Probability Of Insemination Research Articles

The effect of calcium supplementation on the economically important health parameters in a large dairy herd

The aim of our study was to investigate the association of per os calcium supplementation with the occurrence of animal health disorders in a large Hungarian dairy herd. The treatment of cows consisted of two per os calcium boluses on the day after calving. The probability of insemination, culling, mastitis, uterine disorders, and lameness were compared in the treated (n=168) vs. control cows (n=136) within 60 days in milk. Data were analysed by logistic regression. Cows that received calcium boluses were 8.09-times more likely to be inseminated (P<0.0001) and 0.34-times less likely to be culled (P=0.001) within 60 days in milk. Treated cows had reduced odds of developing mastitis (odds ratio, OR=0.50, P=0.0387) and lameness (OR=0.15, P=0.005) compared to their control herdmates. Per os calcium boluses can improve animal health in early lactation in high producing dairy cattle.

Economic evaluation of stall stocking density of lactating dairy cows

An increase in stall stocking density (SSD), as measured by the number of lactating cows per stall in a freestall barn, reduces cow performance, such as milk yield and fertility, but may increase farm profitability. Our objectives were to calculate effects of varying SSD on profit per stall for a range of effects on cow performances and external farm factors and store results in regression metamodels. The literature on quantified effects of SSD on cow performance that directly affects cash flow was found to be weak. We assumed effects of SSD on milk yield, probability of conception, and probability of culling. External farm factors were probability of insemination, feed price, and milk price. A herd budget-simulation model was used which mimics the performance of cows in a herd and calculates profit per stall per year and other results. The SSD varied from 100 (no overstocking) to 150% (severe overstocking) in steps of 10%. Sensitivity analyses for effects of SSD on cow performance and effects of external farm factors were performed. Three regression metamodels were developed. The first metamodel accurately predicted profitability at 100% SSD for all variations in the external farm factors. Optimal SSD varied from 100 to 150% SSD, depending on the combination of inputs, and was very sensitive to changes in the size of the milk loss and milk and feed prices. Average optimal SSD of all 2,187 combinations of inputs was 120% SSD and average maximum increase in profit was $99/stall per year. Of the 2,187 combinations of inputs, 18% were ascending (maximum increase in profit >150% SSD), 33% were descending (maximum profit at 100% SSD), and 50% had a maximum increase in profit between 100 and 150% SSD. The second metamodel accurately captured changes in profit for all combinations of biological and external inputs and SSD. A third metamodel captured breakeven daily milk losses which would result in the same profit as at 100% SSD given the same external farm factors. In conclusion, overstocking was profitable under plausible economic conditions in the United States. The 3 metamodels accurately captured the results for a wide range of values of the input variables. A tradeoff will occur between economically optimal SSD and animal welfare in some situations.

Extinction probabilities and times to extinction for populations of tsetse flies Glossina spp. (Diptera: Glossinidae) subjected to various control measures

A stochastic branching process was used to derive equations for the mean and variance of the probability of, and time to, extinction in tsetse populations. If the remnant population is a single inseminated female, the extinction probability increases linearly with adult mortality and is always certain if this mortality >3.5% per day even for zero pupal mortality. If the latter mortality is 4% per day, certain extinction is only avoided if adult mortality <1.5% per day. For remnant female populations >1, the extinction probability increases in a non-linear manner with adult mortality. Extinction is still certain for adult mortality >3.5% per day but, when the remnant population is >16, extinction is highly unlikely for adult mortality <2.5% per day if all females are inseminated. Extinction probability increases with increasing probability of sterile mating in much the same way as it does with increasing adult mortality. Extinction is assured if the probability of insemination can be reduced to 0.1. The required reduction decreases with increasing adult mortality. For adult mortality = 6-8% per day, the time to extinction increases only by one generation per order of magnitude increase in the starting population. Time to extinction is less sensitive to changes in the pupal than in the adult mortality. Reductions in the probability of insemination only become important when adult mortality is small; if the adult mortality is 8% per day, reducing the insemination probability from 1 to 0.1 only reduces the expected time to extinction by two generations. Conversely, increases in adult mortality produce important reductions in the required time even when the probability of insemination is 0.1. The practical, economic implication for the sterile insect technique is that the low-tech methods used to suppress tsetse populations should not be halted when the release of sterile males is initiated. The sterile insect technique should only be contemplated when it has been demonstrated that the low-tech methods have failed to effect eradication. The theory is shown to be in good accord with the observed results of tsetse control campaigns involving the use of odour-baited targets in Zimbabwe and the sterile insect technique on Unguja Island, Zanzibar.

