Controlled Breeding Programs Research Articles

Reproductive cycle of the temperate sea cucumber Holothuria tubulosa in the northeastern Aegean Sea

AbstractObjectiveThe aim of this study was to determine the reproductive cycle and spawning frequency of the sea cucumber Holothuria tubulosa in the northeastern Aegean Sea.MethodsThe study covered a period of 12 months, beginning in October 2018 and concluding in September 2019. During this period, sea cucumber samples were collected monthly. Macroscopic and histological examinations of gonadal tubules were conducted to provide credible information for fishery management and aquaculture.ResultThe sex ratio of the sampled population was 1:1.3, with 95 males and 130 females. The drained body weights at 50% maturity were 70.90 g for females and 70.80 g for males. The total length at 50% maturity was estimated at 18.58 cm for females and 18.05 cm for males. Gonad maturation was initiated in March and progressed to spawning stages between July and August. From September to February, the gonads were in postspawning and recovery stages. A strong linear correlation was determined between the gonad index and the seawater temperature in the area.ConclusionThe information provided is expected to improve stock management, enforce fishery regulations, and support controlled breeding programs. These measures aim to preserve the natural populations of Holothuria tubulosa and guarantee the long‐term viability of the species in the wild.

Controlled breeding in dairy cows. Part 2: selection and ethical implications

Background: Controlled breeding programmes describe timed artificial insemination (TAI) protocol choice and a strategy for their implementation, encompassing when they will be used and which cattle will be enrolled. A holistic approach to the reproductive management of every dairy herd, tailored to meet the requirements and expectations of the individual client, is essential if success of a controlled breeding programme is to be maximised.Aim of the article: This article, the second of a two‐part series, describes strategies for implementation of controlled breeding programmes on dairy farms. It considers factors aside from the TAI protocol that are essential for the success of any programme, as well as the ethical implications of hormone use in dairy cattle. The first part, published in last month's issue of In Practice, discussed common TAI protocols, how they manipulate ovarian activity and how to optimise protocol selection.

Controlled breeding in dairy cows. Part 1: bovine oestrus cycle and synchronisation

Background: Timed artificial insemination (TAI) as part of a controlled breeding programme is a reproductive strategy that eliminates the requirement for oestrus detection, guarantees the submission of enrolled cows and attempts to optimise the timing of insemination relative to ovulation. However, the success of TAI requires careful cow selection, diligent herd management and the selection of an appropriate synchronisation protocol.Aim of the article: This article, the first in a two‐part series, outlines the key ovarian follicular wave dynamics in the bovine oestrous cycle and the key goals of any synchronisation protocol. It describes the most commonly used drugs, their actions and how they can be combined into effective synchronisation protocols. The second part of the series, to be published in a subsequent issue of In Practice, discusses how to implement controlled breeding strategies on farms and considers factors aside from the TAI protocol that are essential for the success of any programme.

Tools to Improve Reproductive Performance of Dairy Cattle


 
 
 
 
 
 
 
 
 
 This paper discusses the use of parameters of herd reproduction in the diagnosis of infertility problems, the efficiency of oestrus detection, and the use of prostaglandins in controlled breeding programmes.
 
 
 
 
 
 
 
 
 

Evalution of Productive, Reproductive, Longevity and Lifetime Traits of Camel in Egypt

