Functional Teats Research Articles

Can body nosing in artificially reared piglets be reduced by sucking and massaging dummies?

Selection for hyper-prolific sows has substantially increased litter size. Consequently, the number of piglets in a litter may exceed the number of functional teats. To solve this problem, surplus piglets may be removed from the sow 2 days after birth and raised artificially. However, these piglets show increased levels of oral behaviours, such as belly nosing, directed at other piglets. This behaviour resembles massaging and sucking at the sow’s udder and thus is considered to be redirected suckling behaviour. The present study investigated whether oral behaviour directed at piglets can be reduced in artificially reared piglets by providing them with sucking and massaging dummies. In a two-by-two between-group factorial design, the artificial rearing pens were equipped with one of four treatments: a sucking dummy, a massaging dummy, a combined sucking–massaging dummy, or no dummy. The behaviour of 126 piglets (in 21 groups of 6 piglets) was scored from video by continuous focal observation lasting 90 min per piglet each on days 4 and 18 after introduction to the artificial rearing system. Data were analysed using linear mixed-effects models. Body nosing (composed of belly nosing and nosing on any other body part) increased from day 4 to 18 in all treatments, but piglets provided with a combined sucking–massaging dummy showed the smallest increase. Piglets spent more time nosing the combined dummy than the sucking or the massaging dummy. However, there was no causal inverse relationship between the duration of body nosing and dummy nosing. All but one piglet showed body nosing at least once. Resting, play-fighting, or oral manipulation of piglets (other than body nosing), dummies, and pen equipment were hardly affected by the treatments. Piglets with a combined dummy tended to have a longer average resting bout duration compared with piglets in other treatments. In conclusion, only the combined sucking–massaging dummy was effective in reducing the increase in body nosing over time. However, this reduction was rather small in absolute terms and the combined dummy did not prevent body nosing. The tested dummies were thus not successful in eliminating the redirected oral behaviour in artificially reared piglets.

Trade-offs between litter size and offspring fitness in domestic pigs subjected to different genetic selection pressures

Artificial selection of the domestic pig (Sus scrofa domesticus) offers a useful model for investigating changes in behaviour associated with reproductive trade-offs between litter size and fitness of offspring. The aim of this study was to evaluate effects of litter size on teat stimulation, sibling competition, and pre-weaning survival and growth in three populations of domestic pigs subjected to different selection pressures (a maternal line selected for high reproductive investment, a paternal line selected for meat production traits, and a crossbred line). We predicted that, with increasing litter size, piglets would spend more time in udder massage, be less likely to gain access to a teat during milk letdown and, if surviving to weaning, have lower, more variable body weights. We also predicted that maternal line sows would wean more piglets of higher weight, despite larger litter sizes, than paternal line sows. Sows (maternal line, n=12, paternal line, n=12, crossbred line, n=14) were loose-housed with their litters in individual farrowing pens. We collected data on piglet behaviour during nursings at 1day of age, when sibling competition was expected to be most intense. Piglets were weaned at 35days of age, when they were weighed and cumulative mortality was calculated. As predicted, piglets in larger litters spent more time in pre- and post-letdown udder massage (P=0.050 and P<0.001, respectively). In larger litters, more piglets survived to weaning (P=0.002), but at a cost of a lower proportion of nursings with letdown (P<0.001), longer nursing intervals on average (P=0.018), more piglets without a functional teat at letdown (P<0.001), an increased risk of mortality due to starvation (P<0.001) and crushing (P=0.002), and lower (P=0.039), more variable (P=0.002) body weights at weaning. In the maternal line, nursing intervals lengthened with increasing litter size (litter size×breed: P<0.001) despite more post-letdown udder massage (P<0.001), and mortality due to crushing rose with increasing litter size (P<0.001), without differential increments in number, weight or weight uniformity of weaned piglets with increasing litter size between breeds (litter size×breed: P>0.1). Our results suggest that further artificial selection for larger litters in maternal lines will be unsustainable because increments in the number of piglets weaned have increasing costs (e.g. sibling competition, mortality, uneven growth) that compromise piglet welfare and fitness.

