Responsiveness to boar stimuli and change in vulvar reddening in relation to ovulation in weaned sows

Technological Tools and Artificial Intelligence in Estrus Detection of Sows-A Comprehensive Review

In animal farming, timely estrus detection and prediction of the best moment for insemination is crucial. Traditional sow estrus detection depends on the expertise of a farm attendant which can be inconsistent, time-consuming, and labor-intensive. Attempts and trials in developing and implementing technological tools to detect estrus have been explored by researchers. The objective of this review is to assess the automatic methods of estrus recognition in operation for sows and point out their strong and weak points to assist in developing new and improved detection systems. Real-time methods using body and vulvar temperature, posture recognition, and activity measurements show higher precision. Incorporating artificial intelligence with multiple estrus-related parameters is expected to enhance accuracy. Further development of new systems relies mostly upon the improved algorithm and accurate data provided. Future systems should be designed to minimize the misclassification rate, so better detection is achieved.

Using deep learning to accurately detect sow vulva size in a group pen with a single camera

This paper presents a non-contact method for the detection of changes in sow vulva size in a group pen. The traditional approach to estrus detection is manually pressing down on the back of the sow to elicit standing responses; however, this method causes undue distress for sows not in estrus. When a sow is in estrus, the vulva is red and swollen due to the presence of endocrine. Monitoring changes in vulva size to detect estrus with as little impact on the sow as possible is the focus of this study. This is achieved using a single camera combined with a deep learning framework. Our approach comprises two steps: vulva detection and vulva size conversion. Images of sows of Yorkshire, Landrace, and Duroc breeds were collected in group housing, and the vulva was detected through artificial markers and the network architecture of YOLO v4. Based on the internal and external parameters of the camera, the detected size was converted into millimeters and the results of manual measurement (MM) and automatic calculation combined to calculate the size of the vulva. Analysis of the calculated size compared with MM indicates that the object recognition rate of the system exceeds 97.06%, with a size error of only + 1.70 to -4.47 mm and high-calculation efficiency (>2.8 frames/s). Directions for future research include the automatic detection of pig width.

Artificial insemination in pigs today

Use of artificial insemination (AI) for breeding pigs has been instrumental for facilitating global improvements in fertility, genetics, labor, and herd health. The establishment of AI centers for management of boars and production of semen has allowed for selection of boars for fertility and sperm production using in vitro and in vivo measures. Today, boars can be managed for production of 20 to 40 traditional AI doses containing 2.5 to 3.0 billion motile sperm in 75 to 100 mL of extender or 40 to 60 doses with 1.5 to 2.0 billion sperm in similar or reduced volumes for use in cervical or intrauterine AI. Regardless of the sperm dose, in liquid form, extenders are designed to sustain sperm fertility for 3 to 7 days. On farm, AI is the predominant form for commercial sow breeding and relies on manual detection of estrus with sows receiving two cervical or two intrauterine inseminations of the traditional or low sperm doses on each day detected in standing estrus. New approaches for increasing rates of genetic improvement through use of AI are aimed at methods to continue to lower the number of sperm in an AI dose and reducing the number of inseminations through use of a single, fixed-time AI after ovulation induction. Both approaches allow greater selection pressure for economically important swine traits in the sires and help extend the genetic advantages through AI on to more production farms.

Impact of swine reproductive technologies on pig and global food production

Reproductive technologies have dramatically changed the way pigs are raised for pork production in developed and developing countries. This has involved such areas as pigs produced/sow, more consistent pig flow to market, pig growth rate and feed efficiency, carcass yield and quality, labor efficiency, and pig health. Some reproductive technologies are in widespread use for commercial pork operations [Riesenbeck, Reprod Domest Anim 46:1-3, 2011] while others are in limited use in specific segments of the industry [Knox, Reprod Domest Anim 46:4-6, 2011]. Significant changes in the efficiency of pork production have occurred as a direct result of the use of reproductive technologies that were intended to improve the transfer of genes important for food production [Gerrits et al., Theriogenology 63:283-299, 2005]. While some technologies focused on the efficiency of gene transfer, others addressed fertility and labor issues. Among livestock species, pig reproductive efficiency appears to have achieved exceptionally high rates of performance (PigCHAMP 2011) [Benchmark 2011, Ames, IA, 12-16]. From the maternal side, this includes pigs born per litter, farrowing rate, as well as litters per sow per year. On the male side, boar fertility, sperm production, and sows served per sire have improved as well [Knox et al., Theriogenology, 70:1202-1208, 2008]. These shifts in the efficiency of swine fertility have resulted in the modern pig as one of the most efficient livestock species for global food production. These reproductive changes have predominantly occurred in developed countries, but data suggests transfer and adoption of these in developing countries as well (FAO STAT 2009; FAS 2006) [World pig meat production: food and agriculture organization of the United Nations, 2009; FAS, 2006) Worldwide Pork Production, 2006]. Technological advancements in swine reproduction have had profound effects on industry structure, production, efficiency, quality, and profitability. In all cases, the adoption of these technologies has aided in the creation of a sustainable supply of safe and affordable pork for consumers around the world [den Hartog, Adv Pork Prod 15:17-24, 2004].