Data used in the present study were collected from history sheets of milk records (420) of 112 Maghrebi she-camels, number of dams were 55 sired by 15 sire, located at Center of Studies and Development of Camel production. Marsa Matrouh governorate belonging to Animal Production Research Institute (APRI), Ministry of Agriculture and Land Reclamation, Egypt. Data were covered the period from 2003 to 2017 year. Data were analyzed using the General Linear Model (PROC GLM) Procedure of the statistical analysis system (SAS, 2009). The model includes, season, year of calving as fixed effects, age at calving, days open and first milk yield as random effects. Age at first calving (AFC), days open (DO), calving interval (CI1), number of services per conception (NS/C1), total milk yield (TMY1) lactation period (LP1), number of lactation completed (NOL), culling age (CULL), productive life (PL), total lactation length (TLL), lifetime production (LMY), milk yield per lactation length (MPLL) and milk yield per day of productive life (MPPL) averaged 62.72 month, 168.30 days, 587.37 days, 2.17 services, 1408.76 kg, 410.15 days, 3.98 parity, 3861.80 days, 1940.63 days, 1389.74 days, 5266.02 kg, 4.08 kg and 3.03 kg, respectively. Age at first calving, total milk yield, days open, number of services per conception, number of lactation completed, culling age, length of productive life, lifetime production and milk yield per day of productive life were not affected by season of calving. Meanwhile, calving interval, total lactation length and milk yield per lactation length. Except for lactation period was highly significant (p<0.01). In addition, she-camels calving in Autumn and Winter had higher AFC, Spring and Summer are higher DO1, Autumn and Summer had longest CI1. Summer and Autumn had higher NS/C1 and Spring and Winter calving had higher TMY1 and LP1. Meanwhile, she-camels calving in Spring and Summer are higher NOL, CULL and PL. While, Autumn and Spring calving had longest TLL, Summer and Spring calving had higher LMY, Autumn and Winter calving had higher MPLL and Autumn and Summer calving had higher MPPL. Year of calving had significant effect (p<0.05) on AFC, CI1 and CULL. While, non-significant effect on DO1, NS/C1, TMY1, LP1, NOL, PL, LMY and MPPL. While, highly significant (p<0.01) effect on TLL and MPLL. Age at calving had non-significant effect on DO1, NS/C1, TMY1, NOL, CULL, PL, TLL, LMY and MPLL. While, significant effect (p<0.05) on LP1and MPPL. While, only highly significant effect (p<0.0001) on CI1. Days open had non-significant effect on AFC, NS/C1, TMY1, NOL, CULL, PL, TLL, LMY, MPLL. Also, milk yield increased linearly with the increase of DO. While, LP1 and CI1 affected highly significantly by days open and only significant effect (p<0.05) on MPPL. First milk yield had highly significant effect (p<0.01) on TMY1, NOL, CULL, PL, TLL and MPPL. Also, first milk yield increased linearly with advanced in age. While, had non-significant effect on both of LP1,AFC, DO1, CI1 and NS/C1. While, had significant effect (p<0.05) on LMY and MPLL. It was concluded that an improvement in camel productive and reproductive traits is possible both through improving management systems and utilization of controlled breeding programs.

Fertility in high-producing dairy cows: reasons for decline and corrective strategies for sustainable improvement

The fertility of dairy cows has declined worldwide and this change is surprising given the importance of good fertility to the dairy industry. The decline in fertility can be explained by management changes within the dairy industry and also negative genetic correlations between milk production and reproduction. Four primary mechanisms that depress fertility in lactating cows are anovulatory and behavioral anestrus (failure to cycle and display estrus), suboptimal and irregular estrous cyclicity (this category includes ovarian disease and subnormal luteal function after breeding), abnormal preimplantation embryo development (may be secondary to poor oocyte quality), and uterine/placental incompetence. The solution for improving fertility in high-producing dairy cows will include both short-term and long-terms components. For the immediate short-term, using high fertility sires and implementing controlled breeding programs will help. Controlled breeding programs improve reproductive efficiency in confinement-style dairy herds and can be combined with post-insemination treatments to enhance fertility. An additional immediate short-term solution involves changing the diet so that dietary ingredients invoke hormonal responses that benefit the reproduction of the cow. The short-term solutions described above do not address the fundamental need for correcting the underlying genetics for reproduction in high-producing dairy cows. Crossbreeding will improve reproductive performance perhaps because it alleviates inbreeding and also lowers production in cows with an extreme high milk production phenotype. The current crisis in dairy reproduction will be permanently solved, however, when the genetics for dairy reproduction are improved through a balanced genetic selection strategy.

