Short Generation Interval Research Articles

Unlocking the potential of local rabbit population: morphological insights for sustainable rabbit farming in Burkina Faso’s challenging environments

This study explores the potential of rabbits as a sustainable solution for poverty alleviation and food security in Burkina Faso, a country facing socio-economic and environmental challenges. In the context of limited resources and employment opportunities, rabbits offer advantages such as small size, short generation interval and high reproductive capacity. The research focuses on characterising the morphology of Burkina Faso’s local rabbit population, comparing it with two Italian breeds: a local medium-growing breed called Leprino di Viterbo (LV) and a fast-growing hybrid (a crossbred New Zealand × California, NZC). Utilising path analysis and principal component analysis, the study identifies key morphometric traits crucial for breeding programs and examines the influence of specific traits on body weight (BW) gain and heat stress resilience through ‘Transpiration Indexes.’ Findings highlight the importance of variables like chest girth (CG), abdominal girth (AG), rump width (RW) and nose to shoulders length (NSL) in influencing body weight (BW) and reveal significant size and shape differences among the breeds. The study suggests potential climate adaptation in Burkina Faso’s rabbit population, providing practical insights for breeding programs in resource-constrained regions. This research not only advances scientific understanding but also provides practical insights for breeding programs in resource-constrained regions, emphasising the importance of certain morphological traits for heat dissipation.

Development of a non-programmable sperm cryopreservation technique in dwarf surfclams Mulinia lateralis–a potential model species for bivalve research

Sperm cryopreservation technique has been published in many farmed bivalve species. One of the key factors preventing its application in aquaculture and/or cryobanking is the knowledge gap on the performance of resultant progeny at late developmental stages and subsequent generations. An effective strategy to overcome these challenges is to use a model species with a short generation interval, such as the dwarf surfclam Mulinia lateralis (three months). This study evaluated the parameters key to the development of a non-programmable sperm cryopreservation technique in this species, with a D-stage larval rate similar to control being achieved when the sperm were cryopreserved under the conditions (cryoprotectant agent: 8% dimethyl sulfoxide; equilibration period: 10 min; rack height: 4 cm; thawing temperature: 60°C and sperm to egg ratio: 1100:1) optimized. This technique is the most common method applied in bivalve and the results from this study were all within the ranges published for other bivalve species, indicating this species would be an ideal bivalve model species for addressing cryopreservation evaluation issues that need a long extended time to collect data and/or challenging field experiments.

CRISPR/Cas Genome Editing—Can It Become a Game Changer in Future Fisheries Sector?

Fisheries and aquaculture are the fastest-growing food-producing sector and rapidly becoming an important element for the global food security since they are the primary source of seafood and high animal protein in the human diet. Genome editing offers new possibilities such as the clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein (Cas9) technology, which has the potential to accelerate the sustainable genetic improvement in fisheries and aquaculture. The CRISPR/Cas9 system has four key components, namely, target DNA, Cas9, the protospacer adjacent motif sequence, and the guide RNA or single-guide RNA. CRISPR/Cas is cheaper, easier, and more precise than the other genome editing technologies and can be used as a new breeding technology in fisheries and aquaculture to solve the far-reaching challenges. The attributes like high fecundity, external fertilization, short generation interval, the established method of breeding, and the larval rearing of most aquaculture species have advantages for CRISPR/Cas9 genome editing applications. CRISPR/Cas9 has recently been applied to the traits valued in some aquaculture species (almost >20 species), targeting the main traits of traditional genetic improvement initiatives like growth, disease resistance, reproduction, sterility, and pigmentation. Genome editing can fast forward the breeding process with precision where changes occur in the targeted genes. The probability of desired changes occurring and passing the trait in the next generation is high, so it takes 1-3 generations to establish a breed. Moreover, CRISPR/Cas genome editing rapidly introduces favorable changes by disrupting genes with targeted minor changes, in contrast to transgenesis, which introduces foreign genes into the host genome and thereby alleviates major public concerns on safety. Although the CRISPR/Cas technology has a tremendous potential, there are several technical challenges and regulatory and public issues concerning the applications in fisheries and the aquaculture breeding sector. Nonetheless, the exciting point in the CRISPR/Cas9 genome editing is that two CRISPR-edited fish, namely, red sea bream and tiger puffer developed by the Kyoto-based startup got approval and are now on the market for sale, and another fish, FLT-01 Nile tilapia developed by the AquaBounty, is not classified under genetically modified organism regulatory. However, there is still a way to go before it revolutionizes and becomes viable in commercial aquaculture as the new breeding technology for aquaculture-important traits and species.

