Interrelationships between energy balance and postpartum reproductive function in dairy cattle.

This research was carried out to define in vitro conditions that would enable ejaculated rabbit sperm to fertilize ova in vitro. During 20 mm exposure of sperm cells to defined media of increasing NaCI concentrations, progressive removal or alteration of sperm surface seminal plasma antigenic components was initiated and completed as reflected by an immunological assay at approximately 300 and 380 mOsm/kg, respectively. Hypertonic (380 mOsm/kg) medium effected complete removal or alteration of these components as determined by the immunological assay during the first 5 mm of sperm treatment. Isotonic (305 mOsm/kg) treatment was shown to have effected removal or alteration of some but not all of the antigenic sperm coating seminal plasma components detectable by this means during 20 mm of exposure. Sperm within the perivitelline apace, presence of pronuclei. and 2- and 4-cell cleavage stages were taken as evidence for fertilization. None of 34 ova incubated for 27 h in vitro with once-washed sperm showed evidence of fertilization. Following treatment of sperm with hypertonic (380 mOsm/kg) medium prior to in vitro insemination, proportions of ova showing evidence of fertilization ranged from 8.1 percent (12 to 148 ova) to 72.2 percent (52 of 72 ova); and, following treatment of sperm with isotonic (305 mOsm/kg) medium, fertilization of ova ranged from 0 percent (0 to 19 ova) to 73.9 percent (SI of 69 ova) when results were considered according to individual male sperm donors. No large differences were found by the immunological assay that could be linked to variability of fertilizing ability of sperm from different bucks. Differences in metabolic characteristics of sperm cells was suggested as a likely reason for differences in fertilizing ability of sperm from different bucks. In experiments using sperm and ova from the same sources, no differences in fertilization results were apparent following 305 and 380 mOsm/kg sperm treatments, Initiation, but not completion, of removal or alteration of sperm surface seminal plasma antigenic components, then, was a necessary prerequisite to in vitro insemination for successful achievement of fertilization in vitro. Sperm penetration into ova occurred in some cases before 7-10 h after insemination (4 of 54 ova penetrated), but actively motile sperm were found within the perivitelline apace of other ova as late as 25 h after insemination. One hundred and seventy-six 2- and 4-cell stage embryos were transferred to 14 recipient does. Twenty-four embryos (13.1 percent) implanted in 6 recipients but most were resorbed. Three embryos resulting from in vitro fertilization with in vitro capacitated ejaculated rabbit sperm were carried successfully to term by 2 recipients and 2 of the offspring were males. This provides documentation for the authenticity of in vitro capacitation of ejaculated sperm of a mammalian species and represents the initial successful combination of in vitro sperm capacitation with in vitro fertilization and embryo transfer in the rabbit.

Capacitation of Rabbit Spermatozoa in vitro

Pregnancy, decreased feed intake during late gestation, lactogenesis, and parturition have dramatic effects on metabolism in dairy cows during the transition period from 3 wk before calving to 3 wk after calving. Increases in plasma NEFA occur during the 10 d before calving and may precede the decrease in feed intake. Plasma NEFA concentrations are highest at calving and decrease rapidly after calving. Plasma glucose concentration decreases during the transition period except for a transient increase associated with calving. Hepatic glycogen is reduced and lipid is increased during the transition period. Feed intake is usually decreased 30 to 35% during the final 3 wk prepartum, but negative energy and protein balances are not as severe as during the week following parturition. Prepartum feed intake is positively correlated to postpartum feed intake; therefore, efforts to maximize feed intake should begin before calving. Overconditioned cows may be more susceptible to a prepartum decrease in feed intake. Increasing nutrient density of the diet during the transition period may enhance feed intake. Feeding more fermentable carbohydrate during the prepartum transition period may acclimate the microbial population to lactation diets, promote development of ruminal papillae, increase absorptive capacity of the rumen epithelium, and reduce lipolysis by delivering more glucogenic precursor to the liver and enhancing blood insulin. Supplementing fat to transition diets does not seem to alleviate health problems associated with negative energy balance. Enhancing amino acid absorption by the prepartum cow may improve lactation performance and health, although mechanisms of action have not been identified.

https://webpages.uidaho.edu/ruminant_nutrition/reading materials 511/nutrient metabolism/nutrinet metabolism- grummer 1995.pdf

Impact of changes in organic nutrient metabolism on feeding the transition dairy cow.

