Abrupt Weaning Research Articles

Effect of abrupt weaning at housing on leukocyte distribution, functional activity of neutrophils, and acute phase protein response of beef calves.

BackgroundSixteen, spring-born, single suckled, castrated male calves of Limousin × Holstein-Friesian and Simmental × Holstein-Friesian dams respectively, were used to investigate the effect of weaning on total leukocyte and differential counts, neutrophil functional activity, lymphocyte immunophenotypes, and acute phase protein response. Calves grazed with their dams until the end of the grazing season when they were housed in a slatted floor shed. On the day of housing, calves were assigned to a treatment, (i) abruptly weaned (W: n = 8) or (ii) non-weaned (controls) (C: n = 8). Weaned calves were housed in pens without their dams, whereas non-weaned (control) calves were housed with their dams. Blood was collected on day -7, 0 (housing), 2, 7, and 14 to determine total leukocyte and differential counts and concentration of fibrinogen and haptoglobin. Lymphocyte immunophenotypes were characterised using selected surface antigens (CD4+, CD8+, WC1+ (γδ T cells), MHC Class II+ lymphocytes), and the functional activities of neutrophils (surface expression of L-selectin (CD62L), phagocytic and oxidative burst activity) were investigated using flow cytometry.ResultsTreatment × sampling time interactions (P < 0.05) were detected for total leukocyte and neutrophil counts, all lymphocyte subsets, mean fluorescence intensity of CD62L+ neutrophils, and percentage neutrophils performing phagocytosis. On d 2, total leukocyte and neutrophil count increased (P < 0.001), and percentage CD4+ and CD8+ lymphocytes, percentage phagocytic neutrophils, mean fluorescence intensity of CD62L+ neutrophils decreased (P < 0.05) in W compared with baseline (d 0), whereas they were unchanged (P > 0.05) in C. On d 2, percentage WC1+ lymphocytes decreased (P < 0.05), whereas percentage MHC class II+ lymphocytes increased (P < 0.05) in W and C, however the magnitude of change was greater in W than C. There were no treatment × sampling time interactions (P > 0.05) for monocyte, eosinophil, and basophil counts, percentage G1+ neutrophils, or percentage oxidative burst positive neutrophils.ConclusionsAbrupt weaning resulted in increased neutrophil counts and impaired trafficking and phagocytic function. Together with the changes in lymphocyte subsets, the results suggest that there was a greater transitory reduction in immune function at housing in abruptly weaned than non-weaned beef calves.

Characterisation of physiological and immunological responses in beef cows to abrupt weaning and subsequent housing.

BackgroundWeaning involves the permanent separation of the calf from the dam and has been shown to be stressful for both. The objectives of this study were to characterise the effect of i) abrupt weaning and ii) subsequent housing on the extended physiological and immunological responses of beef cows. At weaning (day (d) 0, mean age of calf (s.d.) 212 (24.5) d), cows were abruptly separated from their calves and returned to the grazing area. After 35 d at pasture, cows were housed in a slatted floor shed and offered grass silage ad libitum plus a mineral-vitamin supplement daily. Rectal body temperature was recorded and blood samples were obtained on i) d 0 (weaning), 2, 7, 14, 21, 28, 35 and subsequently on ii) d 0 (housing), 2, 7, 14 and 21 for physiological, haematological and immunological measurements.ResultsPost-weaning, concentration of cortisol and dehydroepiandrosterone were unchanged (P > 0.05). Rectal body temperature, neutrophil number and neutrophil: lymphocyte ratio increased (P < 0.01) on d 2 compared with pre-weaning baseline. Lymphocyte and neutrophil number decreased (P < 0.05) on d 2 to 7 and d 7 to 21, respectively, compared with pre-weaning baseline. Interferon-γ production decreased (P < 0.05) on d 2 compared with pre-weaning baseline. An increase (P < 0.05) in acute phase proteins, fibrinogen and haptoglobin was evident on d 2 to 35 compared with pre-weaning baseline. Concentration of glucose increased on d 2 to 28, whereas non-esterified fatty acid decreased on d 2 to 35 compared with pre-weaning baseline. Post-housing, concentrations of cortisol, rectal body temperature, total leukocyte number, and glucose were unchanged (P > 0.05). On d 2 post-housing, neutrophil number and neutrophil: lymphocyte ratio increased (P < 0.05), whereas lymphocyte number and concentrations of dehydroepiandrosterone, fibrinogen and non-esterified fatty acid decreased (P < 0.05) compared with pre-housing baseline. Concentration of haptoglobin increased (P < 0.05) on d 14 to 21 post-housing.ConclusionsA transitory increase in neutrophil number and decrease in lymphocyte number, increased neutrophil:lymphocyte ratio coupled with decreased interferon-γ production, and increased concentration of acute phase proteins indicate a stress response in cows post-weaning, whereas post-housing, changes were less marked.