Accuracy of Genomic Selection for Important Economic Traits of Cashmere and Meat Goats Assessed by Simulation Study.

Genomic selection in plants and animals has become a standard tool for breeding because of the advantages of high accuracy and short generation intervals. Implementation of this technology is hindered by the high cost of genotyping and other factors. The aim of this study was to determine an optional marker density panel and reference population size for using genomic selection of goats, with speculation on the number of QTLs that affect the important economic traits of goats. In addition, the effect of buck population size in the reference population on the accuracy of genomic estimated breeding value (GEBV) was discussed. Based on the previous genetic evaluation results of Inner Mongolia White Cashmere Goats, live body weight (LBW, h2 = 0.11) and fiber diameter (FD, h2 = 0.34) were chosen to perform genomic selection in this study. Reasonable genome parameters and generation transmission processes were set, and phenotypic and genotype data of the two traits were simulated. Then, different sizes of the reference population and validation population were selected from progeny. The GEBVs were obtained by six methods, including GBLUP (Genomic Best Linear Unbiased Prediction), ssGBLUP (Single Step Genomic Best Linear Unbiased Prediction), BayesA, BayesB, Bayesian ridge regression, and Bayesian LASSO. The correlation coefficient between the predicted and realized phenotypes from simulation was calculated and used as a measure of the accuracy of GEBV in each trait. The results showed that the medium marker density Panel (45 K) could be used for genomic selection in goats, which can ensure the accuracy of the GEBV. The reference population size of 1,500 can achieve greater genetic progress in genomic selection for fiber diameter and live body weight in goats by comparing with the population size below this level. The accuracy of the GEBV for live body weight and fiber diameter was better when the number of QTLs was 100 and 50, respectively. Additionally, the accuracy of GEBV was discovered to be good when the buck population size was up to 200. Meanwhile, the accuracy of the GEBV for medium heritability traits (FDs) was found to be higher than the accuracy of the GEBV for low heritability traits (LBWs). These findings will provide theoretical guidance for genomic selection in goats by using real data.

Gender Based Disparity in Poultry Production in Ethiopia

A review was carried out with the aim of providing the comprehensive and organized information on Gender based disparity in Poultry production day to day activities. Poultry production has an important economic, social and cultural role in rural areas of developing Countries like Ethiopia where women’s involvement and contribution has not been much recognized even though they contribute a lot for agricultural sector. According to this review results, Village chicken production has a fundamental role in capital build up, poverty minimization, malnutrition and hunger reduction among the resource poor households in developing countries of the world because of their short generation intervals, low input requirements for production, good scavengers and adaptation to harsh production environments. This review results also indicated that women are generally less able than men to participate in economic opportunities because they face a work burden that men do not. In most societies, women are responsible for most of the household and child-rearing activities as well rearing of small livestock, although norms differ by culture and over time. The review went further to address and compile available findings concerning the challenges poultry farmers face and showed that the most serious constraints hindering poultry production was predator followed by flock mortality and prevalence of diseases, and low production.

Spermatogonia From Cryopreserved Testes of Critically Endangered Chinese Sturgeon Efficiently Colonized and Preferentially Proliferated in the Recipient Gonads of Yangtze Sturgeon.

The critically endangered Chinese sturgeon, Acipenser sinensis, presents late sexual maturity and has a large body size. Germ cell transplantation is a powerful technique for the production of gametes from large-bodied species in closely related recipients with a smaller body size and shorter generation time. To accelerate reproduction of Chinese sturgeon, donor spermatogonia collected from the cryopreserved testes of 3-year-old Chinese sturgeon were intraperitoneally transplanted into 7-8 days post-hatch larvae of Yangtze sturgeon (Acipenser dabryanus) with shorter generation interval. At 2 months post-transplantation (mpt), donor spermatogonia had colonized in the 81.25% of recipient gonads, with average numbers about two times those of endogenous primordial germ cells. Within the next 2 months, the rate of endogenous germ cell division in females (2-3 times) was faster than that in males (once), whereas colonized donor-derived spermatogonia divided about 2-3 times and twice in recipient females and males, respectively. Furthermore, the expression of germ cell-related genes, dazl, dead end, and vasa, in transplanted fish was higher than that in non-transplanted fish, suggesting the incorporation and proliferation donor spermatogonia in recipient. At 18 mpt, donor-derived spermatogonia survived in the 75.00% of recipient gonads. These results showed that the somatic microenvironment of Yangtze sturgeon gonad can support the long-term colonization, proliferation, and survival of xenogeneic germ cells. Thus, this study suggested that small-bodied Yangtze sturgeon is promising recipient as surrogate for Chinese sturgeon gamete production.

