Udder Massage Research Articles

The working process of the device for combined massage of the udder of heifers

The article discusses the concept of a unified approach to the development of pneumomechanical massage devices and milking machines. The practical implementation of this approach is considered. An improved pneumomechanical massage device is proposed. The main function is assigned to reduced pressure (vacuum) when performing technological operations of udder massage. The mechanical component of the device fulfils auxiliary function. The presence of an independent element in the suggested structural scheme of the device for the combined massage of heifers’ udders is substantiated. The change of pressure is fulfilled by a principle of counter-phase in a massage bell. This technical solution allows to increase efficiency of unloading cycle and to provide full restoration of blood circulation in the udder of an animal. The analysis of working process of the massage devices is carried out. An analysis of pressure changes in massage devices was made, a diagram of pressure changes in a massage bell and in a massage element of the device is drawn. The proposed design will eliminate the disadvantages of the device for pneumatic massage of the udder of heifers. The device allows regulation of pneumatic massage parameters for massage bell and massage element in limits of 20-25 and 40-48 kPa respectively.

THE IMPACT OF DIFFERENT PREPARATION TECHNIQUES FOR CALVING HEIFERS ON THEIR FUTURE DAIRY PRODUCTION

The article presents the results of research on the influence of duration of kneading of udder of springer heifers on further development of mammary gland and future productivity of cows. An important chain of effective dairy farming is the accurate organisation of herd reproduction, preparation of springer heifers for calving and lactation and milking of first calves. It has been determined that during the formation of productivity of dairy animals the first pregnancy has a decisive importance. The specific feature of this physiological state is that complex morphological and functional changes in the reproductive organs happen for the first time in the body, and pregnancy, calving and lactation proceed in the further formation of the animal organism. One of the most significant stressors on the first calving heifer's body is the first birth in combination with machine milking. The inability to overcome the influence of the first milking stress factor is the reason why some first calves are already being eliminated at this phase of the technological chain in commercial milk production. One of the techniques that can reduce the impact of the above mentioned stress factors is udder massage of springer heifers. To study effectiveness of manual massage of udder of springer heifers its duration (from 1 to 4 min.) was tested. There was also studied the effect of different durations of manual massage on the performance of heifers and their morphological traits. The experiment was carried out in SE "Ukrainka Slobodskaya" by IAS NAAS on animals of Ukrainian black-motley dairy breed. For that, five groups were formed with different duration of manual massage (I - 1min, II - 2min, III - 3min, IV - 4min, V - without massage). Massage was started in the 6th month of pregnancy. It was found that kneading of udder of springer heifers compared to no massage increased udder of first calving heifers according to the following measurements: udder girth by 17,4 - 18,7 % (P≤0,05), width 17,9 - 23,7 (P≤0,05), length 15,9 - 20,7 (P≤0,05), depth 16,1 - 20,8 (P≤0,05). It should be noted that using different time of hand massage (groups I-IV) positively shortens the time of litter secretion and increases milk production by 11.7 - 12.3%.

Effect of positive tactile stimulation and prepartum milking routine training on behavior, cortisol and oxytocin in milking, milk composition, and milk yield in Gyr cows in early lactation

Positive interactions with humans can improve cow behavior and facilitate farm management, especially in dairy production systems in which milking occurs daily. Therefore, this study aimed to investigate the impact of positive tactile stimulation on behavior, and its effect on the milking routine, milk ejection, and milk yield of Gyr cows. Experiment 1 was performed with 40 cows: 20 cows (5 primiparous and 15 multiparous) received positive tactile stimulation (by hands and brushes) in the aisle of the corral during the prepartum period for 14 days; the other 20 cows (5 primiparous and 15 multiparous) did not receive any kind of tactile stimulation (control). Experiment 2 was performed with 40 heifers: 20 heifers were trained to enter the milking parlor and were progressively submitted to positive tactile stimulation (by hands and brushes) and to the milking routine during the prepartum period in the milking parlor for 14 days; the other 20 heifers did not receive any kind of training or tactile stimulation (control). Behavioral data were observed during the beginning of lactation: when the animal entered the milking parlor (stalled, needed help, and attempted to escape), during milking preparation (reaction to udder massage and to the strip cup test), and during milking (reaction to teat cups and whether the animal pulled off the teat cups). Milk yield and residual milk volume were measured and milk samples were collected for analysis of milk composition, somatic cell count, and cortisol and oxytocin in milk. All the experimental cows were suckled on one teat by their calf. Entry into the milking parlor and preparation of the animal for milking are the most critical moments for detecting reactivity to milking procedures. At the same time, the two positive stimulations studied (i.e., handling in the corral or training in the milking parlor) were efficient in improving the behavior of Gyr cows at the beginning of lactation, thus demonstrating that prepartum positive stimulation was effective at reducing the negative behavior of cows during the firsts milkings. Indeed, the percentual of residual milk in primiparous cows subjected to positive milking training was significantly lower than those measured in untrained primiparous and multiparous cows. This result is very promising because it indicates that Gyr heifers, when positively stimulated and trained in the milking routine during the prepartum period, will maintain adequate behavior and excellent milk ejection during their firsts milkings.