Prenatal flavor exposure affects growth, health and behavior of newly weaned piglets

Young animals can learn about flavors from the maternal diet that appear in the amniotic fluid and mother's milk, which may reduce neophobia for similarly flavored food types at weaning. Flavor learning may be beneficial for piglets, which after the rather abrupt weaning in pig husbandry frequently show a period of anorexia, reduced health, and stress-induced behaviors. We investigated the effects of pre- and postnatal flavor exposure through the maternal diet on acceptance of a similarly flavored food and subsequent growth, health and behavior of newly weaned piglets. Sows were offered anise-flavored (F) or control (C) food during late gestation. Piglets were cross-fostered after birth, with each sow fostering 5 piglets from an F sow and 5 from a C sow. During lactation, sows were offered F or C food, resulting in FF, CF, FC and CC piglets. Piglets were weaned on day 25 and were given both control and flavored food for two weeks using a double food choice approach. The flavored food was not preferred. Yet, prenatally exposed animals showed a higher food intake and a higher body weight in the first days after weaning, and a lower occurrence of diarrhoea than non-exposed piglets. Prenatal exposure also increased the latency to fight, and reduced oral manipulation of pen mates and mounting during the first two weeks after weaning. Prenatal exposure, but not postnatal exposure alone, to anisic flavor through the maternal diet reduced weaning-associated problems in piglets and enhanced their health and welfare in the period after weaning.

Effects of Early, Abrupt Weaning on HIV-free Survival of Children in Zambia

Effects of Early, Abrupt Weaning on HIV-free Survival of Children in Zambia

Duration of weaning, starter intake, and weight gain of dairy calves fed large amounts of milk

When calves are weaned abruptly off large amounts of milk, weight gain is reduced as a result of low intake of starter. We compared gradual and abrupt weaning of 40 calves allowed to drink up to 12kg of milk/d by automated feeders, housed in groups of 4, and weaned at 41 d abruptly or over 3 gradual weaning periods (4, 10, or 22 d), with one calf within each group randomly allocated to each treatment, balancing for sex and birth weight. During the milk-feeding period, the calves weaned over 22 d drank the least milk and ate the most starter, but these calves had the lowest total digestible energy intake and weight gains. The abruptly weaned calves had the highest digestible energy intakes and weight gains during the period before weaning. During the 9 d following weaning, the calves weaned over 22 and 10 d ate more starter and had better weight gains than abruptly weaned calves and those weaned over 4 d. Abruptly weaned calves lost weight during this period. In summary, gradual weaning improved starter intake, but because of reduced milk availability, this resulted in reduced total digestible energy intake before weaning. Weaning over 10 d resulted in the best overall weight gains over the study.

