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38 Cards in this Set
- Front
- Back
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when is the onset of puberty for cattle?
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8-19mo
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when is the onset of puberty for sheep?
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6-9mo
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what must you consider in onset of puberty?
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species and breed variation and interation of environment, nutrition, genetics
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what are the changes in LH associated with puberty in heifers?
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before puberty, low LH, during puberty a rise in LH, then routine spikes in LH
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what are the effects of energy level on age and weight at puberty?
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pushing energy in the feed ration may enable a better plain of nutrition that may make puberty occur earlier which is reliant on age and weight (thus feed)
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what is the cycle length in cattle?
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21d (17-24)
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what is the estrus in cattle?
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15h (6-24)
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when is the onset of estrus to ovulation in cattle?
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24-32h
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what is the cycle length in sheep?
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17d (13-19)
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what is the estrus in sheep?
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30h (18-48)
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what is the onset of estrus to ovulation in sheep?
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24-30h
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what are the behavioral signs of estrus in sheep?
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short periods of restlessness, urinationin presence ofa ram, immobile stance
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what are the behavioral signs of estrus in cattle?
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cows will mount each other with the mounted cow in estrus
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what is the length of gestation for cows?
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282 days (9mo)
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what is the length off gestation for ewes?
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150 days (5mo)
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what occurs with fetus development?
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exponential rate of growth, 50% during last 60d (cattle), developmental landmarks
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what occurs with the placenta?
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cotyledonary, placentome = fetal cotyledon and maternal caruncle
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how many cotyledons does a sheep have?
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90-100
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how many cotyledons does a cow have?
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70-120
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how does maternal recognition of pregnancy occur?
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conceptus signals the mother of its presence before onset of luteolysis, and prevents it from occurring, the antiluteolytic prevents or blocks luteolysis that blocks PGF release and the luteotropics stimulate the CL to continue to function even in the face of PGF via PGE
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when does maternal recognition of pregnancy occur for cattle?
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15-17d due to bovine trophoblastic protein (bTP-1)
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when does maternal recognition of pregnancy occur for sheep?
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12-14d due to ovine trophoblastic protein (oTP-1)
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what are the progesterone requirements of sheep for the ovary (CL) and fetal membranes?
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first 50-60days, then last 100 days
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what are the progesterone requirements of cattle for the ovary (CL) and fetal membranes?
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first 200-250d, some esp after d200
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what are the estrogen requirements of sheep for the ovary (follicle) and the fetal membranes?
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produced not required, required throughout
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what are the estrogen requirements of cattle for the ovary (follicle) and the fetal membranes?
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produced not required, required throughout
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what are the stages of parturition?
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stage 1 (preliminary), stage 2 (expulsion of the fetus), stage 3 (expulsion of fetal membranes)
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what occurs during stage 1 preliminary parturition?
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uterine contractions move from irregular to regular, rotation of fetus, dilation of the cervix by relaxin & collagenase, relaxation of the pubic symphysis by relaxin, chorioallantois ruptures for lubrication
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what occurs during stage 2 expulsion of the fetus?
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fetus inside amnion forced through birth canal by active abdominal and uterine contractions and oxytocin, rupture of amnion, delivery of fetus
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what occurs during stage 3 expulsion of fetal membranes?
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chorionic villi loosen and 'detach', afterbirth is shed
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what is the average time of the 3 stages of parturition for cows?
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(1) 2-6h, (2) 0.5-1h, (3) 2-12h
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what is the average time of the 3 stages of parturition for ewes?
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(1) 2-6h, (2) 0.5-2h, (3) 5-8h
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what is uterine involution?
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transformation from pregnant to nonpregnant size via shrinkage, muscle tone, blood flow, epithelial lining sloughing regressing lochia (discharge) and regrowth all completed in 30-40d
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what occurs postpartum?
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uterine involution and changes in the cervix, energy balance, endocrine status, suckling effects, resumption of estrous cycles
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what affects the resumption of estrous cycles?
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nutrition needs energy balance (early postpartum EB negative and magnitude of negative EB is critical), parity (primiparous longer than multiparous), season (cattle - summer subfertility, sheep - anestrous season), peripartum and postpartum diseases, species and breed, social interaction - often mediated by pheromones
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what impacts seasonal gonadal activity in sheep?
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photoperiod correlates to % sheep cycling
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how do social interactions affect resumption of estrous in sheep?
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ram effect - exposure of seasonally anestrous ewes during the transition period (late summer) to a ram causes an increase in LH and induces cyclicity
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how do social interactions affect resumption of estrous in cattle?
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bull effect - exposure of peripubertal heifers or postpartum suckled beef cows to bull causes earlier cyclicity
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