Effect of litter size, milk replacer and housing on behaviour and welfare related to sibling competition in litters from hyper-prolific sows

Litter sizes where piglets are supernumerary to teats leads to the practice of fostering to nurse sows or to artificial rearing systems, which is associated with compromised welfare. An alternative strategy is to leave the supernumerary piglets with their own dam and provide milk replacer in the farrowing pen. To provide sufficient space around the sow’s udder, loose housing could be an alternative to the use of farrowing crates. However, large litters have been associated with increased teat fighting, abrasions on sows and piglets and signs of hunger. The aim of this study was to investigate whether provision of milk replacer and/or loose housing could alleviate signs of hunger and sibling competition at the udder. Ninety-eight litters were studied in a 2 × 2 factorial design. The sows were housed in crates or loose (CRATE/LOOSE), and litters had access to milk replacer or no milk replacer (+MILK/-MILK). The litter size was either 14 or 17 piglets on day 1 postpartum but decreased as piglets died. Recordings included drinking bouts of milk replacer, teat fighting, udder massage and abrasions on sow and piglets. On day 3, at least one observation of milk replacer consumption was observed in 90% of the litters in +MILK but at less than five bouts per litter/12 h in all except two litters. On days 7, 14 and 21, 59-65% of the piglets in +MILK consumed milk replacer at least once with a mean frequency of 0.4-1.9 bouts/h/piglet. Increasing litter size resulted in more piglets involved in teat fighting, having low suckling success and snout abrasions (P < 0.05). The risk for all indicators were generally higher for smaller compared to larger piglets. Access to milk replacer reduced risk of piglet snout abrasions (P < 0.05), but not of teat fighting (P> 0.1). Loose housing reduced the risk of udder abrasions (P < 0.05) and tended to decrease udder massage (P < 0.10). Thus, milk replacer and loose housing minimally reduced litter competition in litters from hyper-prolific sows, indicating that supplementing large litters with milk replacer can be associated with compromised welfare. The welfare consequences of using milk replacer appear comparable to when surplus piglets are fostered by nurse sows or artificially reared. Before supplementing milk replacer to large litters is further applied under commercial conditions, research and innovation is needed to improve quality of milk replacer and cup design to alleviate the negative impact on welfare.

Biological features of cows with different levels of stress resistance

The results of studies of biological features of 66 cows of Holstein breed with different reaction levels to stress have been quoted. The stress factor was the planned blood taking from them. In an hour after this procedure, blood was taken again from the jugular vein with the aim to determine the concentration of cortisol in experimental animals. Based on the different cortisol concentration in blood, the cows have been differentiated into three gro ups: I – with high stress resistance, II – with medium stress resistance and III – with low stress resistance. The aim of the studies was to establish the relationship between the different stress resistance in animals and the development and function of the udder, the milk productivity and the heat resistance of the organism under summer temperature loading in the conditions of Ukraine. It has been established that the animals of group I were milked in double-quick time (P <0.001), and their milk-ejection rate was 1.4 kg/min (P <0.001) compared to the third group. They also had a higher reaction rate at the beginning of milking (P <0.001). The parts of the udder in the cows of this group are more evenly developed, which serves as the best precondition for the implementation of the milk flow reflex by machine milking. Cows with low stress resistance have a well-defined prolonged latent period at the beginning of machine milking. This is explained by the delay in the reaction of their mammary gland in response to the beginning of milking. It has been suggested that this disadvantage can be mitigated by using a more improved milking equipment, with an udder massage regime, which is capable to compensate the disturbance of the milk yield reflex in cows, which are more sensitive to stress. The influence of different stress resistance on fat and protein content in the milk of Holstein cows has not been properly defined. But in comparison with low stress-resistant animals, milk yields for 305 days of the first lactation were higher in highly stress-resistant animals – by 639 kg (P <0.001), in cows of the middle group – by 216 kg (P <0.05). The lower resistance of cows to stress makes them vulnerable in conditions of temperature load during the hottest months (July, August) of the summer period in Ukraine. Their body reacts to such a load with sharper fluctuations in body temperature, pulse, respiration rate and thermal sensitivity index as compared to their peers with high level of stress resistance (P <0.01...0.001). To solve this problem with trans-humance grazing it is possible to use mobile canopies.