Medical and Veterinary Ectoparasites' Importance: An Insight on Alternative Control

Numerous ectoparasites of people and domestic cattle remain a chronic concern in the contemporary world, despite many attempts at eradication. For many years, pesticide medications such as organophosphates, organochlorides, and synthetic pyrethroids were efficient in controlling these parasites; however, widespread use of these treatments has resulted in resistance in many target species. Domestic animals play a vital role in food production, producing meat, milk, and money. The agricultural communities raze livestock’s as an insurance and investment in contradiction of risk. Animals with short generation intervals and high fertility offer economic, managerial, and biological benefits, since milk production can start five or six months after mating and the first corpse can be sold in less than a year. Livestocks are also a main source of manure, which helps to fertilize the soil, as well as skin, which is one of the most significant products that generates foreign cash for the country. However, the combined effects of sickness, inadequate food, and bad management limit animal output. Parasitic sickness is one of the most common disorders in domestic animals and human, and it has a significant economic impact. Ectoparasites of livestocks are extensively dispersed with varying degrees of incidence, and are crucial in causing considerable economic damage to the agricultural community, the tanning and leather sector even throughout the wolrd, necessitating efficient control methods. Scabies mites, head lice, and bed bugs are important medical ectoparasites that pose a considerable public health threat, hence effective management strategies are required. Alternative management approaches have been developed in a number of ways, but more study is needed before they can be utilized to effectively regulate the ectoparasitic illnesses in the forthcoming. Keywords: Human; Livestocks; Parasites; Biological control; Chemical control

Rabbit Farming in India: An Overview

Domestic rabbit belongs to genus Oryctolagus cuniculus which has 38 important breeds and 77 varieties of European rabbits. The domestic rabbit is known to produce quality meat, fur and very fine quality animal fibre. Rabbit rearing has gained momentum in the recent years among the developing countries including India, owing to their small body size, rapid growth rate, high prolificacy, early maturity, shorter generation interval and ability to utilize forage and fibrous agricultural by-products. In India, there has been a rising awareness in recent years on the virtues of broiler rabbit production as an alternative means of alleviating food shortages. India is also one of the developing countries which are also facing meat shortage of 4.66 g/day against the recommended requirement of 87 g/day. In India, the total rabbit population has increased from 424 thousands in 2007 to 591.6 thousand in 2012 which is 39.55% increase in last 5 years.

Zebrafish, an In Vivo Platform to Screen Drugs and Proteins for Biomedical Use.

The nearly simultaneous convergence of human genetics and advanced molecular technologies has led to an improved understanding of human diseases. At the same time, the demand for drug screening and gene function identification has also increased, albeit time- and labor-intensive. However, bridging the gap between in vitro evidence from cell lines and in vivo evidence, the lower vertebrate zebrafish possesses many advantages over higher vertebrates, such as low maintenance, high fecundity, light-induced spawning, transparent embryos, short generation interval, rapid embryonic development, fully sequenced genome, and some phenotypes similar to human diseases. Such merits have popularized the zebrafish as a model system for biomedical and pharmaceutical studies, including drug screening. Here, we reviewed the various ways in which zebrafish serve as an in vivo platform to perform drug and protein screening in the fields of rare human diseases, social behavior and cancer studies. Since zebrafish mutations faithfully phenocopy many human disorders, many compounds identified from zebrafish screening systems have advanced to early clinical trials, such as those for Adenoid cystic carcinoma, Dravet syndrome and Diamond–Blackfan anemia. We also reviewed and described how zebrafish are used to carry out environmental pollutant detection and assessment of nanoparticle biosafety and QT prolongation.