The effect of double nursing, an alternative nursing strategy for the hyper-prolific sow herd, on herd performance

BackgroundHyper-prolific sows produce more piglets than they can suckle, as the number of milk producing teats of the sow is lower (twelve to sixteen) than the number of live born piglets per litter. Farmers and farm workers are struggling to feed this surplus of piglets. To minimize suckling piglet mortality, litter size at 24 hours after parturition should not exceed the number of functional teats of the sow. Strategies to adequately nurse or feed the surplus of piglets after 24 hours are limited and mostly restricted to either fostering piglets by other sows, supplying milk replacers (formula) or early weaning and rearing on formula.Case presentationIn this case report we describe the design and application of a so called ‘double nursing’ strategy, for which one sow simultaneously nurses two litters from birth to weaning. Piglet mortality and reproductive parameters of sows that have nursed two litters are compared, over a three year period, with those that nursed one litter.ConclusionIn this herd, the double nursing strategy appeared to be a successful strategy. Double nursing sows experienced a lower piglet mortality, despite the double nursing strategy. The negative effects on reproduction proved to be limited, there was a negative effect on litter size in subsequent litters, but no significant effect on the interval weaning to next conception. It has to be noted though that not all characteristics on which double nursing selection takes place, could be taken into account during statistical analyses.

Does duration of teat use in first parity affect milk yield and mammary gene expression in second parity?

It was recently shown that a teat that is not used in the first lactation will have a reduced development and milk yield in the second lactation. In the current study, the impact of imposing a suckling period of 2, 7, or 21 d during the first lactation on piglet performance, milk composition, endocrine status, and mammary gene expression of sows in their second lactation was studied. Pregnant Yorkshire gilts were divided into 3 groups according to lactation length: 1) 2-d lactation (2D; = 20), 2) 7-d lactation (7D; = 20), and 3) 21-d lactation (21D; = 21). After weaning, sows were bred and kept for a second parity. In both lactations, litters were standardized to 12 piglets with 12 functional teats and surplus teats were sealed. In the second lactation, piglets were weighed on d 2, 7, 14, 21 (weaning), 31, and 56 postpartum, and sow feed intake was recorded. On d 110 of gestation and on d 21 of lactation, mammary biopsies were performed on 10 sows per treatment to obtain parenchymal tissue samples for determination of mRNA abundance for , , , , , and genes. Milk samples and jugular blood samples were also obtained from sows on d 21 of lactation. Standard composition analyses (DM, fat, protein, and lactose) were done in milk. Concentrations of prolactin, IGF-1, glucose, and urea were measured in blood. There was a tendency for 21D sows to consume more feed than 2D or 7D sows during the first week of lactation ( < 0.10). There was no treatment effect on BW of piglets at any time until d 56 ( > 0.10). Concentrations of prolactin, IGF-1, urea, and glucose in sows on d 21 of lactation were not affected by treatment ( > 0.10). Dry matter, fat, protein, and lactose contents in milk were not altered by treatment ( > 0.10). On d 110 of gestation, gene expression was greater ( = 0.05) in 21D sows than in 7D sows. On d 21 of lactation, gene expression of was greater ( = 0.05) and that of tended to be lower ( < 0.10) in 7D sows than in 2D sows. The mRNA abundance of also tended to be lower ( < 0.10) in 2D sows than in 7D sows. Results indicate that increasing the duration of lactation from 2 d to 7 d or to 21 d in first-parity sows did not improve growth rate of their piglets in the subsequent lactation. This suggests that suckling of a teat for 2 d during the first lactation is sufficient to ensure optimal mammary development.

Genetic analysis of teat number in pigs reveals some developmental pathways independent of vertebra number and several loci which only affect a specific side