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.

Factors Associated with Hygienic Quality of Bulk Tank Milk Produced in Central Poland

Factors Associated with Hygienic Quality of Bulk Tank Milk Produced in Central PolandThe aim of this study was a complex analysis of organizational and technological factors affecting somatic cell count (SCC) and total microorganism count (SPC) in bulk tank milk produced in the area of Łódź Voivodeship. The study was conducted on the basis of a questionnaire completed directly in 205 family farms, maintaining Polish Black-and-White Holstein-Friesian cows. The data were analysed statistically using multifactor analysis of variance. The following factors decreased SCC in milk: application of mechanical ventilation in the cowshed; disinfection of stalls for cows; frequent inspection of milking equipment efficiency by a specialized service (twice vs. once a year); application of manual pre-milking udder massage; dry period of a standard length of 6-8 weeks (vs. 2-5 weeks); application of concentrates in amounts of at least 3 kg/day/cow; application of meadow hay and straw or hay only among roughages in cow feeding (vs. straw only); addition of vitamin E and Cu to feeding ration for cows and individual housing of replacement heifers between 1-3 months of age (vs. group system). In turn, the following factors decreased SPC: participation of milkers in specialist trainings; cleaning of teats before milking using wet towel or washing with water containing a disinfectant; "dry" storage of milking equipment between milkings; culling of cows due to mastitis; application of vitamin A and Zn; no use of milk from mastitic cows in calf feeding; and individual housing of replacement heifers during the first month of life.

Efeito da massagem do úbere ao final da ordenha no leite residual e na ocorrência de mastite em vacas leiteiras

Effect of udder massage at the end of milking on residual milk and mastitis occurrence in dairy cows. Residual milk (RM) after milking is an important factor that can predispose cows to mastitis. In this study, the hypothesis that udder massage at the end of milking may reduce RM and the incidence of mastitis was tested in two experiments. Experiment 1 was conducted on an experimental farm with ten lactating cows (6,200kg/lactation) and experiment 2 was carried out on a commercial farm with 52 lactating cows (4,480kg/lactation). In both experiments the cows were paired by parity, stage of lactation and productivity, and they were randomly assigned to one of the treatments: massage or no massage of the udder at the end of milking, in two periods in a crossover design. The individual milk production of each cow was measured. Residual milk was collected and measured 2min after an oxitocin application. California Mastitis Test was used to detect the occurrence of subclinical mastitis. In neither of the experiments did udder massage have any effect on milk production (experiment 1 p &gt; 0.41, n = 10 and experiment 2 p &gt; 0.46, n = 12), on RM (experiment 1, 1.78 ± 0.45kg, n = 10; experiment 2, 2.42 ± 0.32kg, n = 12), or on mastitis incidence (experiment 2, chi-square; DF = 1; p &gt; 0.68, n = 26). We conclude that udder massage at the end of milking has no effect on RM and does not affect mastitis incidence, at least under the conditions used in these experiments.