The main challenges facing camel reproduction research in the 21st century

The reproductive efficiency of camels under their natural pastoral conditions is low. The reasons for this low reproductive efficiency include the short breeding season, the late age of reaching puberty and the long gestation period of 13 months. The introduction of controlled breeding programmes is important but several problems have to be considered. For example, oestrous behaviour is very vague and difficult to interpret, as it does not often relate to follicular development in the ovaries. In addition, all camelids are induced ovulators that normally ovulate only in response to mating, so alternative methods of inducing ovulation, such as injecting gonadotrophic hormones, have been investigated. The use of embryo transfer is becoming increasingly important but involves the necessity to superovulate the donors and synchronize the recipients so that they ovulate preferably 24 h after the donor. Superovulation can be achieved using exogenous gonadotrophins, although there is a high incidence of follicle luteinization before mating, of overstimulated ovaries and non-responsive females. The development of AI in camels is complicated by the difficulty of collecting semen and the gelatinous nature of the semen produced. However, diluting semen in Green Buffer and inseminating a minimum of 300 x 10(6) live spermatozoa has given encouraging results. The ability to control the follicular cycle of camels is leading to an improvement in reproductive efficiency.

Automatic systems for heat detection in cows as a tool for improving herd management

There are at least several ways of detecting bovine heat, which vary in accuracy, as well as in the effort and cost associated with the implementation and operation of equipment designed for this purpose. Heat in cows can be most easily detected by thorough and systematic observation of animals in the herd. Other methods include the measurements of vaginal mucosal resistance, the fitting of balloons with paint at the base of the tail or on the back, temperature measurements in the vagina, rumen and milk, and determination of progesterone levels in milk and blood. Currently, controlled breeding programmes, including timed artificial insemination (TAI) and automated estrus detection (AED) or activity monitoring system (AMS), are routinely introduced in high-performance dairy herds. Most of the commercially available heat detection devices are based on accelerometers or pedometers. These devices are capable of detecting heat in 81.4% to 91.3% of cows. The sensitivity of heat detection was 58.9% for accelerometers (Heatime), 63.3% for pedometers (SAE Afikim, Kibbutz Afikim, Israel), 56.7% for KaMaR markers and 35.9% for heat detectors (Scratchcard). When two of the three systems were combined (different combinations), the sensitivity increased to 75.9%. Similarly, after adding visual detection, sensitivity increased to 96% and specificity to 90% (for visual observation combined with AMS). Activity monitoring systems are a proven tool for improving the management of cows. They are an alternative to reproductive management based solely on traditional methods of detecting ovulation or hormone programmes (TAI) and they respect the well-being of animals. It seems, however, that further improvement in cows’ fertility on industrial cattle farms will be achieved by combining several different methods of heat detection and synchronization, rather than by using a single modern heat detection system..