BackgroundNumber of functional teats is an important trait in commercial swine production. As litter size increases, the number of teats must also increase to supply nutrition to all piglets. Therefore, a genome-wide association analysis was conducted to identify genomic regions that affect this trait in a commercial swine population. Genotypic data from the Illumina Porcine SNP60v1 BeadChip were available for 2951 animals with total teat number (TTN) records. A subset of these animals (n = 1828) had number of teats on each side recorded. From this information, the following traits were derived: number of teats on the left (LTN) and right side (RTN), maximum number of teats on a side (MAX), difference between LTN and RTN (L − R) and absolute value of L − R (DIF). Bayes C option of GENSEL (version 4.61) and 1-Mb windows were implemented. Identified regions that explained more than 1.5% of the genomic variation were tested in a larger group of animals (n = 5453) to estimate additive genetic effects.ResultsMarker heritabilities were highest for TTN (0.233), intermediate for individual side counts (0.088 to 0.115) and virtually nil for difference traits (0.002 for L − R and 0.006 for DIF). Each copy of the VRTN mutant allele increased teat count by 0.35 (TTN), 0.16 (LTN and RTN) and 0.19 (MAX). 15, 18, 13 and 18 one-Mb windows were detected that explained more than 1.0% of the genomic variation for TTN, LTN, RTN, and MAX, respectively. These regions cumulatively accounted for over 50% of the genomic variation of LTN, RTN and MAX, but only 30% of that of TTN. Sus scrofa chromosome SSC10:52 Mb was associated with all four count traits, while SSC10:60 and SSC14:54 Mb were associated with three count traits. Thirty-three SNPs accounted for nearly 39% of the additive genetic variation in the validation dataset. No effect of piglet sex or percentage of males in litter was detected, but birth weight was positively correlated with TTN.ConclusionsTeat number is a heritable trait and use of genetic markers would expedite selection progress. Exploiting genetic variation associated with teat counts on each side would enhance selection focused on total teat counts. These results confirm QTL on SSC4, seven and ten and identify a novel QTL on SSC14.

Identification of novel candidate genes for the inverted teat defect in sows using a genome-wide marker panel

The number of functional teats is an important selection criterion in pig breeding. Inherited defects of the udder, such as the inverted teat, do have a considerable negative impact on the nursing ability of the sow. To investigate the genetic background of this defect and the number of functional teats in Swedish maternal lines, samples from 230 Yorkshire pigs were selected for genotyping using the PorcineSNP60K BeadChip (Illumina Inc.), each pig with at least one inverted teat was matched with one non-affected pig (fullsib or pairs with matching herd and gender). A genome-wide association study on these 230 pigs was performed using the two-step approach implemented in GenABEL using 46,652 single nucleotide polymorphisms across all autosomes and the X chromosome. A number of significant regions were identified for the inverted teat defect on chromosomes 2, 10, and 18. Many of the regions associated with the number of functional teats were located in the same or close regions, except two associated markers on the X chromosome and one on chromosome 3. We identified some of the regions on chromosomes previously reported in one linkage and one gene expression study. We conclude, despite being able to suggest new candidate genes, that further studies are needed to better understand the biologic background of the teat development. Despite the in-depth comparison of identified regions for the inverted teat defect done here, more studies are required to allow a clear identification of genetic regions relevant for this defect across many pig populations.

Top-dressing 1% arginine supplementation in the lactation diet of sows does not affect the litter performance and milk composition

ABSTRACT: The study aimed to evaluate the effects of arginine supplementation in the lactation diet of sows on their milk composition, litter performance and piglet survival. Sixty-four lactating Landrace x Large White sows, parity 1 to 7, were randomly assigned to two treatments: 1) Control - a corn/soybean meal based diet with 1.10% standardized ileal digestible (SID) lysine and 3,475kcal of metabolizable energy (ME) kg-1, and 2) arginine - the control diet top-dressed daily with arginine at 1% of feed allowance. The daily feed allowance per sow was 5.0 and 7.5kg from day (D)0 to D7 and D8 to D21, respectively. The average litter size was 12.8 piglets after cross-fostering. Litters were weighed on D1, D10, and D21 of lactation and pre-weaning mortality was recorded. Samples of milk (60mL) were collected from all functional teats at D10 and D20 of lactation. There were no effects (P&gt;0.05) of arginine supplementation on piglet weight, litter weight, and average daily gain of piglets at D10 and D21 of lactation. The interaction between weight day and treatment was not significant (P&gt;0.05) for any of these response variables. The percentages of piglets that survived until D10 and D21 were 90.3% and 88.3%, respectively, with no difference (P&gt;0.05) between treatments. There were no effects (P&gt;0.05) of the lactation day (D10 or D20), treatment or the interaction between them on crude protein and amino acid content in milk. Top-dressing arginine at 1% of feed allowance of the lactation diet of sows does not affect litter performance and survival and does not influence the amino acid content or arginine: lysine ratio of milk.

Udder characteristics of importance for teat use in purebred and crossbred pigs.

