Progesterone status, parity, body condition, and days postpartum before estrus or ovulation synchronization in suckled beef cattle influence artificial insemination pregnancy outcomes1

Abstract

Our objective was to assess the effects of progesterone before initiating an estrus- or ovulation-synchronization program in addition to the influence of parity, BCS, and days postpartum on resulting pregnancy rates per AI. Experimental data were combined from 73 herd-year studies consisting of more than 8,500 suckled beef cows exposed to variants of the CO-Synch program. Blood was harvested from samples collected at 10 and 0 d before the onset of CO-Synch, and progesterone concentrations of the samples were determined. The progesterone environment preceding synchronization was assessed in 3 ways on the basis of progesterone concentrations measured in the 2 defined blood samples. All binomial logistic regression models used procedure GLIMMIX in SAS and included the fixed effects of program duration, inclusion of progesterone via an intravaginal insert, parity, days postpartum at AI, BCS, and appropriate interactions. In addition, model 1 included 3 categories of progesterone concentrations (low [<1 ng/mL], medium [1.00 to 3.99 ng/mL], and high [≥4.00 ng/mL] concentrations) at 10 and 0 d before synchronization and their interaction. Model 2 included 4 categories defining the stage of the estrous cycle (late diestrus, early diestrus, and proestrus-estrus-metestrus) or anestrus, at which cows started the synchronization program. Model 3 defined cows as cycling or noncycling at the onset of the program. Significant effects of progesterone supplementation, which hormone was used to initiate the timed AI program, parity, BCS, days postpartum, and progesterone status assessed in 3 ways were consistent in nearly all models. Progesterone status at the onset of synchronization was not important to pregnancy outcomes in multiparous cows, whereas pregnancy rate per AI was suppressed in primiparous cows that began in a low-progesterone environment (proestrus, estrus, metestrus, or anestrus). A significant 3-way interaction of parity, BCS, and days postpartum in 2 models reinforced the importance of these factors to AI pregnancy outcomes. Ancillary analyses identified the significant effects of cycling status and BCS as well as days postpartum on luteolytic response to PGF(2α). Pregnancy loss of 2.7% to 4.2% was detected to occur between a positive pregnancy diagnosis at 35 d post-AI and later stages of pregnancy. We concluded that progesterone status at the onset of the synchronization program is critical to pregnancy outcomes in primiparous but not multiparous cows.

Short communication: Test for nonpregnancy in dairy cows based on plasma progesterone concentrations before and after timed artificial insemination

“…The P/AI for responding cows (59.3%) demonstrates that lactating cows in confinement dairies with the correct response to timed AI treatment have P/AI that approaches 60%. This level of fertility is similar to or better than what is reported for Holstein heifers that were AI after estrus (Lopes et al, 2013) as well as postpartum beef cattle (Stevenson et al, 2015). The result suggests that a major cause of infertility in lactating dairy cows is abnormal ovarian function within a few days of AI.…”

Effect of a second treatment of prostaglandin F2α during the Ovsynch program on fixed‐time artificial insemination conception rates and luteolysis in split‐calving, pasture‐fed dairy cows

“…Differences in progesterone concentrations across studies are likely to be due to the use of different assays (e.g. chemiluminescence in this study versus radioimmunoassay in others), differences in the proportion of cows in post‐partum anoestrus at the start of treatment programs and differences between beef and dairy cows . Although P4 a cutoff of <1 ng/mL has been used in other studies to classify cows as having undergone luteolysis, in our data, there appears to be a distinct cut‐off point of 3 ng/mL at the time of AI in the OV group (Figure ) and a cut‐off point of 2 ng/mL at the time of AI in the MO group (Figure ).…”

Hemocytopoiesis of functionally active newborn calves and calves in the state of hypoxia

“…А. А. Zamaziy Hemocytopoiesis of functionally active newborn calves and calves in the state of hypoxia Вступ В умовах недостатнього забезпечення тканин оксигеном для задоволення потреб метаболізму в організмі виникає ланцюг біохімічних і фізіологічних змін (Edinger & Eisenman, 1970;Tolova, 1974;Fedoniuk et al, 2001;Burka et ak., 2006;Ippolitova, 2007;Zhuravin et al, 2007;Stevenson et al, 2015). Ці зміни необхідні для забезпечення оптимальних функцій життєво важливих органів в умовах гіпоксії.…”

“…При цьому перехід різноманітних речовин від матері до плода залежить від концентрації останніх у крові матері, рівня гемоциркуляції, проникності клітинних мембран. Важлива роль у даному процесі належить навколоплідній рідині, завдяки якій здійснюється постійний і швидкий обмін речовин між організмом матері та плода (Stevenson et al, 2015). Біохімічний склад навколоплідної рідини залежить від життєдіяльності та стану плода, характеризує процеси в його організмі зокрема, гемоцитопоез та забезпечення організму оксигеном, а в подальшому і в новонароджених телят (Balika et al, 1986;Korneev, 1991;Lebkova, 2000;Bellows et al, 2002;Shtemberg & Farber, 2007;Plesnova, 2007;Zamazii, 2008;Berry et al, 2014;Stevenson et al, 2015;Zamaziy et al, 2018).…”