The effects of alternative weaning methods on behaviour in beef calves

The aim of this experiment was to compare the behavioural responses and weight change of beef calves weaned using three weaning methods. Forty-eight primiparous Hereford or Hereford × Angus nursing beef calves (180.7 ± 1.3 days old; mean ± SEM) were assigned to one of three treatments: 1) CON: weaned abruptly on day 0; 2) FEN: calves were separated by fence line from dams on day − 17 but remained in visual sight of one another; or 3) NF: cows and calves remained together but suckling was prevented on day − 17 by inserting a nose-flap anti-suckling device. In all treatments remote physical separation of the cow and calf took place on day 0. Behaviours were recorded by instantaneous sampling from day − 20 to day − 13, and from day − 3 to day 5, except on day 0. Distance between cows and calves and the fence line in FEN calves and between the dyads in NF calves were recorded from day − 17 to day − 13. Body weights of calves were recorded on days − 24, − 11, 0, 7 and 21. There was a day and treatment by day interaction for all behaviours. Behavioural responses were strongest during the first 2 days after fence line separation in the FEN calves and after remote separation in the CON calves. For the NF calves, behavioural effects were observed immediately after insertion of the nose-flaps, including numerous unrewarded suckling events, and again when remote physical separation took place. Overall the FEN calves vocalized ( P < 0.03) more than CON and NF calves. CON calves played ( P < 0.02) and ruminated ( P < 0.04) more often than FEN and NF calves, and walked ( P = 0.01) more than NF. On day − 17 and day − 16, FEN calves (and their dams) spent more time within 30 m of the fence line than on day − 15 to day − 13 ( P < 0.02). NF calves spent more time in close proximity of their dams on day − 17 and day − 16 ( P < 0.001). Calves of the CON treatment had a greater average daily gain (ADG) than FEN and NF calves ( P < 0.008); ADG was greater in FEN than in NF calves ( P = 0.02). Two-stage weaning with nose-flaps resulted in a second distress response after remote physical separation from the dam, and a drop in ADG in both periods indicating that the response was distributed between the two stages. In calves weaned using the fence line method, the response was more prolonged and more intense, with no advantages for weight gain compared to abrupt weaning. In conclusion, the two alternative weaning methods did not appear to provide any clear benefits in reducing weaning distress in beef calves compared to abrupt weaning in the conditions used in this experiment. However, the use of nose-flaps seems to reduce distress better than fence line separation.

Abrupt Weaning Significantly Increases Mortality Following a Secondary Bacterial Respiratory Infection

Secondary bacterial respiratory infections are a major cause of mortality in fall-weaned feedlot calves, and epidemiological studies implicate a variety of stressors as significant contributing factors. Experimental studies have identified stressors that may compromise pulmonary defense mechanisms but there is no evidence that these functional changes alter respiratory disease outcome. We used a model of combined viral and bacterial respiratory disease to determine if nutritional and psychological stressors (abrupt weaning; AW) altered respiratory disease mortality. Mortality was doubled in AW calves challenged with Mannheimia haemolytica four days after a primary bovine herpesvirus-1 (BHV-1) respiratory infection, when compared to calves adapted to weaning (pre-conditioned; PC) for two weeks prior to respiratory challenge. Reduced survival time and decreased lung pathology in the AW group suggested death was due to an acute systemic reaction. Viral shedding did not differ significantly between the two treatment groups. AW calves and all calves developing fatal pneumonia had significantly elevated interferon (IFN)-y levels in nasal secretions and increased systemic proinflammatory responses. Analysis of blood leukocytes revealed significantly increased CD14 and TLR4 gene expression in animals with fatal pneumonia. These analyses support the conclusion that stress enhanced innate immune responses to viral infection without altering the level of BHV-1 infection. These studies provide the first quantitative evidence that stress associated with abrupt weaning contributes significantly to fatal bovine respiratory disease.

Breast feeding: A time to craft new policies

New studies of breastfeeding have discovered or confirmed the benefits to mother and child. They reinforce an emphasis on exclusive breastfeeding - no other food or fluids - during the first 6 months. Studies include findings from across the world, in well-resourced and poorly resourced settings. They also emphasize longer duration of breastfeeding, into the second year of life, and gradual rather than abrupt weaning. For HIV-infected mothers, the dangers of non-exclusive feeding in the first half year of life have been well documented in recent publications. Other studies open up the possibilities for antiretroviral treatment to accompany breastfeeding, whether given to the mother, or child, or both. To be effective, implementation of any recommendations must consider individual, family, and community resources.