The Hawaiian Horse by Dr. Billy Bergin and Dr. Brady Bergin

Reviewed by: The Hawaiian Horse by Dr. Billy Bergin and Dr. Brady Bergin Matthew Kainoa Wong The Hawaiian Horse. By Dr. Billy Bergin and Dr. Brady Bergin. Honolulu: University of Hawai‘i Press, 2017. xviii + 364 pp. Appendices. Glossary. Bibliographic references. Illustrated. Index. $42.00 cloth Dr. Billy Bergin and Dr. Brady Bergin’s The Hawaiian Horse narrates the history and legacy of the equine species. Their work is an important contribution to the equine field. The authors take the reader on a ride through history, recounting the origin of the equine species and the influence of the vaquero. They include an in-depth look at the worldwide transportation of livestock, equine roles in agronomy in industries of ranching, coffee, pineapple, rice, sugar and taro production in Hawai‘i, and examine mounts for recreational pleasure as well as highly competitive mounts. The authors depict people who have played important roles in the development of the horse in Hawai‘i, and they also go into detail about the usage of horses in sports. As veterinarians, Dr. Billy Bergin and Dr. Brady Bergin’s work would not be complete without including general and specific equine health issues in Hawai‘i. Each chapter [End Page 165] can be seen as a series of trails through time, creating a timeline that begins by contextualizing the origination of the equine species and ends with the future of Hawai‘i’s horse community. The insight that the authors provide on the influence of the vaquero is very comprehensive, illustrating the arrival of the vaquero in Hawai‘i in 1833 at King Kamehameha III’s royal request. The king was probably unaware that he not only launched “a major industrial/agricultural industry but also founded the Hawaiian paniolo culture that would parallel the image and skill of the vaqueros of New Spain and America’s West” (p. 30). The authors go into further detail, pointing out how the Hawaiian paniolo [cowboy] quickly retained what was taught by the vaquero and naturally excelled in horsemanship and cattle ranching. The authors also explain how the Hawaiian paniolo ho‘ohawai‘i (Hawaiianized) what they learned by interweaving their innate instincts as Native Hawaiian seafarers. The Hawaiian paniolo fashioned their saddles after the outrigger canoe, adapting all of the major saddle parts’ names from those of the outrigger canoe. They also note that as seafarers, Hawaiian’s were very adept at braiding cords of aho (sennet), so braiding rawhide to fashion their kaula ‘ili (rawhide rope) and other equipment came naturally. “Little did the vaquero know that the product of this mentoring would be world championship ropers only seventy-five years later” (p. 32). In the following chapters of the book, the authors illuminate the roles of the horse, donkey and mules in Hawaiian society. The Hawaiian paniolo pursued mounts with more endurance, hardiness, and easy-keeping qualities. These traits were found in the feral Hawaiian horses that were brought to Hawai‘i in 1803. These mounts had “hardened hooves of black granite that were a characteristic and a prepotent trait of feral horses that quickly became known as the Mauna Kea breed” (p. 65). The desire for the preservation of this breed led to the development of tightly controlled breeding programs throughout Hawai‘i. The donkey and mule also established “iconic status” (p. 86) in the important role they played in the history of taro and rice cultivation in Waipi‘o, Waimanu and Pololū Valleys. The horse, donkey and mule trains transported about 1,200 pounds of pa‘i‘ai (cooked, pounded taro) per trip from the valley floors, up steep and windy trails to various kauhale (villages). The authors also shed light on various horse health issues, some general and some unique to Hawai‘i due to “Hawai‘i’s tropical climate, with its high forage moisture, high rainfall and humidity, volcanic soils of variable mineral composition, and common presence of wetlands” (p. 99). Diseases like Big Head Disease, Lampas, Glanders, dental health issues, and hoof and skin issues are prevalent in Hawai’i. Hawai‘i offers unique challenges for horses because “more than three-fourths of these animals live on fibrous, abrasive, [End Page 166] and bulky forage...

Oestrus synchronisation and superovulation alter the cervicovaginal mucus proteome of the ewe