Estimating Transmission Parameters for COVID-19 Clusters by Using Symptom Onset Data, Singapore, January-April 2020.

We estimated the generation interval distribution for coronavirus disease on the basis of serial intervals of observed infector–infectee pairs from established clusters in Singapore. The short mean generation interval and consequent high prevalence of presymptomatic transmission requires public health control measures to be responsive to these characteristics of the epidemic.

Epidemiological parameters of COVID-19 and its implication for infectivity among patients in China, 1 January to 11 February 2020.

BackgroundThe natural history of disease in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remained obscure during the early pandemic.AimOur objective was to estimate epidemiological parameters of coronavirus disease (COVID-19) and assess the relative infectivity of the incubation period.MethodsWe estimated the distributions of four epidemiological parameters of SARS-CoV-2 transmission using a large database of COVID-19 cases and potential transmission pairs of cases, and assessed their heterogeneity by demographics, epidemic phase and geographical region. We further calculated the time of peak infectivity and quantified the proportion of secondary infections during the incubation period.ResultsThe median incubation period was 7.2 (95% confidence interval (CI): 6.9‒7.5) days. The median serial and generation intervals were similar, 4.7 (95% CI: 4.2‒5.3) and 4.6 (95% CI: 4.2‒5.1) days, respectively. Paediatric cases < 18 years had a longer incubation period than adult age groups (p = 0.007). The median incubation period increased from 4.4 days before 25 January to 11.5 days after 31 January (p < 0.001), whereas the median serial (generation) interval contracted from 5.9 (4.8) days before 25 January to 3.4 (3.7) days after. The median time from symptom onset to discharge was also shortened from 18.3 before 22 January to 14.1 days after. Peak infectivity occurred 1 day before symptom onset on average, and the incubation period accounted for 70% of transmission.ConclusionThe high infectivity during the incubation period led to short generation and serial intervals, necessitating aggressive control measures such as early case finding and quarantine of close contacts.

Application of Genetically Engineered Pigs in Biomedical Research.

Progress in genetic engineering over the past few decades has made it possible to develop methods that have led to the production of transgenic animals. The development of transgenesis has created new directions in research and possibilities for its practical application. Generating transgenic animal species is not only aimed towards accelerating traditional breeding programs and improving animal health and the quality of animal products for consumption but can also be used in biomedicine. Animal studies are conducted to develop models used in gene function and regulation research and the genetic determinants of certain human diseases. Another direction of research, described in this review, focuses on the use of transgenic animals as a source of high-quality biopharmaceuticals, such as recombinant proteins. The further aspect discussed is the use of genetically modified animals as a source of cells, tissues, and organs for transplantation into human recipients, i.e., xenotransplantation. Numerous studies have shown that the pig (Sus scrofa domestica) is the most suitable species both as a research model for human diseases and as an optimal organ donor for xenotransplantation. Short pregnancy, short generation interval, and high litter size make the production of transgenic pigs less time-consuming in comparison with other livestock species This review describes genetically modified pigs used for biomedical research and the future challenges and perspectives for the use of the swine animal models.

The time scale of asymptomatic transmission affects estimates of epidemic potential in the COVID-19 outbreak

The role of asymptomatic carriers in transmission poses challenges for control of the COVID-19 pandemic. Study of asymptomatic transmission and implications for surveillance and disease burden are ongoing, but there has been little study of the implications of asymptomatic transmission on dynamics of disease. We use a mathematical framework to evaluate expected effects of asymptomatic transmission on the basic reproduction number R0 (i.e., the expected number of secondary cases generated by an average primary case in a fully susceptible population) and the fraction of new secondary cases attributable to asymptomatic individuals. If the generation-interval distribution of asymptomatic transmission differs from that of symptomatic transmission, then estimates of the basic reproduction number which do not explicitly account for asymptomatic cases may be systematically biased. Specifically, if asymptomatic cases have a shorter generation interval than symptomatic cases, R0 will be over-estimated, and if they have a longer generation interval, R0 will be under-estimated. Estimates of the realized proportion of asymptomatic transmission during the exponential phase also depend on asymptomatic generation intervals. Our analysis shows that understanding the temporal course of asymptomatic transmission can be important for assessing the importance of this route of transmission, and for disease dynamics. This provides an additional motivation for investigating both the importance and relative duration of asymptomatic transmission.