Possible side effects of the current sow selection criteria on udder characteristics and their influence on teat use and functionality have not yet been investigated. The first aim of the present study was to investigate differences in udder morphology characteristics (distance between teats in a pair, teat length, and teat diameter) in 2 different pure breeds (Norsvin Duroc [ND; = 12] and Norsvin Landrace [NL; = 12]) and 1 crossbreed (Norsvin Landrace × Yorkshire [NL×Y; = 14]) at 3 different time periods (Days 1, 21, and 35) during lactation. Second, we also investigated the association between udder morphology and teat use on d 1 and if some of these characteristics influence whether teats become nonfunctional (from d 1 to 35) during lactation. During lactation, udder morphology (teat pair distance, teat length, and diameter of functional teats) and teat use (from 6 consecutive nursings: functional teats being used/not being used and which teat row [left or right] was uppermost) were documented. The NL had shorter distance between teat pairs than ND ( = 0.030). Teat pair distance increased with sows' parity ( = 0.010) and was affected by teat position ( < 0.001). The ND had shorter teats than NL and NL×Y ( < 0.001). Teat length and diameter increased with parity ( = 0.027 and = 0.043, respectively) and were affected by teat position ( < 0.001 and < 0.001, respectively). Functional teats were less used on d 1 postpartum (21.4%) than at 2 later time periods (10.4% on Day 21 and 4.7% on Day 35; < 0.001) during lactation. On d 1, the greater the distance between teat pairs in the middle and posterior position, the higher was the proportion of not-used functional teats ( = 0.003), with a larger decline in the lower teat row ( < 0.001), where approximately half of middle and posterior teats were not used. Proportion of not-used functional teats in the lower middle position increased when the teat pair distance exceeded 16 cm, whereas in the lower posterior position, this limit was 14 cm. Furthermore, the proportion of not-used teats on d 1 influenced teats becoming nonfunctional during lactation ( < 0.001). The greater the distance between pairs, the more teats became nonfunctional irrespective of teat position ( < 0.001). The present results suggest that teat pair distance is of importance for teat use in all breeds and should be included in the breeding program to ensure colostrum intake and maintain teat functionality during lactation.

Neonatal piglets are able to differentiate more productive from less productive teats

A previously-validated method to induce variation in milk production between teats of the same udder that is not related to the ante-posterior location of the teat was used. In the first lactation, over half of the sows’ teats (teats 1, 2, 5, 6, and 7 from 1 side of the udder, and teats 3, 4, and 7 from the other side) were sealed with tape so that they were non-functional (treated (TRT) teats), whilst the other six unblocked teats were left unblocked so that they were functional (control (CTL) teats). Sixty-four piglets in eight litters were observed on days 2 and 10 of the second lactation when all teats were available. Teat use, piglets’ behaviour during nursings and growth performances were analysed according to a 2×3 factorial design including the position (anterior, middle and posterior) and the treatment (CTL vs. TRT) of teats as fixed factors. Analysis of the location of piglets along the udder at milk ejection revealed that teat use on day 2 was affected by position and treatment of teats, but teat use on day 10 was only affected by position. Moreover, on day 2, the total number of fights was greater for CTL than TRT teats (9.6 vs. 6.2 fights/day, respectively; P<0.001) and the percentage of time the teat was suckled during post-massage was longer for CTL than TRT teats (54.9 vs. 44.7%, respectively; P=0.022). Piglets that suckled preferentially from CTL teats in early lactation had an increased growth rate until the end of the post-weaning period (BW at day 56: CTL=23.66 vs. TRT=21.32kg; P=0.004). Current results confirmed that teats used in first lactation produce more milk in second lactation, and that piglets are able to detect this difference. When considering the whole litter, piglets had a preference for previously-used teats and competed to get access to them. We conclude that choice and competition of piglets for higher-producing teats happens in the early stage of lactation, during the establishment of the teat order and that suckling preferentially from such teats has long-term positive effects on piglets’ growth.