Although essential for artificial insemination (AI) and MOET (multiple ovulation and embryo transfer), oestrus synchronisation and superovulation are associated with increased female reproductive tract mucus production and altered sperm transport. The effects of such breeding practices on the ovine cervicovaginal (CV) mucus proteome have not been detailed. The aim of this study was to qualitatively and quantitatively investigate the Merino CV mucus proteome in naturally cycling (NAT) ewes at oestrus and mid-luteal phase, and quantitatively compare CV oestrus mucus proteomes of NAT, progesterone synchronised (P4) and superovulated (SOV) ewes. Quantitative analysis revealed 60 proteins were more abundant during oestrus and 127 were more abundant during the luteal phase, with 27 oestrus specific and 40 luteal specific proteins identified. The oestrus proteins most disparate in abundance compared to mid-luteal phase were ceruloplasmin (CP), chitinase-3-like protein 1 (CHI3L1), clusterin (CLU), alkaline phosphatase (ALPL) and mucin-16 (MUC16). Exogenous hormones greatly altered the proteome with 51 and 32 proteins more abundant and 98 and 53 proteins less abundant, in P4 and SOV mucus, respectively when compared to NAT mucus. Investigation of the impact of these proteomic changes on sperm motility and longevity within mucus may help improve sperm transport and fertility following cervical AI. SignificanceThis manuscript is the first to detail the proteome of ovine cervicovaginal mucus using qualitative and quantitative proteomic methods over the oestrous cycle in naturally cycling ewes, and also after application of common oestrus synchronisation and superovulation practices. The investigation of the mucus proteome throughout both the follicular and luteal periods of the oestrous cycle, and also after oestrous synchronisation and superovulation provides information about the endocrine control and the effects that exogenous hormones have on protein expression in the female reproductive tract. This information contributes to the field by providing important information on the changes that occur to the cervicovaginal mucus proteome after use of exogenous hormones in controlled breeding programs, which are commonly used on farm and also in a research setting.

Oestrus synchronisation and superovulation alter the production and biochemical constituents of ovine cervicovaginal mucus

Controlled breeding programmes utilising exogenous hormones are common in the Australian sheep industry, however the effects of such programmes on cervicovaginal mucus properties are lacking. As such, the aim of this study was to investigate cervicovaginal (CV) mucus from naturally cycling (NAT), progesterone synchronised (P4), prostaglandin synchronised (PGF2α), and superovulated (SOV) Merino ewes. Experiment 1; volume, colour, spinnbarkeit, chemical profile and protein concentration of mucus (NAT, P4, PGF2α and SOV; n=5 ewes/treatment) during the follicular (5 d) and luteal phases (8 d) was investigated. Experiment 2; in vivo mucus pH and in vitro mucus penetration by frozen-thawed spermatozoa (NAT, P4 and SOV; n=11 ewes/treatment) was investigated over oestrus (2 d) and the mid-luteal phase (pH only, 2 d). Oestrus mucus was more abundant, clearer in colour and less proteinaceous than luteal phase mucus (p<0.05). SOV increased mucus production and protein concentration (p<0.05) while PGF2α reduced mucus volume (p<0.05). Mucus pH (oestrus 6.2–6.5), chemical profile and mucus penetration by sperm were unchanged (p>0.05). Results indicate that exogenous hormones used for controlled breeding affect cervicovaginal mucus production, but few other tested characteristics. Further research is required to explain fertility differences between synchronised and naturally cycling animals following cervical AI.

Holstein Friesian genetic introgression and its association with estimated breeding values and expected producing ability in Karan Fries cattle

Introgression levels inform us about the admixture of genes within the genome of 2 populations due to crossing among them. The present investigation was carried out to determine the introgression levels of Holstein Friesian (HF) into crossbred Karan Fries (KF) cattle, developed under controlled breeding programme at National Dairy Research Institute (NDRI), Karnal, India. The association of HF introgression levels with estimated breeding values (EBVs) and expected producing ability (EPA) of KF cattle were also estimated. Eighteen reported microsatellitemarkers were used in the study and the HF introgression levels were assessed through STRUCTURE 2.3.4 program. Inheritance percentages of HF in the studied KF cattle showed varying degree of levels ranged between 50 and 75%. The results showed that the average HF introgression per cent in KF cattle was 52.30% ranging from 15.96 to 87.21%. The EBV and EPA showed significant association with increasing HF introgression levels. However, HF inheritance levels had nonsignificant effect on those traits. Introgression levels may be the future tool for explaining the productive performances of crossbreds than inheritance levels.