Influence of Lactation Order and Lactation Stage on Physico-Chemical Properties of Pantja Goat Milk

Goat is a versatile animal having short generation interval with lower investment cost and higher prolificacy. The present study was carried out at Goat farm, LPM, GBPUAT, Pantnagar. During the entire study the fresh milk samples of Pantja goats were taken according to lactation order and stage viz., 1st (Upto 30 days), 2nd (31 to 60 days) and 3rd (above 61 days) stage of lactation were analyzed for physico-chemical properties. The values of milk composition were significantly affected by lactation order and stage of lactation and their interaction. The color of Pantja goat milk was perfectly white in all the lactation order and lactation stages. The specific gravity and boiling point of milk increased significantly from 1st to 3rd lactation order and with advancement of lactation stage. The milk composition; fat, protein, total solids, solids not fat, total ash and chemical properties viz.titratable acidity of milk was increased significantly in advanced lactation order and stage of lactation except, pH, water and carbohydrate which showed a declining trend

181 Enhancing the efficiency of poultry production by optimising selection objectives and breeding strategies

Abstract Poultry, in general, have been the most successful farmed species in efficiently producing protein, be it egg laying chickens or meat producing chickens or turkeys. This has been the result of 60–80 years of continuous selection and improvement of traits that effect overall efficiency. The innate physiology of birds, high reproductive rates and relatively short generation intervals have helped speed these improvements. The contribution of feed to production costs has increased efforts to accurately measure feed intake, and selecting for efficient feed utilisation have been significant. Selection for feed efficiency forms an integral part of the breeding objective of the respective breeding programs, but in recent years other components of efficiency have become increasingly important within breeding objectives. Market segmentation, with greater volumes of fully deboned meat for further value added processing, has resulted in the optimisation of yield to feed for both broilers and turkeys. Allometric growth patterns, particularly late stage deposition of breast meat, gives rise to opportunities for optimisation of both slaughter age and weight. Genetic evaluations incorporating genomic information from birds with yield measurements is now implemented across both broilers and turkeys in many breeding programs. The implementation of genomic selection has benefits for not only yield, but also growth and feed efficiency, and we have shown improvements in genetic prediction of 11%, 23% and 31% for growth, breast meat and residual feed intake in turkeys, respectively. Reproductive efficiency has also been improved in broilers, turkeys and particularly layers, by improving evaluations using genomic information. Altering egg production curves to maintain production persistency for increasingly longer time periods has also been important. Layer flocks are now routinely in production for up to 500 days and similar objectives are used for selection in both broiler and turkey reproduction.

Ruminant phylogenetics: A reproductive biological perspective

Summary. Phylogenetics is the study of evolutionary relationships among species. Phylogenies are based on the comparison of large numbers of characteristics among species. Traditionally, the field of phylogenetics was dominated by paleontologists so the characteristics studied were structural, often skeletal. The field of phylogenetics was revolutionized in the 1980s as scientists began using molecular data, first amino acid, then nucleotide sequences. This led to the inclusion of more characteristics and many more extant species in these analyses. We now have very well characterized phylogenies for most major groups of mammals, including the ruminants (Ruminantia, a suborder within Artiodactyla). The ruminants are traditionally divided into six families: Tragulidae (mouse deer), Moschidae (musk deer), Cervidae (true deer), Antilocapridae (pronghorn), Giraffidae (giraffes and okapis) and Bovidae (horned ruminants). Despite extensive research, some phylogenetic relationships within the Ruminantia have not been completely resolved. For example, the precise relationships among the six ruminant families is not clear. The relationship of cattle (Bos taurus) to other large bovids (gaurs, bison, yaks, etc.) remains to be determined. Ultimately, more extensive characterization and comparison of ruminant genomes will define these relationships. In the mean time, we may be able to use reproductive characteristics to help clarify some of the unresolved phylogenetic relationships. Reproductive characteristics can vary greatly among species. Much of this variation is recently evolved, making it particularly useful in defining relationships among closely related species or groups. Placentally expressed gene families, reproductive behaviors and even interspecies embryo transfer studies may provide novel ways to resolve the few remaining phylogenetic questions in ruminants. Recognizing that the vast majority of existing phylogenies are extremely accurate, reproductive biologists can use them to make more rapid progress in extending research from one species to another. Phylogenies also can provide a background to determine how specific reproductive characteristics evolved over time. Finally, phylogenetics and reproductive biology can be brought together to study the fundamental biological process of speciation. Speciation is the study of how new species arise. Establishing reproductive isolating barriers (variation) between a nascent species and its immediate ancestor is a fundamental part of the speciation process. Much of the work in this area has been done using invertebrate species with very short generation intervals. Mammalian models to study speciation are severely lacking. Ruminants may be an ideal group in which to study this process since they have the two prerequisites essential to this type of work, 1) a large number of recently-evolved extant species and 2) well characterized and dated phylogenies. The body of fundamental research characterizing reproductive systems in a few ruminants is enormous. We are at a point where we can start to extend more of this research to other ruminant species to address the process of speciation, and perhaps other, fundamental biological questions.

