared 2 schemes in which semen was stored instead of keeping live bulls. As expected, semen storage resulted in an increase in gross margins in PT schemes, but gross margins remained lower than those of GS schemes. We conclude that implementation of small-sized GS breeding schemes can be economically viable for developing countries.


Asunto(s)
Cruzamiento , Industria Lechera , Países en Desarrollo , Animales , Bovinos , Análisis Costo-Beneficio , Femenino , Genómica , Masculino , Selección Genética
5.
J Genet Eng Biotechnol ; 15(2): 489-495, 2017 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-30647691

RESUMEN

In this study, indigenous chickens were collected from eight different regions in Kenya and kept at InCIP-Egerton University. These were studied using eighteen microsatellite markers to determine genetic variation. Statistics related to genetic variation were estimated using GenALEx6. Mean percentage polymorphic loci (PPL) was 96.71% and 4% genetic variance (p ≥ 0.003) was seen between the eight populations. MCW0123 marker had the highest genetic variance of 13% among populations (p ≥ 0.003) at 95% CI. Mean He ranged from 0.351 ± 0.031 (SIB) to 0.434 ± 0.022 (BM) with a grand mean He of 0.399 ± 0.011 across the populations using the microsatellite markers. Nei's genetic distance ranged from 0.016 (SIB and WP) to 0.126 (NR and SIB). DARwin6.501 analysis software was used to draw the population dendrogram and two major population clusters were observed, also seen with PCoA. This study found a lot of genetic variation and relatedness within and among populations. Based on the phylogenetic tree result, it is concluded that the clustering of the chicken populations in the present study is not based on geographical proximity. The microsatellite markers used in this study were suitable for the measurement of the genetic biodiversity and relationship of Kenyan chicken populations. These results can therefore serve as an initial step to plan the conservation of indigenous chickens in Kenya.

6.
J Anim Breed Genet ; 133(5): 404-13, 2016 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-26996153

RESUMEN

In general, livestock and fish farming systems in developing countries tend to be highly diverse in terms of agro-ecological conditions and market orientation. There are no studies that have investigated if and how this diversity translates to varying preferences for breeding objective traits. This is particularly important for breeding programmes that are organized on a national level (e.g. government-supported nucleus breeding programmes). The aim of this study was to investigate whether Nile tilapia farmers with diverse production systems and economic constraints have different preferences for breeding objective traits. The second objective was to derive a consensus breeding goal, using weighted goal programming that could be used for a national breeding programme for Nile tilapia. A survey was conducted among 100 smallholder Nile tilapia farmers in Kenya to obtain preference values for traits of economic importance, by using multiple pairwise comparisons. Individual and group preference values were estimated using analytical hierarchy process. Low-income farmers preferred harvest weight, while medium- and high-income farmers preferred growth rate and survival. Grouping farmers according to market objective (fingerling production or fattening) showed that fingerling producers preferred growth rate and survival, while fattening farmers preferred harvest weight, height and thickness. Weighted goal programming was used to obtain consensus preference values, and these were used to derive desired gains for a breeding goal of a national breeding programme that takes into account the diversity of smallholder production systems.


Asunto(s)
Acuicultura , Tilapia/genética , Animales , Acuicultura/economía , Cruzamiento , Femenino , Masculino , Tilapia/crecimiento & desarrollo , Tilapia/fisiología
7.
J Dairy Sci ; 97(12): 7963-74, 2014 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-25282422