Biomass production and potential ethanol yields of shrub willow hybrids and native willow accessions after a single 3-year harvest cycle on marginal lands in central Minnesota, USA

Short rotation woody crops are being developed as a sustainable source of biomass for the production of bioenergy, biofuels, and bioproducts. With the potential increase in demand of biomass for energy in the future, there is a need to diversify and expand its source. In the present study, we evaluated the growth performance, biomass production, energy content, and potential ethanol yields of shrub willow hybrids and native willow accessions. Shrub willow hybrids cuttings were obtained from the State University of New York through its controlled breeding program while cuttings used for native willow accessions were collected naturally. At the end of one rotation, consisting of three growing seasons, we found that shrub willow hybrids outperformed native willow accession species (P = 0.0004), with an average survival rate of 80 and 39 %, respectively. Biomass production of shrub willow hybrids and native willow accessions ranged from 7.42 to 16.0 and from 0.69 to 1.83 Mg ha−1 oven dry weight, respectively. The chemical composition (mass fraction % on dry basis) of willow hybrids and native willow accessions generally contained 39 % cellulose, 19 % hemicellulose, 25 % lignin, 1.4 % ash content, 17,500–18,500 kJ kg wood−1, and 385 L Mg−1 of theoretical ethanol yield. Energy content and potential ethanol yields on a dry weight basis did not vary between shrub willow hybrids and native willow accessions; however, the amount of biomass produced per unit land area is known to influence potential ethanol yields. Thus, we suggest that shrub willow hybrids offer promising potential as an alternative source of biomass. The results of our study suggest that four of the shrub willow hybrids evaluated have a greater potential for use as biomass energy crops on marginal lands in central Minnesota than the native willow accessions; hence, there is a need to test their potential at a larger scale.

Embryonic development and larval stages of Steindachneridion parahybae (Siluriformes: Pimelodidae): implications for the conservation and rearing of this endangered Neotropical species

Steindachneridion parahybae is a freshwater catfish endemic to the Paraíba do Sul River and is classified as an endangered Neotropical species. An increasing number of conservation biologists are incorporating morphological and physiological research data to help conservation managers in rescue these endangered species. This study investigated the embryonic and larval development of S. parahybae in captivity, with emphasis in major events during the ontogeny of S. parahybae. Broodstocks were artificially induced to reproduce, and the extrusion occurred 200-255 degree-hours after hormonal induction at 24°C. Larval ontogeny was evaluated every 10 minutes under microscopic/stereomicroscopic using fresh eggs samples. The main embryogenic development stages were identified: zygote, cleavage, including the morula, blastula, gastrula phase, organogenesis, and hatching. The extruded oocytes showed an average diameter of 1.10 ± 0.10 mm, and after fertilization and hydration of eggs, the average diameter of eggs increased to about 1.90 ± 0.60 mm, characterized by a large perivitelline space that persisted up to embryo development, the double chorion, and the poles (animal and vegetative). Cell division started about 2 minutes after fertilization (AF), resulting in 2, 4, 8 (4 x 2 arrangement of cells), 16 (4 x 4), 32 (4 x 8) and 64 (2 x 4 x 8) cells. Furthermore, the blastula and gastrula stages followed after these cells divisions. The closed blastopore occurred at 11 h 20 min AF; following the development, the organogenetic stages were identified and subdivided respectively in: early segmentation phase and late segmentation phase. In the early segmentation phase, there was the establishment of the embryonic axis, and it was possible to distinguish between the cephalic and caudal regions; somites, and the optic vesicles developed about 20 h AF. Total hatching occurred at 54 h AF, and the larvae average length was 4.30 ± 0.70 mm. Gradual yolk sac reduction was observed during the first two days of larval development. The first feeding occurred at the end of the second day. During the larval phase, cannibalism, heterogeneous larval growth and photophobia were also observed. This information will be important in improving the artificial reproduction protocols of S. parahybae in controlled breeding programs.

