Effects of supplementation with docosahexaenoic acid on reproduction of dairy cows.

The objectives were to determine the effects of supplementing docosahexaenoic acid (DHA)-rich algae on reproduction of dairy cows. Holstein cows were assigned randomly to either a control ( = 373) or the same diet supplemented daily with 100 g/cow of an algae product containing 10% DHA (algae,  = 366) from 27 to 147 days postpartum. Measurements included yields of milk and milk components, fatty acids (FA) profiles in milk fat and plasma phospholipids, resumption of ovulation by 57 days postpartum, pregnancy per artificial insemination (AI) and expression of interferon-stimulated genes in leukocytes.

Comparison of bioactivities, binding properties and intrafollicular levels of bovine follistatins.

Five isoforms of follistatin (FST) (Mr 31, 33, 35, 37, and 41  kDa) were purified from bovine follicular fluid (bFF). Comparison of their activin and heparan sulphate proteoglycan (HSP) binding properties and biopotencies in the neutralisation of activin A action in vitro revealed that all five isoforms bound activin A, but they did so with different affinities. Only the 31  kDa isoform (FST-288) bound to HSP.

Linkage mapping of the locus for inherited ovine arthrogryposis (IOA) to sheep chromosome 5.

Arthrogryposis is a congenital malformation affecting the limbs of newborn animals and infants. Previous work has demonstrated that inherited ovine arthrogryposis (IOA) has an autosomal recessive mode of inheritance. Two affected homozygous recessive (art/art) Suffolk rams were used as founders for a backcross pedigree of half-sib families segregating the IOA trait.

Comparisons between nulliparous heifers and cows as oocyte donors for embryo production in vitro.

The aims of the present study were to compare (1) Holstein-Friesian heifers versus early postpartum lactating cows, and (2) different age categories of crossbred beef heifers versus cows, in terms of oocyte yield, morphological quality and developmental competence. Four experiments were designed to test the associated hypotheses. In Experiment 1, ovum pick up was carried out twice weekly for a period of 5 weeks on Holstein-Friesian heifers (n = 8) and early postpartum cows (n = 8).

Species-related differences in blastocyst quality are associated with differences in relative mRNA transcription.

The objective of this study was to compare the relative transcript abundance of several important candidate genes between ovine and bovine blastocysts. Blastocysts were produced by in vitro maturation, fertilization, and subsequent culture in one of two formulations of synthetic oviduct fluid medium (SOF1 and SOF2). From each IVF replicate groups of 10 bovine and 10 ovine blastocysts from each of the two media were used for analysis of mRNA relative abundance.

Effect of the post-fertilization culture environment on the incidence of chromosome aberrations in bovine blastocysts.

We have previously shown that the postfertilization embryo culture environment has a significant influence on the quality of the resulting bovine blastocyst measured in terms of its cryotolerance and relative abundance for several developmentally important gene transcripts. Using three different culture conditions known to produce blastocysts of differing quality, the objective of this study was to examine whether the postfertilization culture environment had an effect on the incidence of mixoploidy in bovine blastocysts. Presumptive zygotes, produced by in vitro maturation and fertilization, were cultured in vitro in synthetic oviduct fluid (SOF) medium in the absence or presence of fetal calf serum (FCS), or in vivo in the ewe oviduct.

The effect of eCG or estradiol at or after norgestomet removal on follicular dynamics, estrus and ovulation in early post-partum beef cows nursing calves.

In post-partum anestrous beef cows suckling calves, neither the choice of hormonal regime to ensure the presence of a healthy dominant follicle at the end of a progestagen treatment nor the optimum hormone to induce estrus and ovulation is clear. Twenty-eight beef cows, in good body condition, 25-30 days post-partum, were assigned to one of four treatments: (i) 3mg norgestomet (N) implant with 5mg estradiol valerate (EDV) and 3mg N injection at the time of insertion (Crestar) for 5 days followed by 600 IU eCG at the time of implant removal; (ii) Crestar for 5 days as in (i) followed by 0.75 mg estradiol benzoate (EDB) 24h later; (iii) Crestar for 9 days followed by 600 IU eCG at the time of implant removal; and (iv) Crestar for 9 days followed by 0.

Analysis of differential maternal mRNA expression in developmentally competent and incompetent bovine two-cell embryos.

The main objective of this study was to identify mRNA transcripts associated with embryonic developmental competence. In cattle, mRNA transcripts, ribosomes, and proteins accumulated during the growth phase are drawn on to sustain maturation, fertilization, and the initial cell cycle divisions up to the 8- to 16-cell stage. Early cleaving mammalian zygotes are more likely to develop to the blastocyst stage than their later cleaving counterparts, thus reflecting the intrinsic quality of the oocytes from which they originated.

Search for the bovine homolog of the murine ped gene and characterization of its messenger RNA expression during bovine preimplantation development.

In mice, a gene (Ped: preimplantation embryo development) that regulates preimplantation embryonic growth, including cleavage rate and embryo survivability, has been described. The objective of the current study was to identify the bovine homolog of the Ped gene and to characterize the mRNA expression pattern of this gene during bovine preimplantation embryo development. The NCBI GenBank/EBI expressed sequence tags (EST) databases were searched for bovine ESTs that were homologous to the murine Ped gene, and the resulting ESTs were aligned and assembled into a contiguous sequence.

Relative messenger RNA abundance in bovine oocytes collected in vitro or in vivo before and 20 hr after the preovulatory luteinizing hormone surge.

In the cyclic cow, final maturation of the ovulatory follicle is initiated by the preovulatory luteinizing hormone (LH) surge. During the subsequent 24 hr period, the oocyte nucleus undergoes meiotic progression to metaphase II and several changes in cytoplasmic organization take place. We have previously shown that oocytes recovered at the time of the LH peak and matured in vitro are less competent to reach the blastocyst stage than their counterparts recovered 20 hr later following in vivo maturation, despite both groups undergoing IVF and culture in parallel.

Developmental, qualitative, and ultrastructural differences between ovine and bovine embryos produced in vivo or in vitro.

The objective of this study was to compare bovine and ovine oocytes in terms of (1) developmental rates following maturation, fertilization, and culture in vitro, (2) the quality of blastocysts produced in vitro, assessed in terms of their ability to undergo cryopreservation, and (3) the ultrastructural morphology of these blastocysts. In vitro blastocysts were produced following oocyte maturation/fertilization and culture of presumptive zygotes in synthetic oviduct fluid. In vivo blastocysts were used as a control from both species.

Consequences of bovine oocyte maturation, fertilization or early embryo development in vitro versus in vivo: implications for blastocyst yield and blastocyst quality.

The aim of this study is to examine the effect of bovine oocyte maturation, fertilization or culture in vivo or in vitro on the proportion of oocytes reaching the blastocyst stage, and on blastocyst quality as measured by survival following vitrification. In Experiment 1, 4 groups of oocytes were used: (1) immature oocytes from 2-6 mm follicles; (2) immature oocytes from > 6 mm follicles; (3) immature oocytes recovered in vivo just before the LH surge; and (4) in vivo matured oocytes. Significantly more blastocysts developed from oocytes matured in vivo than those recovered just before the LH surge or than oocytes from 2-6 mm follicles.