RESUMEN

Dairy cattle breeding programs in developing countries are constrained by minimal and erratic pedigree and performance recording on cows on commercial farms. Small-sized nucleus breeding programs offer a viable alternative. Deterministic simulations using selection index theory were performed to determine the optimum design for small-sized nucleus schemes for dairy cattle. The nucleus was made up of 197 bulls and 243 cows distributed in 8 non-overlapping age classes. Each year 10 sires and 100 dams were selected to produce the next generation of male and female selection candidates. Conception rates and sex ratio were fixed at 0.90 and 0.50, respectively, translating to 45 male and 45 female candidates joining the nucleus per year. Commercial recorded dams provided information for genetic evaluation of selection candidates (bulls) in the nucleus. Five strategies were defined: nucleus records only [within-nucleus dam performance (DP)], progeny records in addition to nucleus records [progeny testing (PT)], genomic information only [genomic selection (GS)], dam performance records in addition to genomic information (GS+DP), and progeny records in addition to genomic information (GS+PT). Alternative PT, GS, GS+DP, and GS+PT schemes differed in the number of progeny per sire and size of reference population. The maximum number of progeny records per sire was 30, and the maximum size of the reference population was 5,000. Results show that GS schemes had higher responses and lower accuracies compared with other strategies, with the higher response being due to shorter generation intervals. Compared with similar sized progeny-testing schemes, genomic-selection schemes would have lower accuracies but these are offset by higher responses per year, which might provide additional incentive for farmers to participate in recording.


Asunto(s)
Cruzamiento , Bovinos/genética , Genómica , Animales , Bovinos/fisiología , Industria Lechera , Femenino , Genoma , Masculino , Linaje , Selección Genética
8.
Br Poult Sci ; 54(1): 62-75, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23444855

RESUMEN

1. The aim of the study was to evaluate the genetic and economic breeding objectives for an indigenous chicken (IC) breeding programme in Kenya. 2. A closed three-tier nucleus breeding programme with three breeding objectives and two selection schemes was simulated. The breeding objectives included IC dual-purpose (ICD) for both eggs and meat, IC layer (ICL) for eggs and IC broiler (ICB) for meat production. 3. Pure line selection scheme (PLS) for development of IC pure breeds and crossbreeding scheme (CBS) for the production of hybrids were considered. Two-and three-way crossbreeding strategies were evaluated under CBS and the impact of nucleus size on genetic gains and profitability of the breeding programme were investigated. 4. Males were the main contributors to genetic gains. The highest genetic gains for egg number (2·71 eggs) and growth traits (1·74 g average daily gain and 57·96 g live weight at 16 weeks) were realised under PLS in ICL and ICB, respectively. 5. The genetic response for age at first egg was desirable in all the breeding objectives, while that for fertility and hatchability were only favourable under ICL and PLS in ICD. Faecal egg count and immune antibody response had low, but positive gains except under PLS where the later was unfavourable. ICB was the most profitable breeding objective, followed by ICD and ICL under all the selection schemes. 6. Although PLS was superior in genetic gains and profitability and recommended in breeding programmes targeting ICL and ICB, a three line CBS should be considered in development of a dual-purpose breed. 7. Increasing the nucleus size beyond 5% of the IC population was not attractive as it resulted in declining profitability of the breeding programme.


Asunto(s)
Cruzamiento/métodos , Pollos/genética , Cruzamientos Genéticos , Crianza de Animales Domésticos/métodos , Animales , Pollos/crecimiento & desarrollo , Huevos , Femenino , Genotipo , Kenia , Masculino , Carne , Fenotipo
9.
Trop Anim Health Prod ; 43(8): 1575-82, 2011 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-21499962

RESUMEN

The aim of this study was to estimate genetic and phenotypic parameters for growth and survival traits of Sahiwal cattle in Kenya and determine their relationship to milk production and fertility. Performance records of 5,681 animals were obtained from the National Sahiwal Stud and the traits considered were: birth weight (kilogrammes), weaning weight (kilogrammes), pre-weaning average daily gain (grammes per day), post-weaning average daily gain (grammes per day), yearling weight (kilogrammes), mature weight at 36 months (kilogrammes), pre-weaning survival rate (SR), post-weaning survival rate (PSR), lactation milk yield (kilogrammes), age at first calving (days), and calving interval (days). The data was analysed using univariate and bivariate animal model based on restricted maximum likelihood methods, incorporating all known pedigree relationship among animals. The additive direct effects were more pronounced than maternal genetic effects in early and in post-yearling growth performance. The additive genetic variance and heritabilities were low for SR and PSR. The correlation between direct additive genetic and maternal genetic effect were negative for pre-yearling traits. Genetic and phenotypic correlations among growth traits and between growth and milk yield were positive, whilst those between growth and fertility were weak and negative. Correlations between survival and growth were generally low and positive. The estimates obtained in this study provide the necessary technical parameters for evaluating alternative breeding programmes and selection schemes for sustainable improvement of Sahiwal cattle.