Association between leptin single nucleotide polymorphism and reproductive performance of lactating Holstein cows

The objectives of the current study were to evaluate the associations among reproductive performance of Holstein cows, single nucleotide polymorphism (SNP) in the R4C locus of the Exon-2 region of the leptin gene and health disorders. Lactating dairy cows ( n = 814) had their DNA sequenced at the Exon-2 region of the leptin gene to determine the presence of SNP in the R4C locus. Cows had the stage of estrous cycle synchronized with two injections of PGF 2α 14 d apart, with or without a progesterone insert. After the second PGF 2α, cows were either inseminated on detected estrus and, if not inseminated within 13 d, cows were submitted to a timed artificial insemination (AI) protocol 13 d after the second PGF 2α. Blood was sampled at 35 ± 3, 49 ± 3, and 62 ± 3 d in milk (DIM) and cows with progesterone <1.0 ng/mL in the first two samples were considered to be anovular, whereas those with at least one of the first two samples with progesterone ≥1.0 ng/mL were considered to have initiated estrous cyclicity. Anovular cows with progesterone ≥1.0 ng/mL at 62 ± 3 DIM were considered to have resumed estrous cyclicity. Pregnancy was diagnosed at 31 and 60 d after first postpartum AI and at 42 d after subsequent inseminations. Resulting genotypes were CC (34.6%), CT (48.2%), and TT (17.2%). Leptin genotype was associated ( P = 0.03) with increased prevalence of estrous cyclic cows at 49 ± 3 DIM, as TT cows were and tended to be less likely to be estrous cyclic than CC and CT cows, respectively. Other measures of reproductive performance in the first 305 DIM were not associated with leptin genotype. Cows diagnosed with at least one postparturient disease were less likely to become pregnant after first ( P < 0.01) and second ( P = 0.02) AI and to be pregnant at 305 DIM ( P < 0.01). Furthermore, cows diagnosed with a disease event had a 36% reduction ( P < 0.001) in the rate of pregnancy, which extended the median interval to pregnancy by 60 d. Estrous cyclic cows had a 35% increased rate of pregnancy, which reduced the interval to pregnancy by 34 d. Cows homozygous for the T allele were less likely to be cyclic early postpartum, but leptin genotype was not associated with other reproductive responses when cows were subjected to a controlled breeding program.

The effect of intra-uterine devices on the reproductive physiology and behaviour of pony mares

Spherical (35 mm diameter) glass intra-uterine devices (IUDs) are commonly understood to modify sexual behaviour in performance mares. The effect of IUDs on the endocrinology (luteinising hormone, oestradiol, progesterone, testosterone), ovarian and uterine function, sexual and social behaviours associated with the ovarian cycle were evaluated during the natural breeding season in nine, nuliparous pony mares (4.6±0.5 years old, 230±12 kg bodyweight). Age and weight-matched groups were allocated to sham-treatment (n=5) or IUD-implantation (n=4) groups. Fifty complete ovarian cycles were evaluated, with 26 ovarian cycles monitored for the nine mares prior to treatment and a further 12 cycles were evaluated for mares in each of the groups post-treatment. Detailed characterisation of cyclic reproductive changes in the pony may be of value for controlled breeding programmes. The presence of an IUD was well-tolerated, but failed to modify any recorded aspect of reproductive physiology or behaviour.

Fertility in high-producing dairy cows: Reasons for decline and corrective strategies for sustainable improvement