Timing of lactational oestrus in intermittent suckling regimes: consequences for sow fertility

Three intermittent suckling (IS) regimes were evaluated for their effects on lactational oestrus and subsequent fertility. Control sows were weaned (CW; n = 38) at d 26 ± 2 of lactation. In IS19-7D (n=40) and IS19-14D (n=42) sows, IS started at d 19 ± 1 of lactation and sows were weaned 7 or 14 d later. In IS26-7D (n=41), IS started at d 26 ± 1 of lactation and sows were weaned 7d later. During IS, sows were separated from their piglets for 10h/day. Oestrus detection was performed twice daily without a boar and ovulation was confirmed by ultrasound once a week. In IS19-7D, IS19-14D and IS26-7D, respectively, 50%, 64% and 61% of the sows showed oestrus and ovulation during IS (P>0.05), and, of the remaining sows, 100%, 93%, and 69% showed oestrus in the first week after weaning. In CW sows, 95% showed oestrus in the first week after weaning. Parity 1 sows were considerably less likely than older parities (23% vs. 68%) to show oestrus in lactation. Pregnancy rate of the first post partum oestrus (during lactation or after weaning) was 89% (CW), 92% (IS19-7D), 80% (IS19-14D) and 77% (IS26-7D) (P>0.05) and subsequent litter size was 14.5 ± 0.5, 14.5 ± 0.6, 15.3 ± 0.5 and 15.2 ± 0.8, respectively (P>0.05). Sows mated during lactation had similar pregnancy rate and litter size to those mated after weaning. Hence, ongoing lactation for the first 2-9 d of pregnancy did not negatively affect fertility. A total of 50-64% of IS sows showed lactational oestrus, regardless of the stage of lactation. Pregnancy rates and litter size were similar to control sows, and were not affected by stage of lactation at mating.

When is a cow in estrus? Clinical and practical aspects

Good detection of estrus is critically important in dairy husbandry. Incorrect detection of estrus is related to loss of profit due to extended calving intervals, milk loss, veterinary costs, etc. Detection of estrus remains a major problem despites enormous progress in the knowledge of reproductive physiology of the cow and in development of estrus detection aids. To achieve good estrus detection, many factors have to be taken into account. On one hand a cow has to express estrus and on the other hand the farmer has to detect it. Combined action of several hormones causes physiological changes that lead to ovulation and an environment in the uterus that allows sperm to fertilize the egg. Besides these internal actions, a number of external changes can be observed. When using visual observations, time of the day and time spend on observation have a great impact on detection rates. Many devices are available to aid in estrus detection, such as pedometers, mount devices, temperature, and hormone measurements. Expression of estrus can be influenced by many factors. Heritability, number of days postpartum, lactation number, milk production, and health are known to influence estrus expression. Environmental factors like nutrition, season, housing, herd size, etc. also play a role in estrus expression. To evaluate estrus detection, record keeping is very important; a number of formulas can be used to assess detection efficiency. Besides the farmer, the veterinarian and inseminator can play an important role in estrus confirmation and good insemination strategy. In the end, the time of ovulation and the age of the egg at sperm penetration is critical for conception. Therefore, emphasis in research needs to be on the timing of insemination relative to ovulation, and thus on the detection of ovulation.

The effect of fenceline bull exposure on expression of oestrus in dairy cows

The objective of this study was to investigate whether dairy cows visit and interact with a fenceline-housed bull more during oestrus than outside oestrus and whether fenceline bull contact affects expression of oestrus. At one end of a free stall a fence with vertical open bars was placed behind which a bull could be housed, allowing interactions with the cows. A closed fence with two blinded entrances was placed before the fence, creating a contact area. The experiment consisted of three treatments; it started with the control treatment (no bull on the farm) and was followed by bull treatment (a bull housed behind the fence) and no bull treatment (a bull present on the farm but not housed behind the fence). Signs of oestrus were observed every 4h for 30min and cows were equipped with pedometers. On the day of oestrus, cows were more frequent in the contact area during the bull treatment (12.0+/-9.8 times) and the no bull treatment (13.9+/-10.2 times) than during the control treatment (2.6+/-2.5 times). The frequency of visits to the contact area was low and not different between treatments on the other days (2.2+/-1.9 times). More cows had direct contact with the bull on the day of oestrus (71.4%) compared to the days outside oestrus (21.4-30%). The duration of direct contact with the bull was highly variable between cows and did not differ between oestrus and non-oestrus days. Behaviour and duration of oestrus were not affected by treatment but the relative increase in number of steps during oestrus tended to be higher in the bull (5.5+/-0.2) and no bull treatment (5.3+/-0.3) than in the control treatment (4.6+/-0.3). In conclusion, dairy cows in oestrus seem to be attracted by a bull or by the expectation of the presence of a bull, but fenceline bull exposure does not affect behavioural expression of oestrus.