Asunto(s)
Bovinos/fisiología , Fertilidad/fisiología , Leche/metabolismo , Animales , Bovinos/genética , Femenino , Fertilidad/genética , Genotipo , Kenia , Lactancia/fisiología , Masculino , Fenotipo
10.
Animal ; 5(11): 1780-90, 2011 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-22440419

RESUMEN

The objective of this study was to describe the lactation curve of dairy cattle in Kenya using a suitable lactation function in order to facilitate inclusion of partial lactations in national dairy cattle evaluation and to assess the effect of data characteristics on lactation curve parameters. Six functions were fitted to test day (TD) milk yield records from six parities of Ayrshire, Guernsey, Holstein Friesian, Jersey and Sahiwal cattle. Five datasets: DS-1 (12-TD dataset with randomly missing records), DS-2 (10-TD dataset without missing records), DS-3 (10-TD dataset with randomly missing records), DS-4 (7-TD dataset, with only TD 4 to 10 records) and DS-5 (7-TD dataset, with TD 1 to 4, 6, 8 and 10 records) depicting various recording circumstances were derived to assess the effects of data characteristics on lactation curves and to assess the feasibility of reducing the number of TD samples per lactation. The fit of the functions was evaluated using adjusted R(2) and their predictive abilities were compared using mean square prediction error, percentage of squared bias and the correlation between the predicted and actual milk yield. These criteria plus the changes in the parameters of curve functions and their associated standard errors were used in determining the effects of data characteristics on lactation curves. The mechanistic functions of Dijkstra (DIJ) and Pollott (APOL), and the incomplete gamma function of Wood (WD) had the highest adjusted R(2) > 0.75. The APOL function was eliminated due to convergence failures when analysis of individual lactations within breeds was carried out. Both DIJ and WD had good predictive ability, although DIJ performed slightly better. Convergence difficulties were noted in some DIJ analysis where data were limiting. Missing records, especially at the beginning of a lactation, greatly influenced parameters a and b of the functions. It also resulted in estimates with large standard errors. Missing records in later lactation hardly affected the parameter estimates. The WD and DIJ functions showed superior fit to the data. The WD function demonstrated higher adaptability to various data characteristics than DIJ and could be used in situations where animal recording is not consistently practised and where recording of animal performance is routinely practised. DIJ function had high data requirements, which restricts it to dairy systems with consistent recording, despite easy physiological interpretation of its parameters. The number of TD per lactation could be reduced by minimising sampling frequency in the later lactation while maintaining the monthly sampling frequency in early lactation.

12.
Trop Anim Health Prod ; 42(7): 1487-92, 2010 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-20419472

RESUMEN

Data on animal identification systems and selection criteria for sheep and goats were collected from the Rendille and Gabra communities in northern Kenya. These were then analysed through computation of indices, which represented a weighted average of all rankings of a particular trait or identification system. The three most important records kept were castration (index = 0.224), dates of birth (0.188) and entries into the flock (0.185). Identification was done through ear notching (0.409), branding (0.248), and coat colour of the animals (0.150). Characteristics with index >or=0.200 were considered more important and included big body size (Rendille, 0.260; Gabra, 0.251) and milk yield (Rendille, 0.206) for the buck's dam. Big body size (Rendille, 0.264; Gabra, 0.245) and offspring quality (Rendille, 0.252; Gabra, 0.265) were considered important attributes for the buck's sire. Important qualities for the ram's dam were big body size (Rendille, 0.246; Gabra, 0.216), offspring quality (Rendille, 0.200; Gabra, 0.235), fat deposition (0.233) among the Rendille and drought tolerance (0.246) among the Gabra. For the rams' sire, big body size (Rendille, 0.235; Gabra, 0.233), offspring quality (Rendille, 0.200; Gabra, 0.235) and fat deposition (Rendille, 0.203; Gabra, 0.220) were considered important. The results from this study imply that pedigree and performance recording have been practiced through own intricate knowledge and that pastoralists have deliberate selection criteria. This information is the cornerstone in the establishment of appropriate breeding programmes in the slowly changing pastoral systems.