Upgrading breeding value estimation in beef cattle

This paper gives a summary of the possibility for applying genomic information for breeding value estimation in beef cattle breeding. This process is called genomic prediction and is now widely used in dairy cattle globally as well as in some beef and sheep populations. The advantage of genomic prediction is a more accurate estimate of the genetic merit of an individual at a young age thereby facilitating greater annual genetic gain, predominantly through shorter generation intervals. Genomic predictions are more advantageous for sex-linked (e.g., milk yield), low heritability (e.g., fertility) and difficult-to-measure (e.g., feed intake) traits. The larger the reference population, on average, the more accurate the genomic predictions; additionally, the closer genetically the reference population is to the candidate population, the greater the accuracy of genomic predictions. Research is continuing on strategies to generate accurate genomic predictions using a reference population consisting of multiple breeds (and crossbred). Retrospective analysis of real-life data where genomic predictions have been operation for several years clearly shows a benefit of this technology.

Genetic associations between mature size and condition score of Nelore cows, and weight, subjective scores and carcass traits as yearlings

The size and body condition of female livestock is critical for improving production efficiency. However, we know little about how height and body condition score in mature beef cattle are genetically related to traits observed when the animals are younger. In the present study, we used data from 321650 Nelore cattle, first, to compare genetic parameters and breeding values on the basis of different models employing weight (MW), height (MH) and body condition score (BCS) of mature cows (3–17 years old). Next, we estimated the genetic correlations between the three traits and assorted yearling traits (YW, weight; YC; conformation score; YP, precocity score; YM, muscling score; YN, navel score; LMA, longissimus muscle area; BF, back fat thickness). Finally, we obtained the expected direct responses to selection for MW, MH and BCS of cows and correlated responses for these traits when the selection was applied to yearling traits. For MW and MH, single-trait Bayesian analyses were used to evaluate the effects of including BCS when defining contemporary groups (BCS included, CG1; BCS not included, CG2). For BCS trait, linear and threshold animal models were compared. After, bi-trait analyses that included MW, MH or BCS with yearling traits were performed. The CG1 scenario resulted in a higher heritability for MW (0.45 ± 0.02) than did CG2 (0.39 ± 0.02). Both scenarios yielded the same heritability estimates for MH (0.35 ± 0.02). Sires’ rank correlations between predicted breeding values under CG1 and CG2 were 0.60–0.92 for MW and 0.90–0.98 for MH, considering different selection intensities. Thus, only for MW genetic evaluations, the incorporation of BCS in the definition of the contemporary groups is indicated. For BCS trait, the same sires were selected regardless of the model (linear or threshold). Genetic correlations between MW and five yearling traits (YW, YC, YP, YM and YN) ranged from 0.18 ± 0.03 to 0.84 ± 0.01. The MH had a higher and positive genetic association with YW (0.64 ± 0.02) and YC (0.54 ± 0.03), than with YN (0.18 ± 0.03). However, MH was negatively and lowly genetically correlated with YP (–0.08 ± 0.03) and YM (–0.14 ± 0.03). The BCS had positive genetic associations with all yearling traits, particularly with YP (0.61 ± 0.06) and YM (0.60 ± 0.07). Mature size and carcass traits exhibited a low to moderate negative genetic correlations. However, BCS had positive genetic associations with LMA (0.38 ± 0.12) and BF (0.32 ± 0.14). Despite a shorter generation interval, selection at the yearling stage will result in a slower genetic progress per generation than does direct selection for cow MW, MH or BCS. Moreover, using YW and YC as selection criteria will increase cattle size at maturity without altering BCS. Last, LMA or BF-based selection will reduce mature size, while improving BCS, as a correlated response.