It isnot clearwhether the turnover of ovarianfollicles during the estrouscycle in cattleisContinuous and independent of thephase of the cycle,or whether waves of follicular growth occur at specifictimes of the cycle. To clarifythis controversy, the pattern of growth and regression of ovarian follicles was characterized during a complete estrous cycle in ten heifers by daily ultrasonographic examinations. Follicles � 5 mm were measured and theirrelativelocationswithin the ovary were determined in order tofollow the sequentialdevelopment of each individual follicle. Results indicated the presence of either two (n = 2 heifers), three (n = 7), or four (n = I) waves of follicular growth per cycle.Each wave was characterizedby the development of one large (dominant) follicle and a variable number of smaller (non-dominant) follicles. In the most common pattern observed (threewaves/cycle),thefirst, second, and third waves started on Days 1.9 ± 0.3, 9.4 ± 0.5, and 16.1 ± 0.7 (X ± SEM), respectively. The dominant follicle in the third wave was the ovulatory follicle. The maximal sizeand the growth rateof the dominant folliclein the second wave were significantlylower than inthe other waves, but no significant difference was observed between the first and third waves. For the two heifers that had two follicularwaves/cycle,the waves startedon Days 2 and 11, whereas in the remaining heifer (four waves/cycle), the waves began on Days 2, 8, 14, and 17, respectively. At 0, 1, 2, 3, and 4 days before estrus, the ovulatory follicle was the largest follicle in the ovaries in 100%, 95%, 74%, 35%, and25% offollicular phases monitored, respectively. The relative size of the preovulatory follicle at the completion of luteolysis (progesterone< I ng/ml) was negatively correlated (r = -0.90; p<0.0001) with the interval of time between the end of luteolysis and the luteinizinghormone surge,suggestingthat the length of proestrus isdetermined by the sizeof thepreovulatoryfollicleat the beginning ofproestrus.In conclusion,thisstudy shows thatthe development of ovarian follicles�5 mm in heifers occurs inwaves and thatthe most common pattern isthreewaves per estrouscycle.

/pdf/ovarian-follicular-dynamics-during-the-estrous-cycle-in-3zhq139zsl.pdf

Ovarian follicular dynamics during the estrous cycle in heifers monitored by real-time ultrasonography.

The spermatozoa of most invertebrates (e.g., sea urchins) and nonmammalian vertebrates (e.g., fishes and amphibians) have full capacity to fertilize eggs upon leaving the testis. Testicular spermatozoa of mammals, on the other hand, do not possess the ability to do so. Their fertilizing capacity develops as they pass through the epididymis (Young, 1931; Nishikawa and Waide, 1952; Blandau and Rumery, 1964; Bedford, 1966; Orgebin-Crist, 1967). This process, apparently “unique” to mammals, is referred to as the epididymal maturation of spermatozoa. Even after their maturation, however, spermatozoa require an additional phase of maturation or capacitation within the female genital tract before they are able to fertilize eggs (Austin, 1951, 1952; Chang, 1951a). Thus, epididymal maturation and capacitation are two extra steps that mammaliam spermatozoa must take before they can effect fertilization. In this chapter, I will discuss how mammalian spermatozoa prepare themselves for fertilization and how the spermatozoa and eggs interact during fertilization. The process and mechanisms of sperm transport in the female genital tract will not be dealt with extensively here. Readers are referred to Bishop (1961, 1969), Blandau (1969), Bedford (1970b, 1972b), Thibault (1972, 1973a), Zamboni (1972), Blandau and Gaddum-Rosse (1974), Hafez and Thibault (1975), Overstreet and Katz (1977), Overstreet and Cooper (1978, 1979b), Overstreet et al. (1978), Shalgi and Kraicer(1978), Cooper et al. (1979) and Hunter (1975, 1980). The rejection or elimination of extra spermatozoa by the fertilized egg, one of the most fascinating events in fertilization, will not be discussed here. Instead, readers are referred to the chapter by Dr. Wolf in this volume. The physiology of egg activation has been described and discussed to some extent by Gwatkin (1977) and Yanagimachi (1978a). There are numerous reviews dealing with general aspects of mammalian fertilization. The following are recommended to aid in grasping the outline of mammalian fertilization: Austin and Bishop (1957), Austin and Walton (1960), Austin (1961, 1968), Blandau (1961), Piko (1969), Thibault (1969), Bedford (1970a,b, 1972b), Gwatkin (1976, 1977), Yanagimachi (1977, 1978a), Bedford and Cooper (1978) and Hunter (1980).