Differential Effects of Early Weaning for HIV-Free Survival of Children Born to HIV-Infected Mothers by Severity of Maternal Disease

BackgroundWe previously reported no benefit of early weaning for HIV-free survival of children born to HIV-infected mothers in intent-to-treat analyses. Since early weaning was poorly accepted, we conducted a secondary analysis to investigate whether beneficial effects may have been hidden.Methods958 HIV-infected women in Lusaka, Zambia, were randomized to abrupt weaning at 4 months (intervention) or to continued breastfeeding (control). Children were followed to 24 months with regular HIV PCR tests and examinations to determine HIV infection or death. Detailed behavioral data were collected on when all breastfeeding ended. Most participants were recruited before antiretroviral treatment (ART) became available. We compared outcomes among mother-child pairs who weaned earlier or later than intended by study design adjusting for potential confounders.ResultsOf infants alive, uninfected and still breastfeeding at 4 months in the intervention group, 16.1% who weaned as instructed acquired HIV or died by 24 months compared to 16.0% who did not comply (p = 0.98). Children of women with less severe disease during pregnancy (not eligible for ART) had worse outcomes if their mothers weaned as instructed (RH = 2.60 95% CI: 1.06–6.36) compared to those who continued breastfeeding. Conversely, children of mothers with more severe disease (eligible for ART but did not receive it) who weaned early had better outcomes (p-value interaction = 0.002). In the control group, weaning before 15 months was associated with 3.94-fold (95% CI: 1.65–9.39) increase in HIV infection or death among infants of mothers with less severe disease.ConclusionIncomplete adherence did not mask a benefit of early weaning. On the contrary, for women with less severe disease, early weaning was harmful and continued breastfeeding resulted in better outcomes. For women with more advanced disease, ART should be given during pregnancy for maternal health and to reduce transmission, including through breastfeeding.Trial RegistrationClinical trials.gov NCT00310726

Effect of weaning dairy-bred bull calves either gradually or abruptly

There are four main parameters to determine weaning time with artificially reared dairy-bred calves: age, liveweight, concentrate intake and milk price. Most commercial calf rearers use concentrate intake as the main method weaning calves when eating 1kg of concentrates per day. Calves can be weaned either abruptly or gradually where the quantity and strength of milk replacer is reduced over a period of time. The objective of this experiment was to evaluate the effect of gradual or abrupt weaning strategies for calves weaned at 42 days of age.

Responses to multiple chain enrichment in post weaned pigs

The social stressors associated with the abrupt weaning process on commercial farms can result in significant welfare issues for pigs; including behavioural problems and aggression, decreased immunological responses, reduced live weight gain and efficiency of feed conversion (van de Weerd and Day, 2008). Slats and slurry systems in commercial housing systems for grower pigs provide a barren environment which may exacerbate these problems. Enriched environments have been shown to reduce aggression in pigs, particularly where devices that have manipulative and destructive properties are used (Scott et al, 2007). However, studies often include a single device that does not permit all animals to interact with the enrichment at any one time. The aim of the present study was to investigate the effects of multiple metal chain enrichment on levels of aggression in growing pigs.

Effects of Alternate Weaning Methods on Behavior, Blood Metabolites, and Performance of Beef Calves