Assessment of Reproductive Performance and Flock Composition of Small-houlders Sheep and Goat Production Systems Under Assiut Governorate

This study was aimed to recognize the reproductive performance and herd composition of sheep and goat in six studied area located in east and west river Nile at Assiut governorate. A set of semi-structured questionnaire was used to collect information from 300 sheep owners based on single-visit-interviews. The study revealed that farmers keep mixed livestock species. Sheep and goat production are the major livestock activity in located study area. The average farm size of households surveyed in Assiut Governoratewas 8.2 feddan. The farmers cultivated 50.74% and 50.86 % of their lands for green fodder and field crops in winter and summer, respectively. About 50.89 % of the total farm size area cultivated with animal fodder around the year. In summer 25.37%. Of the area was cultivated with field crops. The reproductive and productive performance of sheep and goats were discussed and data showed that, no significant differences were observed in lambing interval and age at first lambing between sheep and goats, while goats were significantly higher in litter size (P<0.01), lambing mortality (p<0.05) weaning weight (p<0.01) and age at marketing (p<0.05) than sheep. Generally, Sheep and goat production in the studied areas was constrained by different problems; where the major ones are availability and cost of feeds, limitation of land for the expansion of production and poor extension services. Sheep and goats are very important smallholder producers due to their biological factors such as short generation interval, twinning, short growth periods, do not require much space and low food requirements. In this domain, reasons of high lamb mortality rates should be identified and reduced in order to make sheep and goat production profitable and sustainable.

Assessment of Sheep and Goat (Small Ruminants) Production System in Esera District, of Dawro Zone, Southern Ethiopia

This study was conducted in Esera district Dawuro zone Southern Ethiopia with the objectives of assessing small ruminant production system. For the study one hundred thirty eight (HHs) owning small ruminant were selected randomly and semi-structured questionnaire was used to collect data on small ruminants’ production system, management, reproductive performances and availability of feed resources .The available feed resources are (a grass species, crop aftermath and 4 legumes species are the common ones). The average family size was 5.23 ± 0.195 per HH. Crop-livestock farming was the commonly used farming system (100%) with (69.1%) extensive and (30.9%) semi-intensive production system. The mean total land holding was 3.1288 ± 0.19 ha per HH and was significant (P<0.05) varied across agro-ecologies. The average sheep and goat flock size per HH was 6.08 ± 0.183 and 5.69 ± 0.236 respectively and was significantly (p<0.05) varied across agro-ecologies. The purpose of keeping small ruminants in District was for cash income, as an insurance, meat, manure and as means of wealth accumulation with index of 0.32, 0.29, 0.16, 0.13 and 0.08 respectively. Natural mating is the most widely used in their breeding practice almost (100%) in HL (High land), ML (Mid land), and LL (Low land). Grazing and browsing on natural pasture and leguminous tree species are commonly used in their feeding system. Majority (80.7%) of HHs are keeping small ruminants in their living house. The source of water used for their animals and themselves as well is from river, tap, rain and harvested water depending on the season. Internal and external parasites are the first and second ranking diseases and parasites which affects the small ruminants in the study area. For sheep, estimated average puberty age is (6.6 ± 0.12 months for male and 7.7 ± 0.16 months for female), age for first lambing (12.7 ± 0.16 month) and lambing interval (8.4 ± 0.17 month) were significantly Higher (P<0.05) in the HL than in ML and LL. For Goats, estimated average puberty age is (7.04 ± 0.10 months for male and 7.40 ± 0.10 months for female), first Kidding age is (13.04 ± 0.16 months) and lambing interval (8.5 ± 0.12 months) were significantly Higher (P<0.05) in the HL than in ML and LL agro ecology. The major opportunity of small ruminant production is that they requires short generation interval, high market demand smaller space and capital investment with index of 0.26, 0.24 and 0.23 respectively and the major constraints of small ruminant productions were Disease and parasite, feed shortage, insufficient grazing land were the major complaints told by our respondents.