Parent–offspring resource allocation in domestic pigs

Behavioural research on domestic pigs has included parent–offspring conflict, sibling competition, and the use of signals which influence resource allocation. In this paper, we review key sow–piglet behavioural studies and discuss their relevance to resource allocation theory. Sibling competition begins in the uterus and continues after birth, as piglets compete directly for access to the sow’s teats. This competition is made more severe by a unique dentition, which newborn piglets use to lacerate the faces of siblings during teat disputes. Competition often leads to the death of some littermates, especially those of low birth weight. Piglets also compete indirectly for milk, apparently by stimulating milk production at the teats that they habitually use at the expense of milk production by other teats. The complex nursing behavior of the sow appears designed to prevent the more vigorous piglets from monopolizing the milk. Sows give vocal signals which both attract piglets to suckle and synchronize their behavior during nursing episodes. Piglets give loud vocal signals when separated from the sow; calls which vary in intensity and appear to be honest signals of need. Udder massage by piglets may also serve as an honest signal of need. Parent–offspring conflict has been demonstrated experimentally in pigs. Specifically, when given the opportunity to control contact with their piglets, sows nurse less frequently, provide less milk, and lose less weight during lactation than sows that cannot control their level of contact. Because of this interesting natural history and because they are so amenable to experimentation, domestic pigs provide a rich system for testing ideas drawn from resource allocation theory.

Mammary development and milk production in the sow: Effects of udder massage, genotype and feeding in late gestation

The primary aim of the study was to investigate whether post-ejection udder massage 1–2 weeks pp (post partum) had an effect on the amount of mammary tissue and milk production in the domestic sow. The nursing behaviour of 35 primiparous LYL or YLY sows and their litters was followed on days 7 and 14 pp. The milk production was measured by the weigh–suckle–weigh method of the whole litter on days 11 and 18 pp. After weaning on day 28 pp, the sows were slaughtered and the mammary tissue excised and weighed. No significant correlations were found between the duration of post-ejection udder massage and the subsequent milk production. LYL sows had more mammary tissue ( P < 0.05) and their piglets spent more time performing post-ejection udder massage compared to the YLY sows ( P < 0.01). Individual variation was found in the proportion of time that the sows were lying on either their right or left side. The weight of the mammary tissue from the left side was positively affected by the amount of udder massage (pre- and post-ejection massage) that the sows had received while lying on the right side relative to the amount that she had received while lying on the left side on day 7 pp ( P < 0.01). In conclusion, the intensity of udder massage influenced the amount of mammary tissue at slaughter. The genotype of the sow affected the expression of nursing behaviour and milk production. No connection was found between post-ejection udder massage and the measures of milk production 1–2 weeks pp. Finally, feeding during the last half of gestation affected the nursing behaviour.

The effect of two piglet teeth resection procedures on the welfare of sows in farrowing crates. Part 2

Recent EU legislation discourages the practice of resecting piglets’ needle teeth. However, the effect of leaving piglets’ teeth intact on the welfare of sows in farrowing crates is poorly understood. Therefore, the aim of the study was to compare the effects of clipping and grinding piglets’ needle teeth, compared to leaving them intact, on the welfare of sows in farrowing crates. Six days pre-partum 60 multiparous sows were assigned to one of three treatments. Litters had their teeth clipped (C), ground (G) or left intact (I) at birth. Sows’ teats were inspected for lesions pre-partum (day −3) and on days 1, 4, 11, 18 and 27 post-partum. Instantaneous scan samples (5 min intervals) of sow behaviour were carried out during three 2 h periods on days 1, 4, 8, 14, 21 and 26. On days 1, 4 and 11 all piglets were removed from the crate for 60 min. On re-introduction of the piglets, sow maternal behaviour was recorded continuously for 20 min. The number of sows with teat lesions tended to differ between treatments on days 11 ( P = 0.06) and 18 ( P = 0.10). There was an interactive effect between treatment and day on sow dog-sitting behaviour throughout lactation ( P < 0.001) and a tendency for an interactive effect on posture-changing behaviour ( P = 0.08). On day 21, I sows were dog-sitting in more observations than C sows ( P < 0.05) and on day 26 in more observations than C and G sows ( P < 0.001). There was an interaction between treatment and day in the latency of sows to suckle their piglets following 60 min separation ( P < 0.05). On day 4, I sows had a shorter latency to suckle than C and G sows ( P < 0.05). There was an effect of treatment on the number of sows that terminated bouts of post-suckling udder massage ( P < 0.05). On day 4, more I than C sows terminated post-suckling udder massage ( P = 0.01). Finally, there was an effect of treatment on the time spent lying in the ventral posture in the observations of maternal behaviour ( P < 0.05). C sows spent less time lying in the ventral posture than G and I sows ( P < 0.05). There were indications that leaving the teeth intact and to a lesser extent grinding caused injury and disturbance to sows. In farrowing crates, leaving piglets’ teeth intact cannot be recommended.