Asunto(s)
Sistemas de Identificación Animal/métodos , Cruzamiento/métodos , Cabras , Ovinos , Crianza de Animales Domésticos/métodos , Crianza de Animales Domésticos/organización & administración , Animales , Tamaño Corporal/genética , Tamaño Corporal/fisiología , Femenino , Cabras/genética , Cabras/fisiología , Kenia , Lactancia/genética , Lactancia/fisiología , Masculino , Carne/normas , Carácter Cuantitativo Heredable , Ovinos/genética , Ovinos/fisiología
13.
J Anim Breed Genet ; 127(1): 34-41, 2010 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-20074185

RESUMEN

The objective of this study was to develop a method to optimize the selection and mating decisions based on genotypic information with overlapping generations by applying mate selection algorithm. In this study, differential evolution algorithm was used to optimize numbers of mating between genotypes and the optimal numbers of males and females selected from each genotype over planning horizon. This method assumed a single biallelic QTL (Q and q) and was applied to a simple situation in a herd of pigs as an example. Four dominance degrees of gene: recessive, additive, complete-dominance and over-dominance were considered. For all dominance degrees, the frequency of the favourable allele in males selected for replacement increased rapidly. In contrast, the frequency of favourable allele in females selected for replacement increased more gradually. The superiorities in cumulative discounted performance (CDP) when the initial allele frequency was 0.5 over a case when the frequency was 0.05 over the planning horizon were greatly affected by dominance degrees. The CDP superiorities ranged from 24% for an over-dominant QTL to 91% for a recessive QTL.


Asunto(s)
Modelos Genéticos , Alelos , Animales , Evolución Biológica , Femenino , Genotipo , Masculino , Selección Genética , Factores de Tiempo
14.
Trop Anim Health Prod ; 42(3): 327-40, 2010 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-19711191

RESUMEN

The objective of this study is to describe the present organisational structure of Boran cattle breeding and develop a model breeding programme using a deterministic approach under the current structure of the Boran Cattle Breeders Society. A breeding unit of 13,000 cows supplying bulls to a commercial population of 39,000 cows was assumed. Selection criteria used were growth and reproduction traits while breeding objective traits targeted were growth, carcass, reproduction, survival, milk yield and feed intake traits. Higher selection intensity was possible for breeding sires resulting in higher genetic gains compared to dams even though selection accuracies were generally low. Annual genetic gains were positive except for dressing percentage, cow survival rate, and age at first calving. However, a reduction of age at first calving by 9.5 days obtained a return of Ksh 49.76. The overall monetary genetic gain obtained was Ksh 84.89 with a profit per cow per year of Ksh 377.98. The basic breeding programme could be expanded to accommodate a larger population of Boran cattle. The implications of the results are also discussed.


Asunto(s)
Agricultura/economía , Cruzamiento/economía , Bovinos/genética , Crianza de Animales Domésticos/economía , Animales , Femenino , Kenia , Masculino , Selección Genética
15.
Trop Anim Health Prod ; 41(5): 767-74, 2009 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-18975120

RESUMEN

This study estimated genetic and phenotypic parameters and annual trends for growth and fertility traits of Charolais and Hereford cattle in Kenya. Traits considered were birth weight (BW, kg), pre-weaning average daily gain (ADG, kg/day) and weaning weight (WW, kg); calving interval (CI, days) and age at first calving (AFC, days). Direct heritability estimates for growth traits were 0.36 and 0.21; 0.25 and 0.10; 0.23 and 0.13 for BW, ADG and WW in Charolais and Hereford, respectively. Maternal heritability estimates were 0.11 and 0.01; 0.18 and 0.00; 0.17 and 0.17 for BW, ADG and WW in Charolais and Hereford, respectively. Direct-maternal genetic correlations ranged between -0.46 and 1.00; -0.51 and -1.00; -0.47 and -0.39 for BW, ADG and WW in Charolais and Hereford, respectively. Genetic correlations ranged from -0.99 to unity and -1.00 to unity for growth and fertility traits respectively. Prospects for improvement of growth and fertility traits exist.