Comparison of the behaviour of piglets raised in an artificial rearing system or reared by the sow

Over the last 15 years, rising sow fertility has led to a considerable increase in litter size. As a consequence, the number of live born piglets may outnumber the number of functional teats, and surplus piglets are removed from the sow at the age of 3–6 days and fed with artificial milk. The objective of this study was to compare the behaviour of piglets raised in a commercially available artificial rearing system (group size: seven piglets) with that of piglets reared by the sow in a loose farrowing pen (seven focal piglets observed per litter). The behaviour of 98 piglets raised artificially (7 batches) and 82 piglets reared by the sow (6 batches) was videotaped on days 4, 11 (artificially raised piglets only) and 18 after introduction of the piglets to the artificial rearing system. Belly nosing, manipulation of a pen mate, play-fighting, aggressive behaviour and resting were assessed by continuous focal observation twice a day in the periods from 05:00 to 10:15 and from 13:00 to 18:15. Data were analysed by using linear mixed-effects models.Belly nosing was hardly ever observed in piglets reared by the sow, whereas the duration as well as the frequency of this behaviour increased between days 4 and 18 in piglets raised artificially. Moreover, artificially raised piglets spent more time manipulating a pen mate, showed less play-fighting, exhibited more aggressive behaviour and had shorter resting bouts compared with piglets reared by the sow. Finally, total duration of resting decreased from day 4 to day 18 in artificially raised piglets and increased in piglets reared by the sow.It is concluded that piglets removed from the sow at an early age and raised artificially redirect massaging behaviour to their pen mates, resulting in high levels of belly nosing and indicating impaired animal welfare. Moreover, the small space allowance in the tested artificial rearing system may additionally account for behavioural differences observed between artificially raised piglets and piglets reared by the sow in a loose farrowing pen.

Inverted teats (Mammillae invertitae) in gilts – Effect on piglet survival and growth rate

In the modern pig industry, the increasing number of piglets born per litter augments the importance of the number of functional teats in the sow. The aim of this study was to evaluate the function and importance of inverted teats during nursing and to analyze structural and functional differences between the mammary glands of inverted teats versus normal teats. Nine farrowing gilts (8 purebred Swedish Yorkshire gilts and 1 cross between Swedish Yorkshire and Norwegian Landrace) and 94 piglets (59 piglets suckling normal teats, 32 piglets suckling protruded teats [i.e., previously inverted], 2 piglets suckling inverted teats, and 3 piglets suckling considerably smaller teats) were included in the study. Teat fidelity (keeping the same teat between the nursings) was registered, excluding the first 48 h postpartum. Piglet weight was recorded daily during the first week of life and thereafter once a week until weaning at 4 wk of age. Weight and growth rate were analyzed using repeated observation mixed-model analysis of variance. The 2 piglets that suckled the inverted teats were not able to emerge the teats and they were euthanized 4 and 8 d after birth, respectively, due to loss of BW. The average weight at weaning (28 d of age) was 8.1 kg (range 3.2-13.8 kg). In the normal teats (n = 53), the weight of the corresponding mammary gland tissue at necropsy was positively correlated to the piglet average daily weight gain during wk 2 (r = 0.33, P < 0.05), 3 (r = 0.55, P < 0.001), and 4 (r = 0.47, P < 0.001). In the protruded teats (n = 32), the weight of the corresponding mammary gland tissue was positively correlated to the piglet average daily weight gain during wk 2 (r = 0.63, P < 0.001) and 3 (r = 0.43, P < 0.05). Among the piglets nursing normal teats, 82% kept fidelity to its teat and the corresponding percent for the protruded teats was 26%. In 7 of the 9 sows, the weaning weight of the piglets suckling protruded teats was numerically lower compared to the piglets suckling normal teats, although the difference was not statistically significant. Piglets nursing small teats had lower weaning weight (4.8 kg) and the corresponding mammary tissue also had lower weight (335 g). This study indicates the importance of an adequate number of well-developed and well-functioning teats in healthy sows for the growth and development of the piglets but also emphasizes the complexity of the interaction between the nursing sow and her piglets.

Genetic analysis of teat number and litter traits in pigs

The aim of this study was to analyse, on data on purebred Yorkshire pigs in Swedish nucleus herds, the genetic correlation between teat number (both functional and non-functional) recorded at performance testing (at approx. 100 kg live weight), litter size at birth and litter weight at 3 weeks of age. Animal mixed-model analysis was applied on the data available (57,000 performance tested pigs, 10,000 1st-parity litters and 6500 2nd-parity litters). The estimated heritability for number of functional teats was 0.31, for number of non-functional teats 0.09 and for total number of teats 0.39. Number of non-functional teats was negatively genetically correlated with number of functional teats (rG = -0.34), and positively correlated with litter size (parity 1; +0.20) and number of stillborn piglets (parity 2; +0.34).