Factors affecting somatic cell count in cow bulk tank milk--a case study from Poland.

The aim of this paper was a retrospective analysis of factors affecting the somatic cell count (SCC) in cow bulk tank milk. The investigations concerned the year 2000 and were conducted on 212 family dairy farms in the Wielkopolska region (Western Poland). The average herd size was 13.3 cows (ranging from 5 to 48), whereas the mean SCC was 269,000 in 1 cm3 of milk (ranging from 63,000 to 631,000). In the period from July to September a higher SCC (P < or = 0.01) was found than in the other months. In herds of more than 15 cows, higher SCC values (P < or = 0.05) were observed than in the smaller herds. The following management and technological factors significantly decreased SCC: a 7-8-week dry period (versus shorter period), foremilking with the use of a forestripper, practicing manual udder massage before milking, individual rationing of feeds according to production, and the application of MgO and beta-carotene additives to the feed ration.

Oxytocin, prolactin and somatostatin in lactating sows: associations with mobilisation of body resources and maternal behaviour

The aim of the present study was to investigate how oxytocin, prolactin and somatostatin during nursings relate to maternal characteristics of sows. Undisturbed nursing behaviour and sow–piglet nasal contacts of 21 lactating sows were recorded on day 13 of lactation, and hormonal status was assessed during three successful nursings on day 14. Piglet and litter growth (days 8–15), sow weight loss (days 1–15) and catabolic state (measured as NEFA on day 7), as well as number of successful nursings on day 13 were used as measures of mobilisation of sow body resources. Nasal contacts and sow behaviour facilitating udder massage were used as measures of positive piglet-directed behaviours. Concentrations of oxytocin were higher, those of prolactin lower and those of somatostatin similar during nursings compared to samples taken 15 min after nursing. Oxytocin peaked during most nursings and prolactin increased gradually after nursings. Non-nursing oxytocin values were positively correlated with the proportion of sow-terminated nursings but not with other measures of piglet-directed behaviour. Non-nursing oxytocin concentrations were positively correlated with piglet weight gain and concentrations of oxytocin during nursings were correlated with NEFA and sow weight loss. Our results indicate that oxytocin might have more than merely an all-or-nothing function in triggering milk ejection. Oxytocin seems to be quantitatively related to efficiency of milk production, although the present study design does not allow for speculation on causal relationships.

NURSING BEHAVIOUR AND NURSING VOCALISATIONS IN DOMESTIC SOWS: REPEATABILITY AND RELATIONSHIP WITH MATERNAL INVESTMENT

We examined the repeatability of pig nursing behaviour and its relationship with maternal investment (measured in piglet growth) in two experiments. In Experiment 1, eleven sows were followed for 2-5 (median 3) lactations, and their nursing behaviour was recorded on Day 11 post partum during each of these lactations. In Experiment 2, fourteen sows were followed for two consecutive lactations, and their nursing behaviour recorded on Days 7 and 28. In Experiment 2, the data on piglet growth between Days 1 and 6, and between Days 6 and 28 were also recorded, and mortality data were available in both experiments. We evaluated the data in order to get answers to three basic questions: First, was the nursing behaviour repeatable within and across lactations, i.e. did the sow have individually stable nursing styles? Second, was the variability in nursing behaviour related to piglet growth or mortality? Third, were the sows inclined to nurse repeatedly on one side and if so, did this result in faster growth and/or lower mortality in the piglets suckling the 'upper row' teats? We found that the pattern of grunting vocalisation emitted by the sow was highly repeatable both within and across lactations. We hypothesise that this individual acoustic signal may be used by piglets to locate their mother during synchronised nursings in the group living female pigs. However, the variables characterising nursing frequency, the willingness of the sow to allow udder massage by the piglets, and the laterality of nursing had low or no repeatabilities within and across lactations. Piglet growth was only loosely, and piglet mortality not at all, related to the quantitative variability in nursing behaviour casting doubts on whether nursing behaviour variables are suitable for selection programs. Although some sows preferred to nurse while lying on the left, and others on the right side, this laterality did not result in faster growth of piglets suckling the upper row of teats.

VOCALIZATIONS AROUND THE TIME OF MILK EJECTION IN DOMESTIC PIGLETS: A RELIABLE INDICATOR OF THEIR CONDITION?