Asunto(s)
Bovinos/fisiología , Fertilidad/fisiología , Modelos Genéticos , Carácter Cuantitativo Heredable , Animales , Peso al Nacer/genética , Peso Corporal/genética , Bovinos/genética , Bovinos/crecimiento & desarrollo , Femenino , Fertilidad/genética , Kenia , Masculino , Modelos Estadísticos
16.
Trop Anim Health Prod ; 41(5): 741-8, 2009 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-18958578

RESUMEN

Direct and maternal (co)variance components and genetic parameters were estimated for growth and reproductive traits in the Kenya Boran cattle fitting univariate animal models. Data consisted of records on 4502 animals from 81 sires and 1010 dams collected between 1989 and 2004. The average number of progeny per sire was 56. Direct heritability estimates for growth traits were 0.34, 0.12, 0.19, 0.08 and 0.14 for birth weight (BW), weaning weight (WW), 12-month weight (12W), 18-month weight (18W) and 24-month weight (24W), respectively. Maternal heritability increased from 0.14 at weaning to 0.34 at 12 months of age but reduced to 0.11 at 24 months of age. The maternal permanent environmental effect contributed 16%, 4% and 10% of the total phenotypic variance for WW, 12W and 18W, respectively. Direct-maternal genetic correlations were negative ranging from -0.14 to -0.58. The heritability estimates for reproductive traits were 0.04, 0.00, 0.15, 0.00 and 0.00 for age at first calving (AFC), calving interval in the first, second, and third parity, and pooled calving interval. Selection for growth traits should be practiced with caution since this may lead to a reduction in reproduction efficiency, and direct selection for reproductive traits may be hampered by their low heritability.


Asunto(s)
Bovinos/crecimiento & desarrollo , Bovinos/genética , Modelos Genéticos , Carácter Cuantitativo Heredable , Reproducción/genética , Animales , Peso al Nacer/genética , Peso Corporal/genética , Cruzamiento , Femenino , Kenia , Masculino , Modelos Estadísticos
17.
Trop Anim Health Prod ; 41(3): 307-20, 2009 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-18584299

RESUMEN

Production objectives and breeding practices of smallholder households participating in dairy goat breeding projects were analysed in relation to their ability to bring about sustainable genetic improvement in the dairy goat flocks in Kenya. A stratified survey involving 311 goat keepers in 4 project sites was used. This employed both qualitative and quantitative research methods to get a holistic view of dairy goats, and take into account the full array of contributions of dairy goats to the smallholder households. Milk production and sales of breeding stock were high priority functions for the objective to create a financial buffer. The breeding objective traits that farmers perceived as being of primary importance were milk yield, growth rate, body size, fertility and disease tolerance. There were logical trade-offs in the choice of these traits by farmers. Female dairy goats were mainly culled due to old age, poor fertility, small body size and poor health. Farmers did not place a large significance on unsatisfactory milk performance when culling female goats, mainly due to the very small production size and the high demand existing for breeding animals. Factors affecting milk yield and flock size presented satisfied a P<0.1 significance level. The performance levels of dairy goats were mainly influenced by breeding strategies and the resource availability at the farm level. The optimisation of genotype x environment interactions remains the biggest challenge given the objectives set by the farmer.


Asunto(s)
Cruzamiento/métodos , Cabras/genética , Cabras/fisiología , Lactancia/fisiología , Leche/metabolismo , Animales , Industria Lechera/métodos , Susceptibilidad a Enfermedades , Femenino , Predisposición Genética a la Enfermedad , Cabras/crecimiento & desarrollo , Kenia , Lactancia/genética , Leche/química
18.
J Anim Breed Genet ; 125(2): 84-8, 2008 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-18363973

RESUMEN

The effect of parental genotype and paternal heterosis on litter size (LS), total litter birth weight (TLW) and average litter birth weight (ALW) was analysed utilizing data from a crossbreeding programme involving the exotic German Fawn goats and local Katjang goats in Malaysia. In this study, these traits were regarded as traits of the litter to consider the effect of service sire genotype. The results revealed that LS was significantly influenced by the genotype of sire. The genotypes of sire and dam had significant effects on TLW and ALW. Estimates of crossbreeding parameter showed significant and negative influence of paternal heterosis on TLW and ALW while there was no significant effect of paternal heterosis on LS. The results of this study stress the need to reconsider the use of local males in the tropics.