Copulation duration and probability of insemination in Anthocoris whitei (Hemiptera: Anthocoridae) as a function of male body size

AbstractThe influence of male and female body size on copulation duration and probability of insemination was determined for Anthocoris whitei Reuter allowed to mate at two temperatures. Copulation duration decreased significantly with increasing male length or increasing relative size (male length divided by female length). Female length had no effect on copulation duration. We interrupted copulation at 20 or 40 min at both 25 and 15 °C to determine the interacting effects of male size, temperature, and copulation duration on probability of insemination. Insemination probabilities increased with increasing male size, increasing temperature, and increased duration of copulation. Large males were more successful than small males at inseminating females at cool temperatures and for severely shortened copulations. Results are consistent with the hypothesis that males of this species experience physical difficulties either in achieving intromission or in forcing sperm through the aedeagus, and that larger body size in males lessens these difficulties.

Female mate choice in a mating system dominated by male sexual coercion

In poeciliid fishes, males can gain copulation either by courting females or through sexual coercion. In some species these two tactics coexist. However, in about half of the poeciliids, males do not display, females never cooperate during copulation and all matings are achieved by thrusting the intromittent organ toward the genital pore of apparently unaware females. In one of these species, the eastern mosquitofish (Gambusia holbrooki), the probability of insemination is influenced by the time females are previously deprived of males, suggesting that females exert some control over the occurrence of mating even in a system apparently dominated by sexual coercion. In the present study we investigated the tendency of female mosquitofish to approach males in relation to their reproductive status and the time they were previously deprived of males. The tendency to approach males increased in females that were previously deprived of males and in females that had recently given birth. When allowed to choose between males, male-deprived females preferred larger males and normally pigmented over melanistic males. Females preferred groups of three males over a single male, whereas the preference for three males over a group of one male and two females was only marginally significant. Collectively, these results suggest that, even when coercive mating is the only tactic adopted by males, females may be able to influence the outcome of these attempts, and thus exert some control over the paternity of their offspring. Key words: sexual selection, female choice, sexual coercion, Gambusia holbrooki, fish, mating tactics. [Behav Ecol 12:59–64 (2001)]

Onion fly,Delia antiqua, oviposition and mating as influenced by insect age and dosage of male reproductive tract extract (Diptera: Anthomyiidae)

One hundred percent of virgin female onion flies,Delia antiqua, receiving ≥1/20 of a male equivalent of an aqueous extract of mature male reproductive tract remained unmated in the presence of males and began laying unfertilized eggs at a normally mated rate of about 20 eggs/female/day. The 50% behavioral response (BR50) fell between 1/40 and 1/20 of a male equivalent. Sex peptide responses are not always all-or-none. Some females receiving extract at ≤1/40 male equivalent oviposited at an intermediate rate. Moreover, at low sex peptide dosages, some females were fully activated ovipositionally but were receiptive to mating. A low level of sex peptide was present in 1-day-old males. Sex peptide titer rose with age until plateauing by 6 days posteclosion. Males began mating at 3 days, when they first had ample mature sperm; 50% of 6-day-old males mated. The mean number of females inseminated per male exposed to an excess of virgin females over 24 h was 4.3±0.6 (±SE). Presence of mature eggs was not always a prerequisite for mating, although probability of insemination was correlated with egg maturation. One-day-old preovipositional females receiving 1/20 of a male equivalent of extract began ovipositing when they had mature eggs at 5–6 days old. Therefore, sex peptide may act early and permanently or have a long half-life and affect behaviors once females reach sexual maturity. Male flies provide females with an excess of sex peptide in many cases.D. antiqua males transferred ca. 5–10 times more sex peptide than necessary to activate females fully. We suggest this excess is related to the speed of female response. It is yet unclear whether sex peptide potency or titer in Diptera has become exaggerated by intra- or intersexual selection.