Abstract In some nursings, piglets initiate nose contacts with their mother and emit typical 'croaking' vocalizations. We examined whether the croaking vocalizations reflect the condition of the piglets and whether the sows increase their maternal investments in response to those vocalizations. The following predictions were tested: (i) Piglets with lower weight gain should vocalize more than piglets with higher weight gain; (ii) piglets' milk intake is lower in those nursings in which they vocalize after milk ejection; (iii) piglets make more croaking vocalization in nursings which were preceded by longer intervals since the last nursing with milk ejection; (iv) sows permit longer post-ejection massage in nursings in which piglets vocalized immediately after milk ejection; (v) sows decrease the interval until the succeeding nursing after those nursings in which the piglets have vocalized. Hypotheses (i) and (ii) were investigated by controlling the inter-nursing intervals in 14 sows and recording the milk intake of individual piglets' over 24 hours during days 7 or 8 post partum (Experiment 1). Hypotheses (iii) to (v) were examined through analysing video recordings of undisturbed six h nursing sequences in 29 sows (Experiments 2 and 3). The majority of our predictions were not confirmed: piglets did not vocalize more (either before or after milk ejection) after longer intervals since last milk ejection; they did not vocalize more in nursing in which they received less milk; and it was not the piglets or the litter with a lower milk intake or lower weightgain that emitted more vocalization. Neither of our predictions regarding the influence of croaking vocalizations on maternal investment was confirmed. The vocalizations were in no way associated with the length of the following inter-nursing interval or with the permission of longer udder massage. To conclude, piglet croaking vocalizations during nursings are not reliable indicators of piglet condition and are not used by sows to adjust their maternal investment.

Prolactin and insulin levels in lactating sows in relation to nursing frequency☆

It has been established that sows up- or down-regulate their milk production as the frequency of nursings is changed. The amount of udder massage by piglets might also influence milk production. To investigate whether these effects are associated with changes in prolactin or insulin levels, we enforced five sows each to nurse either every 35 min (MIN35) or every 70 min (MIN70) over a 26- to 28-hr period. Milk production was measured during the first 24 hr of this period. During the last three to four nursings, blood was collected every 5 min. Plasma prolactin levels increased after milk ejection (P < 0.05), whereas insulin levels increased only briefly in MIN70 sows. Sows nursing every 35 min had lower basal (P < 0.001) and maximal (P < 0.05) concentrations of insulin than MIN70 sows. There were no differences between the two groups in prolactin levels. Nursings with a postejection udder massage longer than 90 s tended to induce a higher increase in prolactin (P < 0.1) than nursings with a shorter massage. When the effects of imposed nursing frequency were removed, there was an across-sows positive residual correlation between average prolactin levels (P < 0.05) and the duration of post-ejection udder massage during the preceding 24 hr. We conclude that when milk production of a sow is changed by altering the nursing frequency within natural limits, the necessary alteration in catabolic state of energy metabolism may be associated with altered insulin levels. The duration of udder massage in a single nursing might have only a slight immediate impact on prolactin levels, but may influence prolactin levels more substantially if increased for a period of 24 hr.

Predictability of nursings without milk ejection in domestic pigs

Up to 30% of nursings in domestic pigs do not result in the let-down of milk (non-nutritive nursings). The motivation to nurse often seems to be similar in non-nutritive and nutritive nursings; the sow exposes the udder and begins to grunt rhythmically while the piglets massage the teats intensively. The question arises, whether the behaviour of the piglets and sow is indeed the same during nutritive and non-nutritive nursings. We investigated quantitatively whether the latency to start teat massage, the proportion of piglets participating in the nursing, the intensity of teat massage (in terms of snout movement frequency) by the piglets and the grunting rate by the dam differ between nutritive and non-nutritive nursings. These behavioural characteristics were compared between videotaped nutritive and non-nutritive nursings in 7 sows and their litters at the age of 7–8 days after farrowing. Teat massaging movements and sows' grunts were counted during periods of 40 s one minute before (Period 1) and one and a half minute after the milk ejection (Period 2) in nutritive nursings, and during the same periods, calculated from the start of the nursing, in non-nutritive nursings. Grunting frequency was also assessed during 30 s before and 30 s after the start of the udder massage. The latency to start teat massage by the piglets and their participation in the massage were the same in nutritive and non-nutritive nursings. During Period 1 teat massage intensity did not differ between nutritive and non-nutritive nursings (13.2 vs. 18.7 snout movements, paired t-test, p=0.23), but it did differ during Period 2 (20.9 vs. 12.5, paired t-test, p=0.024). The sow's grunting frequency was similar in the two types of nursings both before (0.27 grunts per second in nutritive, 0.22 in non-nutritive nursings, paired t-test, p=0.216) and after the start of udder massage (0.47 vs. 0.35 grunts/s, p=0.148). In nutritive nursings, the grunting increased further to 0.74 grunts/s in Period 1 ( p=0.005), whereas in non-nutritive nursings, it remained at 0.34 grunts/s. We conclude that both the sow and her litter enter non-nutritive nursings with full motivation to accomplish a complete nursing, and it is not until the initial massage is in full progress that it is revealed in the sow's grunting that the milk ejection will fail.