The welfare implications of large litter size in the domestic pig II: management factors

AbstractIncreasing litter size has long been a goal of pig(Sus scrofa domesticus)breeders and producers in many countries. Whilst this has economic and environmental benefits for the pig industry, there are also implications for pig welfare. Certain management interventions are used when litter size routinely exceeds the ability of individual sows to successfully rear all the piglets (ie viable piglets outnumber functional teats). Such interventions include: tooth reduction; split suckling; cross-fostering; use of nurse sow systems and early weaning, including split weaning; and use of artificial rearing systems. These practices raise welfare questions for both the piglets and sow and are described and discussed in this review. In addition, possible management approaches which might mitigate health and welfare issues associated with large litters are identified. These include early intervention to provide increased care for vulnerable neonates and improvements to farrowing accommodation to mitigate negative effects, particularly for nurse sows. An important concept is that management at all stages of the reproductive cycle, not simply in the farrowing accommodation, can impact on piglet outcomes. For example, poor stockhandling at earlier stages of the reproductive cycle can create fearful animals with increased likelihood of showing poor maternal behaviour. Benefits of good sow and litter management, including positive human-animal relationships, are discussed. Such practices apply to all production situations, not just those involving large litters. However, given that interventions for large litters involve increased handling of piglets and increased interaction with sows, there are likely to be even greater benefits for management of hyper-prolific herds.

Genetic analysis of functional and non-functional teats in a population of Yorkshire pigs

.Litter size is included in the goal of most pig breeding programmes. With an increased litter size, the number of functional teats, which are needed to achieve piglet weight gain and uniform litters, becomes increasingly important. The non-functional (e.g. inverted, blind, or small) teats might have a lower value for the nursing of the piglets. In Sweden, within the pig breeding company Nordic Genetics, the total number of teats, as well as the numbers of functional and non-functional teats, are recorded for purebred Yorkshire pigs both at 3 weeks of age (identity marking) and at about 5 months of age (performance testing). In 2010, 13% of the Swedish purebred Yorkshire pigs had at least one non-functional teat at performance testing (100kg live weight). The aim of this study was to analyse both genetic and phenotypic variation among the teat traits and to analyse the associations among the teat traits, age and sidefat thickness at 100kg live weight. In the phenotypic analyses there were significant differences between males and females for all analysed teat traits. Males showed a higher number of functional teats and females three times more non-functional teats at 100kg live weight. In the genetic analyses the records for males and females were treated as representing different traits. The estimated heritability of total number of teats and the number of functional teats, both at 3 weeks of age and at 100kg live weight, was in the range 0.36–0.42. The heritability of the number of non-functional teats at 3 weeks of age was low, 0.02, for both males and females. Surprisingly, at 100kg live weight, the heritability of non-functional teats was moderate, 0.29, for females, but still low, 0.03, for males. Further studies are required to investigate whether there is a biological explanation for this finding, or if there is a difference between the genders in the recording procedure of this trait. The only significant genetic correlation found between the teat traits and performance traits was for male pigs; the genetic correlation for the relationship between the number of non-functional teats at 3 weeks of age and the age at 100kg was −0.2. Thus, slowly growing pigs have a lower number of non-functional teats. Our results show that the teat number efficiently can be improved by selection. However non-functional teats is a complex trait and further studies need to be performed to investigate the possibilities to improve selection against the non-functional teats.

La variabilité des performances animales en élevage porcin : description et implications pratiques