The fertility of dairy cows has declined worldwide and this change is surprising given the importance of good fertility to the dairy industry. The decline in fertility can be explained by management changes within the dairy industry and also negative genetic correlations between milk production and reproduction. Four primary mechanisms that depress fertility in lactating cows are anovulatory and behavioral anestrus (failure to cycle and display estrus), suboptimal and irregular estrous cyclicity (this category includes ovarian disease and subnormal luteal function after breeding), abnormal preimplantation embryo development (may be secondary to poor oocyte quality), and uterine/placental incompetence. The solution for improving fertility in high-producing dairy cows will include both short-term and long-terms components. For the immediate short-term, using high fertility sires and implementing controlled breeding programs will help. Controlled breeding programs improve reproductive efficiency in confinement-style dairy herds and can be combined with post-insemination treatments to enhance fertility. An additional immediate short-term solution involves changing the diet so that dietary ingredients invoke hormonal responses that benefit the reproduction of the cow. The short-term solutions described above do not address the fundamental need for correcting the underlying genetics for reproduction in high-producing dairy cows. Crossbreeding will improve reproductive performance perhaps because it alleviates inbreeding and also lowers production in cows with an extreme high milk production phenotype. The current crisis in dairy reproduction will be permanently solved, however, when the genetics for dairy reproduction are improved through a balanced genetic selection strategy.

Genetic characterization of Italian honeybees,Apis mellifera ligustica, based on microsatellite DNA polymorphisms

The genetic variability of Apis mellifera ligustica was screened throughout the Italian peninsula and Sardinia with eight polymorphic microsatellite loci. Samples of Apis mellifera mellifera, Apis mellifera carnica and from the Buckfast breeding line were genotyped for comparison. Low Fis and Fst values suggest the absence of genetic structure within and among A. m. ligustica populations, although the high number of alleles detected and heterozygosity. Phylogenetic and individual analyses confirmed that A. m. ligustica has come to resemble one large population, probably as a result of intensive beekeeping practices such as migratory beekeeping and large-scale commercial queen trading. Since the introgression of foreign alleles into both endemic natural and commercial A. m. ligustica populations, can be detected and monitored by microsatellite analysis, the results provide a reference data set for future local biodiversity conservation and other controlled breeding programs.

A computational approach to animal breeding

We propose a computational model of mating strategies for controlled animal breeding programs. A mating strategy in a controlled breeding program is a heuristic with some optimization criteria as a goal. Thus, it is appropriate to use the computational tools available for analysis of optimization heuristics. In this paper, we propose the first discrete model of the controlled animal breeding problem and analyse heuristics for two possible objectives: (1) breeding for maximum diversity and (2) breeding a target individual. These two goals are representative of conservation biology and agricultural livestock management, respectively. We evaluate several mating strategies and provide upper and lower bounds for the expected number of matings. While the population parameters may vary and can change the actual number of matings for a particular strategy, the order of magnitude of the number of expected matings and the relative competitiveness of the mating heuristics remains the same. Thus, our simple discrete model of the animal breeding problem provides a novel viable and robust approach to designing and comparing breeding strategies in captive populations.

Veterinary clinical application of GnRH—questions of efficacy

The efficacy of GnRH treatments are reviewed in relation to prevention of embryo mortality, control of follicle development in synchronization programmes using PG as luteolysin, induction of ovulation in post-partum anoestrus and in bovine cystic ovarian disease. It is suggested that in cattle that GnRH is effective in increasing pregnancy rates when given either at the time of insemination (first or repeat) or between days 11 and 14 after insemination. Evidence is also presented for positive effects on pregnancy rates in sheep, mares and sows. Use of GnRH as an integral part of synchronising regimens where it is given 7 days before PG and then again 48–60 h after PG appears to be effective in increasing the synchrony of ovulation in controlled breeding programmes. The main synchronizing effect seems to reside in the second GnRH injection whereas the importance of the first is in prolonging the luteal phase in those cows treated late in the cycle. The published work on the potential use of GnRH to induce ovulation in anovulatory cattle is reviewed. Neither bolus dose injections, pulsatile, continuous infusion, nor controlled release formulations of GnRH, have yet proved effective in inducing fertile ovulations in a predictable or consistent manner. It is suggested that this is due to the variability of follicular status when treatment is initiated. GnRH is commonly used in the treatment of bovine cystic ovarian disease. However, although stimulating ovulation/luteinisation of a new follicle and luteinisation of the cyst, fertility of treated cattle remains very poor and it is suggested that a better understanding of the disease is needed before more effective treatments can be developed.