Mechanisms of Fertilization in Mammals

Analysis of repeated measurements of animals.

Bovine serum estrogens, progestins and glucocorticoids during late pregnancy parturition and early lactation.

Holstein cows were assigned at calving to be (1) milked at 12-hr (n = 5) or (2) 6-hr (n =5) intervals or (3) suckled ad libitum by one calf and milked at 12-hr intervals (n = 6). Suckling resulted in an increase in the postpartum (PP) interval to first ovulation (39.7 vs 21.2 days), but increased milking frequency did not. Delayed resumption of episodic luteinizing hormone (LH) secretion was associated with the increased PP interval to ovulation in suckled cows. Both frequency and amplitude of episodic LH peaks were reduced (P less than .05) on days 7 and 14 PP in suckled cows compared to nonsuckled cows (1.2 vs 2.5 peaks/4.5 hr and 1.8 vs 2.8 ng/ml, respectively). Suckling did not significantly modify basal of milking-induced concentrations of prolactin or total glucocorticoids. Nor did serum concentrations of progesterone or estradiol-17 beta differ between suckled and nonsuckled cows, or between day 7 and day 14 PP. Milking-induced secretion of both prolactin and total glucocorticoids were greater (P less than .05) on day 14 PP than on day 7 PP in both suckled and nonsuckled cows. These results suggest that suckling may delay the first PP ovulation by suppressing episodic LH secretion. Alternations in prolactin, total glucocorticoids, progesterone or estradiol-17 beta do not apper to mediate directly the effects of suckling on PP episodic LH secretion and (or) ovulation.

Suckling and Four-Times Daily Milking: Influence on Ovulation, Estrus and Serum Luteinizing Hormone, Glucocorticoids and Prolactin in Postpartum Holsteins

Estradiol and progesterone in blood serum during the bovine estrous cycle.

SummaryPGF2α (30 mg Tham salt) was injected im into five heifers during diestrus (Days 9 to 13 of the estrous cycle), im into six heifers during metestrus (Day 3), and intravaginally into six heifers during diestrus. After im PGF2α during diestrus, (a) luteal diameter decreased from 2.3 ± 0.1 cm to 1.8 ± 0.1 cm at 24 hr and to 0.6 ± 0.3 cm at 72 hr, (b) blood serum progesterone fell from 4.0 ± 0.4 ng/ml to 1.5 ± 0.2 ng/ml at 12 hr and to 1.0 ± 0.2 ng/ml at 72 hr, and (c) estrus began at 74 ± 3 hr and ovulation occurred at 104 ± 6 hr. After intravaginal PGF2α during diestrus, one heifer failed to respond; the other five responded similarly to those given im PGF2α during diestrus except that luteolysis was more variable and delayed about 1 or 2 days compared to that after im PGF2α. PGF2α (im) was neither luteolytic nor luteostatic in metestrus. We conclude that 30 mg PGF2α is luteolytic during diestrus in heifers, but im administration is more effective than intravaginal administration.

H. D. Hafs

Papers

Analysis of repeated measurements of animals.

Bovine serum estrogens, progestins and glucocorticoids during late pregnancy parturition and early lactation.

Suckling and Four-Times Daily Milking: Influence on Ovulation, Estrus and Serum Luteinizing Hormone, Glucocorticoids and Prolactin in Postpartum Holsteins

Estradiol and progesterone in blood serum during the bovine estrous cycle.

Progesterone, LH, estrus and ovulation after prostaglandin F 2 in heifers.