La variabilité de la prolificité est maîtrisable par l'éleveur tant que le nombre de porcelets nés vivants n'excède pas le nombre de tétines fonctionnelles dans la maternité : des adoptions entre portées permettent alors d'ajuster le nombre de porcelets allaités aux capacités laitières des truies. Quand la prolificité est très élevée, la gestion des porcelets devient plus compliquée et la variabilité de leurs poids de naissance pénalise les chances de survie des individus les plus petits. S’ensuit aussi une variabilité accrue des performances de croissance. Des solutions à court terme peuvent être mises en oeuvre, en particulier l'adaptation selon le poids des animaux des soins pratiqués aux porcelets à la naissance, la constitution de lots de porcs sur la base du poids au sevrage et à l'entrée en engraissement, et l'adaptation des transitions alimentaires en fonction du poids moyen de chaque lot. Malgré ces pratiques, la variabilité des poids au sein d'une bande persiste jusqu’en fin d'engraissement, compliquant l'organisation des départs pour l'abattoir. Ceux-ci sont généralement gérés au mieux de l'intérêt économique de l'éleveur en relation avec la grille de paiement basée en partie sur le poids de carcasse. Sans attendre les progrès de la sélection génétique pour limiter la variabilité des performances des truies et des porcelets, la prise en compte précoce des besoins individuels des truies au sein d'une bande permettrait de gérer l'évolution de l'adiposité maternelle pendant la gestation et faciliter le déroulement des mises bas. La prise en compte de l'évolution des besoins nutritionnels au cours de la gestation par des plans d'alimentation adaptés améliore la vitalité des nouveau-nés, mais jusque-là ne joue pas sur la variabilité des poids intra-portée. Ces améliorations sont obtenues le plus souvent dans des troupeaux expérimentaux, et restent à généraliser dans les élevages de production.

A note on teat accessibility and sow parity — consequences for newborn piglets

The aim of the present study was firstly to investigate the accessibility of the two teat rows in sows of different parities and litter sizes during the first 24h after birth, and secondly, how teat accessibility affects latency to suckle, piglet temperature development and weight gain shortly after birth. Nine loose housed sows and their piglets were observed at the time of farrowing to document the following: which teat row and which teat individual piglets first suckled, and the latency from birth to first suckle, in addition to individual piglet weight and rectal temperature at birth, 2h and 24h of age. On average, 46.5% of the functional teats were suckled in sows with parity 1 or 2, and this was further reduced to 41% in older sows. Fewer piglets were suckling the lower teat row (during the first 24h) as parity increased (P<0.001). Piglets from high parity sows had a longer latency from birth to first suckle (P<0.05), and a lower weight gain from birth to 24h compared to piglets from low parity sows (P<0.05). More piglets were suckling the lower teat row as litter size increased (P<0.01), and there was a lower weight gain from birth to 24h in piglets suckling the lower teat row (P<0.1). In conclusion, less than half of the sows' functional teats were suckled, and the majority of piglets suckled the upper teat row. These biases increased in the older sows, resulting in longer latencies to suckle and reduced weight gain in these piglets.

Management routines at the time of farrowing—effects on teat success and postnatal piglet mortality from loose housed sows

The aim of this experiment was to study the effects of six different management routines at the time of farrowing on latency to first suckle, heat loss, weight gain and postnatal mortality. A total of 872 piglets from 67 loose housed sows in a commercial pig unit were subjected to one of six different management routines: control (CON n = 14), no treatment; (CREEP n = 13), placed in creep area; (UDDER n = 10), placed at the udder; (DRY n = 10), dried and placed back where found; (DRYCREEP n = 9), dried and placed in creep area; and (DRYUDD n = 11), dried and placed at the udder. The latency from birth to first suckle, rectal temperature at birth, 2 hours and 24 hours were measured for each piglet, in addition to weight at birth, 2 hours and 24 hours. Latency from birth to first suckle was shortest for piglets in the DRYUDD treatment, followed by the UDDER treatment ( P < 0.001). More live born piglets died in the UDDER treatment compared to the other treatments ( P < 0.001), but there were no other differences between the treatments with regards to postnatal mortality. There was a significant interaction between treatment and batch, with a significantly lower postnatal mortality in the DRYUDD treatment than CON in batch 2, but not in batch 1 and 3 ( P < 0.001). Large litter sizes resulted in a higher postnatal mortality in all treatments ( P < 0.001), and tended to reduce latency to suckle ( P < 0.1). In conclusion, drying the piglets after birth and placing them at the udder resulted in reduced postnatal mortality in batch 2, but not in the other two batches. Despite having the largest mean litter size of the treatments, less than 10% of the piglets in DRYUDD died, which is remarkably low for loose housed sows. Regardless of treatment, several piglet-related factors were found to be highly important for postnatal mortality, such as the number of functional teats per piglet ( P < 0.001), birth weight ( P < 0.001), the latency from birth to first suckle ( P < 0.01), and rectal temperature at 2 hours after birth ( P < 0.001).