Beef calves traditionally are weaned by abrupt remote separation from their dams. Alternate weaning strategies have been suggested to reduce stress and improve performance of calves after weaning. Two such strategies were compared with abrupt remote separation weaning in spring-born, Angus-crossbred steers. Cow-calf pairs were allotted to 3 treatments 7 d before (d−7 to 0) weaning: fence-line (FL, calves separated from dams by a fence), nose-clips (NC, placement of antisuckling device on calves which then remained with dams), or control (CTRL, calves remained with dams until d 0). All steers were transported away from their dams on d 0, placed on pasture on d 1, and maintained within weaning-method treatment groups. Behavioral observations were conducted from d−7 to−4 and d 1 to 4. The NC calves spent less time eating, more time idling, more time close to dams, walked less, and had reduced ADG compared with FL or CTRL calves before transport (P < 0.05). The CTRL calves spent less time eating, more time idling, and walked more than FL or NC calves (P < 0.05) after transport. Average daily gain of FL calves was greater than NC calves (P < 0.05). On d 0, NC calves had reduced (P < 0.05) creatine kinase and BUN concentrations and greater nonesterified fatty acid concentration. There were no treatment effects for any blood metabolite detected after transport. Nose-clip weaning did not seem to be a comparable method to FL weaning, whereas FL weaning may be an alternative to traditional weaning.

Early, abrupt weaning did not reduce risk of HIV infection or mortality in breast-fed infants of mothers with HIV

Early, abrupt weaning did not reduce risk of HIV infection or mortality in breast-fed infants of mothers with HIV

Antiretroviral Prophylaxis to Reduce Breast-Milk HIV-1 Transmission

As professionals working in a resource-limited country to prevent the transmission of the human immunodeficiency virus (HIV) from mother to child and to promote child survival and the use of highly active antiretroviral therapy (HAART) we read with interest the articles about abrupt weaning and prophylaxis regimens in infants by Kuhn et al. and Kumwenda et al. (July 10 issue).12 Harm-reduction alternatives for HIV-infected mothers who breast-feed are essential. However in the study by Kuhn et al. the risk of mother-to-child transmission or death among breast-fed infants whether they were abruptly weaned or not was more than 30%.1 Extended antiretroviral prophylaxis was superior to singledose nevirapine but 8.0% of infants were infected at birth; postnatal mother-to-child transmission related to breast-feeding added a 5.2% or 6.4% risk of infection.2 Alternatives should be considered including HAART (which is now available to HIV-infected persons in Zambia3 Malawi4 and the Dominican Republic5) formula and improved access to potable water. From 1999 to 2005 the rate of mother-to-child transmission of HIV among our patients most of whom have low levels of both income and education was 3.3% with the use of multidose antiretroviral treatment and exclusive formula-feeding; 2.8% of uninfected infants died. Pregnant women in developing countries can use HAART prophylaxis regimens for infants formula and home-purified water. The cost is significant but the savings (in lives orphan care and treating infected children) are also significant. (full-text)

Effects of Early, Abrupt Weaning on HIV-free Survival of Children in Zambia

Effects of Early, Abrupt Weaning on HIV-free Survival of Children in Zambia

Effects of Early, Abrupt Weaning on HIV-free Survival of Children in Zambia

In low-resource settings, many programs recommend that women who are infected with the human immunodeficiency virus (HIV) stop breast-feeding early. We conducted a randomized trial to evaluate whether abrupt weaning at 4 months as compared with the standard practice has a net benefit for HIV-free survival of children. We enrolled 958 HIV-infected women and their infants in Lusaka, Zambia. All the women planned to breast-feed exclusively to 4 months; 481 were randomly assigned to a counseling program that encouraged abrupt weaning at 4 months, and 477 to a program that encouraged continued breast-feeding for as long as the women chose. The primary outcome was either HIV infection or death of the child by 24 months. In the intervention group, 69.0% of the mothers stopped breast-feeding at 5 months or earlier; 68.8% of these women reported the completion of weaning in less than 2 days. In the control group, the median duration of breast-feeding was 16 months. In the overall cohort, there was no significant difference between the groups in the rate of HIV-free survival among the children; 68.4% and 64.0% survived to 24 months without HIV infection in the intervention and control groups, respectively (P=0.13). Among infants who were still being breast-fed and were not infected with HIV at 4 months, there was no significant difference between the groups in HIV-free survival at 24 months (83.9% and 80.7% in the intervention and control groups, respectively; P=0.27). Children who were infected with HIV by 4 months had a higher mortality by 24 months if they had been assigned to the intervention group than if they had been assigned to the control group (73.6% vs. 54.8%, P=0.007). Early, abrupt cessation of breast-feeding by HIV-infected women in a low-resource setting, such as Lusaka, Zambia, does not improve the rate of HIV-free survival among children born to HIV-infected mothers and is harmful to HIV-infected infants.(ClinicalTrials.gov number, NCT00310726.)