The use of a rooting substrate by fifteen day old piglets

The ingestion of creep feed by piglets depends upon them displaying suitable exploratory behaviours away from the sows udder. However, sows milk has an excellent FCR and it may be argued that, where the udder is available, exploration away from it is a failure to optimise the use of available food resources. A corrolary to this is that those piglets displaying exploratory behaviour away from the sows udder will be those piglets for which further udder massage shows no net gain i.e. those exploiting the maximum potential of the udder and those for whom the udder shows very little benefit. The former group will be characterised by heavier weights and faster growth rates. The latter group will be characterised by lighter weights and slower growth rates. It may be assumed that animals exist on a continuum between these two states. In commercial conditions the latter group is typically fostered off or culled. This project tested the hypothesis that, in healthy litters (thus excluding the latter group), exploratory behaviour away from the udder will be displayed proportional to the weight of the piglet.

The use of a rooting substrate by fifteen day old piglets

The ingestion of creep feed by piglets depends upon them displaying suitable exploratory behaviours away from the sows udder. However, sows milk has an excellent FCR and it may be argued that, where the udder is available, exploration away from it is a failure to optimise the use of available food resources. A corrolary to this is that those piglets displaying exploratory behaviour away from the sows udder will be those piglets for which further udder massage shows no net gain i.e. those exploiting the maximum potential of the udder and those for whom the udder shows very little benefit. The former group will be characterised by heavier weights and faster growth rates. The latter group will be characterised by lighter weights and slower growth rates. It may be assumed that animals exist on a continuum between these two states. In commercial conditions the latter group is typically fostered off or culled. This project tested the hypothesis that, in healthy litters (thus excluding the latter group), exploratory behaviour away from the udder will be displayed proportional to the weight of the piglet.

Influence of massage during simulated non-nutritive nursings on piglets' milk intake and weight gain

Two experiments were conducted with the aim of investigating whether non-nutritive nursings (nursings without milk ejection), when included into a regular rhythm of nursings with milk ejection, affect milk intake and body weight gain during early lactation in pigs. In experiment 1, when the piglets were 9 to 12 days old, 8 sows were forced to nurse every 70 min three times in succession. Between the nursings, 2 piglets had an additional opportunity to massage the sow's teats from which they had been suckling. Milk intake was estimated by the weigh-suckle-weigh method. Additional massage on the two teats had no influence on milk output from those teats on subsequent nursings. In experiment 2, on day 7 or 8 post partum 16 sows were forced to nurse at every 70 min for a period of 24 h. In nine of the sows (group MIN70 + 15), non-nutritive nursing were induced 15 min after each nutritive nursing. In the other group of seven sows (MIN70), there was no opportunity for this additional massage. The total duration of udder massage was considerably longer in group MIN70 + 15 (median 271 min vs. 165 min, Mann-Whitney U-test, p < 0.005) than in the other group that did not have the additional massage. Nevertheless, the weight gain during the whole 24 h period was the same in both groups (157 g vs. 141 g, Mann-Whitney U-test, n.s.). Both groups had nearly the same decrease in weight during the 24 h manipulation of nursing rhythm in comparison with the weight gain during a unmanipulated period 24 h one day before (group MIN70 + 15 decreased 28% and group MIN70 decreased 31%, Mann-Whitney U-test, n.s.). The results suggest that additional massage provided during non-nutritive nursings does not induce higher milk output during subsequent milk ejection, either locally or systemically.