Asunto(s)
Peso al Nacer/genética , Cabras/genética , Tamaño de la Camada/genética , Animales , Femenino , Genotipo , Vigor Híbrido , Hibridación Genética , Malasia , Masculino , Embarazo
19.
Animal ; 2(7): 1013-8, 2008 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22443701

RESUMEN

The objective of this study was to calculate cumulative discounted expressions (CDE) for Japanese Black sires carrying a single defective allele in a herd by applying the gene-flow method to investigate the expression pattern of homozygous recessive genotype and to evaluate the monetary loss of using these sires. A single biallelic locus was considered with A representing the dominant allele and a representing the recessive allele. The gene-flow method was modified to consider the fitness of homozygous recessive genotype. Input parameters representing a typical situation in a Japanese Black cattle herd were used to calculate the CDE and the loss of using carrier sires. The effects of initial allele frequency and fitness on the CDE were determined for Aa and AA sires. The CDE of Aa sires were larger than those of AA sires under all initial allele frequencies and fitness. The difference in the CDE between using Aa and AA sires was largest when fitness was 0 (lethal recessive condition). The differences in the loss between Aa and AA sires were larger with increasing initial allele frequencies in lethal recessive condition. Applying the method used in this study to defects reported in Japanese Black cattle and with a population size of 628 000, the difference in the loss between using Aa and AA sires was US$48 575 800 and US$74 418 000 in the case of Band-3 and Claudin-16 deficiencies, respectively. The approach used in this study could be applied to other genetic defects in different breeds and species.

20.
Trop Anim Health Prod ; 39(7): 467-75, 2007 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-17969710

RESUMEN

Economic values for production traits (milk yield, MY, kg; 12-month sale weight, LW, kg; consumable meat percentage, CMP) and functional traits (doe live weight, DoWT, kg; number of kids weaned, NKW; kidding frequency, KF; kidding rate, KR, %; doe weaning rate, DoWR, %; doe survival rate, DoSR, %; post-weaning survival rate, PoSR, %; pre-weaning survival rate, PrSR, % and; residual feed intake of yearlings, RFIgamma, kg and does RFId, kg) were estimated for the Kenya Dual Purpose goat (KDPG) for systems under two bases of evaluation. The production systems included smallholder low-potential (SLP), smallholder medium-potential (SMP) and smallholder high-potential (SHP), while the bases of evaluation considered were fixed flock-size and fixed feed resource. Under both bases of evaluation, economic values were highest in SMP apart from the economic values for feed intake-related traits (RFIy and RFId). In SMP, the economic values under fixed flock-size scenario were KSh 71.61 (LW), 20.90 (MY), 45.20 (CMP), 13.68 (NKW), 3.61 (KF), 6.52 (KR), 12.39 (DoWR), 22.96 (DoSR), 22.87 (PoSR), 13.18 (PrSR), -2.76 (RFIy) and -3.00 (RFId). The corresponding economic values under fixed feed resources scenario were KSh 73.28, 29.39, 45.20, 16.91, 4.76, 9.45, 13.84, 25.67, 25.15, 16.19, -2.76 and -3.00. Generally in all production systems, economic values for most traits were higher under fixed feed resource than under fixed flock-size scenario. In all systems, the economic values for most of the traits were sensitive to changes in prices of feed, milk and meat. The positive economic values for most traits under fixed flock-size scenario and fixed feed resource indicates that a unit increase in genetic merit for the traits would have a positive effect on the profitability of the systems.


Asunto(s)
Alimentación Animal , Cruzamiento , Industria Lechera/economía , Industria Lechera/métodos , Cabras/fisiología , Leche/metabolismo , Animales , Análisis Costo-Beneficio , Femenino , Cabras/genética , Cabras/crecimiento & desarrollo , Kenia , Lactancia , Tamaño de la Camada , Leche/economía , Tasa de Supervivencia , Destete , Aumento de Peso
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