Association of parathyroid hormone‐like hormone (PTHLH) and its receptor (PTHR1) with the number of functional and inverted teats in pigs

Parathyroid hormone-like hormone gene (PTHLH) and its receptor, parathyroid hormone/ parathyroid hormone-like hormone receptor 1 (PTHR1), play a role in epithelial mesenchymal interactions during growth and differentiation of different tissues and anatomic structures, including teats. Therefore, PTHLH and PTHR1 were evaluated as functional candidate genes for their effects on number and shape of teats in pigs. In particular, focus was on the occurrence and number of inverted teats, the most frequent and economically relevant teat developmental defect in pigs. For this purpose, association and linkage of the PTHLH gene and the PTHR1 gene with inverted teat defect and the total number of teats and inverted teats were studied in an experimental Duroc and Berlin Miniature pig (DUMI) population. Polymorphism C1819T of PTHR1 was significantly associated with inverted teat phenotype (p = 0.014), total number of teats (p = 0.047) and was close to significance with the number of inverted teats (p = 0.078). Polymorphism C375T of PTHLH was close to significance with the inverted teat phenotype (p = 0.122) and showed no significant association with the total number of teats (p = 0.621) and the number of inverted teats (p = 0.256) in the DUMI population. Association analyses were also performed for combined effects of PTHLH and PTHR1 in order to address potential interaction, however, revealed no indication of effects of interaction. The function, position and the association shown here promote PTHR1 as a candidate gene for number of teats and in particular for affection by and number of inverted teats.

Evidence for association of lymphoid enhancer-binding factor-1 (LEF1) with the number of functional and inverted teats in pigs

The lymphoid enhancer-binding factor-1 (LEF1) belongs to a family of regulatory proteins that share homology with the high mobility group protein-1 (HMG1). The LEF1 gene is a mediator in the canonical Wnt-signalling pathway required for morphogenesis of early mammary gland during embryogenesis. Here we describe the molecular characterisation of the porcine LEF1 gene and its association with number of teats and inverted teats in experimental and commercial populations. The 2357-bp cDNA sequence contains an 1197-bp open reading frame encoding a protein of 398 amino acids. The porcine LEF1 protein shares high identity with LEF1 in other mammalian species. The LEF1 gene contains 12 exons and maps to pig chromosome 8 (SSC8). We identified two single nucleotide polymorphisms (SNPs), a T1351C transition and an A1666C transversion, in the 3′ end of LEF1. Associations of the SNP A1666C with presence of inverted teats (P≤ 0.01), total number of teats (P ≤ 0.01) and total number of inverted teats (P ≤ 0.01) were highly significant; SNP T1351C showed near significance with total number of inverted teats (P ≤ 0.1) in the experimental DUMI population. SNP T1351C was significantly associated with total number of inverted teats (P= 0.04) and close to significance with affected teats (P = 0.06) in commercial populations. Haplotype analysis confirmed the tendency towards association with affected teats (P = 0.06) in the experimental DUMI population. The function, position, and associations shown here promote LEF1 as a candidate gene for number of teats and in particular for presence and number of inverted teats.

QTL for the heritable inverted teat defect in pigs

The mothering ability of a sow largely depends on the shape and function of the mammary gland. The aim of this study was to identify QTL for the heritable inverted teat defect, a condition characterized by disturbed development of functional teats. A QTL analysis was conducted in a porcine experimental population based on Duroc and Berlin Miniature pigs (DUMI). The significant QTL were confirmed by linkage analysis in commercial pigs according to the affected sib pair design and refined by family-based association test (FBAT). Nonparametric linkage (NPL) analysis revealed five significant and seven suggestive QTL for the inverted teat defect in the porcine experimental population. In commercial dam lines five significant NPL values were detected. QTL regions in overlapping marker intervals or close proximity in both populations were found on SSC3, SSC4, SSC6, and SSC11. SSC6 revealed QTL in both populations at different positions, indicating the segregation of at least two QTL. The results confirm the previously proposed polygenic inheritance of the inverted teat defect and, for the first time, point to genomic regions harboring relevant genes. The investigation revealed variation of the importance of QTL in the various populations due to either differences in allele frequencies and statistical power or differences in the genetic background that modulates the impact of the liability loci on the expression of the disease. The QTL study enabled us to name a number of plausible positional candidate genes. The correspondence of QTL regions for the inverted teat defect and previously mapped QTL for teat number are in line with the etiologic relationship of these traits.