Effects of Providing Water from a Bucket or a Nipple on the Performance and Behavior of Calves Fed Ad Libitum Volumes of Acidified Milk Replacer

Little information is available on how much water ad libitum milk-fed calves consume during the milk-feeding stage and during weaning to solid feed. Further, no information exists on the effects on calf behavior and performance of different water delivery systems during these stages. Therefore, the objectives of this study were first, to examine the water intake of calves fed acidified milk replacer ad libitum during the milk-feeding and weaning stages, and second, to determine whether the method of water delivery affected water and feed intake and growth during these periods or oral behavior during weaning. To evaluate this, we registered feed and water intake, growth, and oral behaviors of 24 dairy calves before and after abrupt weaning from a 7-wk ad libitum acidified milk replacer feeding regimen. Two water sources (open bucket and nipple) were compared. During the 7-wk milk-feeding period, the calves drank, on average, 12.9±0.7 L/d of acidified milk replacer but very little water. However, after abrupt removal of milk, the 2-mo-old calves rapidly increased their water intake. Moreover, no differences in water intake between the 2 water sources were noted either before or after abrupt weaning. Calves were observed to have some difficulties in using the water nipple. Calves provided water through the nipples consumed less water at each drinking bout but visited the water nipple more frequently compared with calves provided access to water from the bucket. We observed no differences in all other behaviors observed. Overall, the calves rapidly increased their feed intake, rumination time, frequency of cross-sucking, and vocalization after weaning. In conclusion, despite the calves’ consuming very little water when provided ad libitum access to acidified milk replacer, they dramatically increased their water consumption after abrupt weaning from milk. Calves did experience some difficulties in using the water nipples.

HIV, Exclusive Breastfeeding and Weaning in Sub-Saharan Africa: Can Flash-Heating Breastmilk Help Bridge the Gap?

In wealthy countries, postnatal HIV transmission has been virtually eliminated by replacing breastfeeding with formula. But in sub-Saharan Africa, and in other resource-poor nations, where formula is exorbitantly expensive and sanitation is poor, breastfeeding causes 40% of all infant HIV infections [1]. Mothers in developing countries face a desperate dilemma: prolonged breastfeeding may transmit HIV, yet replacement feeding exposes the baby to malnutrition and infectious diseases that are often fatal. As a recent study in Botswana illustrates, even provision of replacement feeding at no cost can go wrong: after a flood contaminated water supplies used to prepare formula, nonbreastfed infants were 50-times more likely than breastfed babies to die of diarrheal disease [2]. Carefully designed trials of replacement feeding from birth (under best-case research scenarios that provided free formula and healthcare) reported that use of formula did reduce HIV transmission, but, because of the increased risk of infectious diseases in the group fed formula, longterm infant HIV-free survival was no different from infants who had been breastfed for 3–6 months [3,4]. The most encouraging news is that shortterm exclusive breastfeeding is associated with reduced HIV transmission when compared with the more common practice of mixed feeding (breastfeeding plus animal milk, other liquids or foods) [5–7]. It is hypothesized that exclusive breastfeeding defends the integrity of infant gut mucosa, making it less permeable to the HIV virus, and that women who breastfeed intensively are less likely to develop breast health problems, a known risk factor for HIV transmission [6]. However, the longer a mother breastfeeds, the higher the cumulative risk of HIV transmission [1]. A recent study estimated that more than twothirds of postnatal HIV infections transmitted through breastfeeding occurred after 6 months [5]. Hopes that rapid and early cessation of exclusive breastfeeding could reduce this risk were shattered when the problem of replacement feeding again reared its ugly head: recent studies in several different countries report dramatic increases in diarrhea, gastroenteritis, malnutrition and mortality with early weaning [8–13]. In a randomized Zambian trial, there was no difference in HIV-free survival at 24 months in the early weaning group when compared with long-term breastfeeding. Investigators noted higher viral loads in breastmilk after abrupt weaning, which could translate into higher HIV transmission if a mother decided to reinitiate lactation [14,15]. Thus, the newest recommendation from the WHO endorses the avoidance of breastfeeding only if replacement feeding is deemed acceptable, feasible, affordable, sustainable and safe. If not, they recommend exclusive breastfeeding for 6 months, followed by breastfeeding plus complementary foods to support infant growth until nutritionally adequate alternatives are available [16].