Synchronization of ovulation in cyclic gilts with porcine luteinizing hormone (pLH) and its effects on reproductive function

The overall objective was to evaluate the use of porcine luteinizing hormone (pLH) for synchronization of ovulation in cyclic gilts and its effect on reproductive function. In an initial study, four littermate pairs of cyclic gilts were given altrenogest (15 mg/d for 14 d). Gilts received 500 microg cloprostenol (Day 15), 600 IU equine chorionic gonadotropin (eCG) (Day 16) and either 5mg pLH or saline (Control) 80 h after eCG. Blood samples were collected every 4h, from 8h before pLH/saline treatment to the end of estrus. Following estrus detection, transcutaneous real-time ultrasonography and AI, all gilts were slaughtered 6d after the estimated time of ovulation. Peak plasma pLH concentrations (during the LH surge), as well as the amplitude of the LH surge, were greater in pLH-treated gilts than in the control (P=0.01). However, there were no significant differences between treatments in the timing and duration of estrus, or the timing of ovulation within the estrous period. In a second study, 45 cyclic gilts received altrenogest for 14-18d, 600 IU eCG (24h after last altrenogest), and 5mg pLH, 750 IU human chorionic gonadotropin (hCG), or saline, 80 h after eCG. For gilts given pLH or hCG, the diameter of the largest follicle before the onset of ovulation (mean+/-S.E.M.; 8.1+/-0.2 and 8.1+/-0.2mm, respectively) was smaller than in control gilts (8.6+/-0.2mm, P=0.05). The pLH and hCG groups ovulated sooner after treatment compared to the saline-treated group (43.2+/-2.5, 47.6+/-2.5 and 59.5+/-2.5h, respectively; P<0.01), with the most synchronous ovulation (P<0.01) in pLH-treated gilts. Embryo quality (total cell counts and embryo diameter) was not significantly different among groups. In conclusion, pLH reliably synchronized ovulation in cyclic gilts without significantly affecting embryo quality.

Sexual behavior of male pigs

Two major characteristics of males that affect the likelihood of achieving copulation are the sexual motivation and mating competency of the male. The behavior of domestic animals, including their sexual behavior, is dependent upon a complex interaction between the organism's internal and external environment. In male pigs, as in other mammalian species, it is clear that testicular steroids are required to maintain sexual behavior and testosterone plays a critical role. Consistent with studies in other species, it is apparent in male pigs that there is a threshold circulating concentration of androgens and/or estrogens required to maintain sexual behavior and that the level of sexual motivation is unrelated to levels of sex steroids providing these are adequate for normal sexual behavior. Key aspects of the external environment that affect the sexual behavior of the male pig include genetic, seasonal, social, sexual and psychological factors.

Effects of boar contact and housing conditions on estrus expression in sows

In this paper, the authors review the effects of boar contact and different components of boar presence on onset and expression of estrus in weaned sows. Evidence is presented that boar contact may influence LH release, onset of follicle development and timing of ovulation after weaning. Once the sow is in estrus it is important that she shows estrous behavior, because her expression of estrus determines whether she will be inseminated. Boar contact or components thereof affect expression of estrus in sows. There are distinct differences between different components of boar contact in their effectiveness in the induction of estrous behavior (standing response) in sows. Habituation to boars (due to frequency of boar contact or housing of boars near sows) also affects estrus expression in sows. It is important to inseminate sows at the correct moment relative to ovulation. The use of different estrus detection protocols (e.g., by giving sows different levels of boar stimuli during estrus detection) may result in the definition of distinct periods of estrus that may help to predict the moment of ovulation. However, results to date are not very encouraging. Besides boar stimuli, the housing conditions of sows may affect onset of estrus and estrus expression. This paper focuses on social sow-to-sow interactions. The effects of group housing (as compared to individual housing) on onset of estrus and expression of estrus are equivocal. These effects likely depend on factors like aggression between pen mates, reproductive status of pen mates and social rank of sows within the group.