Weaning distress in dairy calves: Acute behavioural responses by limit-fed calves

Weaning typically involves both dietary and social changes as the transition from milk to solid feed is normally accompanied by reduced contact with the dam. Dairy calves provide a model to study the effect of weaning from milk independent of separation, as calves are typically separated from the cow and then fed milk artificially for several weeks before weaning. Calves likely vary in their reliance on milk, as some animals will be better established than others on solid feed before weaning. The aim of this study was to describe the immediate behavioural responses of dairy calves ( n = 30) to weaning from milk, and to compare acute responses when calves varied in consumption of solid food before weaning. To encourage the intake of solid feed some calves were fed milk diluted with water while other calves were fed non-diluted milk. Calves on diluted milk ate twice as much solid feed (calf starter) before weaning, approximately 2 kg/day. However, this treatment did not increase starter intake after weaning and did not affect the immediate behavioural response to weaning, suggesting that the acute weaning response is due to factors other than the lack of milk. To explore these other factors calves were weaned by either complete cessation of the milk-feeding routine (‘abrupt weaning’), or with continued access to the milk-feeding system but with warm water instead of milk. Calves weaned abruptly showed a stronger immediate behavioural response to weaning than did those calves provided with continued access to the milk-feeding system. The abruptly weaned calves vocalized at more than 3 times the rate, averaging more than 120 calls during the 20 min after feeding. These calves were also more active than calves with continued access to the feeding apparatus, as shown by a higher rate of movements in the pen and more time with the head outside of the pen. The reduced acute response to weaning by calves with continued access to the milk feeding system may be due to the behaviours that this system facilitates (e.g. sucking on the milk bucket), to the ingestion of the warm water, or to other rewarding attributes of the feeding system.

Milk allowance and weaning method affect the use of a computer controlled milk feeder and the development of cross-sucking in dairy calves

The effect of milk allowance and type of weaning on behaviour in dairy calves was investigated. A total of 72 calves divided into 6 blocks of 12 calves were used. The calves in each block were divided into two groups and housed in a separate section containing two straw-bedded pens, each with a computer controlled milk feeder. Within block, calves were assigned to either a low milk allowance (4.8l/day for heavy breeds and 3.6l/day for Jersey) or a high milk allowance (9.2l/day for heavy breeds and 7.2l/day for Jersey), while concentrate was feed ad libitum. One group in each block was assigned to gradual weaning from 6 to 8 weeks of age, while the other was assigned to abrupt weaning at 8 weeks of age. Recordings of cross-sucking were done on days before, during and after weaning, and use of milk and concentrate feeder was recorded throughout the experiment. Abruptly weaned calves performed more cross-sucking than gradually weaned calves immediately after weaning (P<0.01), while this difference was not found 4 days after weaning. Before weaning was initiated, calves on a low milk allowance had more unrewarded visits to the milk feeder than calves on a high milk allowance (P<0.01). During the weaning period, calves on an unchanged milk allowance had a lower number of unrewarded visits (P<0.05) to the milk feeder than gradually weaned calves. However, the first 5 days after weaning, they had longer duration (P<0.05) and a higher number of unrewarded visits (P<0.01) than gradually weaned calves. These results indicate that gradual weaning of calves reduces cross-sucking and unrewarded occupancy of the milk feeder compared to abrupt weaning. Furthermore, a high milk allowance reduces unrewarded occupancy during the milk feeding period.