Edited by: Laura Ann Boyle, Teagasc Food Research Centre, Ireland
Reviewed by: Lorenz Gygax, Humboldt University of Berlin, Germany; Maria José Hötzel, Federal University of Santa Catarina, Brazil
This article was submitted to Animal Behavior and Welfare, a section of the journal Frontiers in Veterinary Science
This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Creep feed provision may ease weaning, hence we determined the impact of providing fibrous creep feed before weaning and adding this feed to the post-weaning diet on piglet behavior and performance. Pre-weaning, litters with on average 12 piglets were given creep feed (CF,
Weaning in piglets often results in stress [reviewed by (
Weaning in commercial conditions includes multiple simultaneous stressors, including maternal separation and introduction to non-littermate piglets (social stress), relocation to unfamiliar housing (environmental stress), and a change in diet from sow's milk to solid feed (nutritional stress). Reducing the nutritional stressor at weaning may help to migitate weaning-related problems by habituating piglets to solid feed as an alternative energy source while they are with the sow (
Therefore, the present study aimed to determine the impact of fibrous creep feed provision, the impact of adding this creep feed in a small quantity to the weaner diet, and the interaction between pre-weaning creep feed provision and post-weaning creep feed supplementation on piglet behavior and performance after weaning. We hypothesized that creep feed provision would stimulate feed intake and growth of weaned piglets, and reduce haptoglobin concentrations and behaviors associated with weaning stress. We expected additional beneficial effects on the performance of weaned piglets that had access to creep feed before and, as supplement on top of the weaner diet, after weaning, as these piglets will likely experience the lowest level of food neophobia.
The Animal Care and Use committee of Wageningen University & Research (Wageningen, The Netherlands) approved the protocol of the experiment (AVD104002016515). The protocol is in accordance with the Dutch law on animal experimentation, which complies with the European Directive 2010/63/EU on the protection of animals used for scientific purposes.
Twenty-two multiparous Topigs-20 sows (range parity: 3–5) were housed and inseminated at research facility Carus (Wageningen University & Research, The Netherlands) in two consecutive batches, with
Set-up of the farrowing pen, consisting of a farrowing and free-movement area. Piglets had access to a piglet feed trough from 2 days of age, either with or without creep feed (see treatments).
A subset of 128 piglets was weaned on the same day at 4 weeks of age (29.8 ± 0.1 days of age) in two equal batches and relocated in two adjacent weaner rooms per batch in which they were housed until 6 weeks of age. At weaning, piglets were mixed with piglets within pre-weaning treatment and housed in groups of four unfamiliar piglets, of which two males and two females, in a pen of 1.80 × 2.85 m with 80% mats and 20% slatted floor. The weaner pen was equipped with a feeder (12 × 50 cm) having three feeding spaces, a drinking trough, infrared lamp and chew object, which was a metal chain with bolts. Additional chew objects were provided and replaced daily in a cycle of four objects: a squeaky ball or metal chain with two solid balls, PVC pipe or hose attached. Piglets had
Piglets were assigned to one of four treatment combinations in a 2 × 2 arrangement, with pre-weaning creep feed provision and post-weaning creep feed supplementation as experimental factors.
From 2 days of age twelve litters (
Nutrient profile of the creep feed.
Net energy | 11.8 |
Dry matter | 891 |
Starch | 290 |
Non-starch polysaccharides |
261 |
Crude protein | 195 |
Crude fat | 61 |
Crude fiber | 44 |
Crude ash | 57 |
Calcium | 9.1 |
Phosphorus | 6.1 |
Sodium | 2.2 |
Standardized ileal digestible lysine | 11.9 |
Standardized ileal digestible methionine | 4.8 |
Standardized ileal digestible threonine | 7.1 |
Standardized ileal digestible tryptophan | 2.4 |
Ingredient composition of the creep feed.
Wheat | 21.9 |
Barley | 15 |
Maize | 15 |
Soy protein concentrate | 7 |
Soybeans (heat treated) | 5 |
Galacto-oligosaccharides | 5 |
Potato protein | 4 |
Sugarbeet pulp (dehydrated) | 4 |
Oat hulls | 4 |
Inulin | 4 |
High-amylose starch (± 75% amylose) | 4 |
Soybean oil | 3 |
Blood meal (spray dried) | 2 |
Dicalcium phosphate | 1.7 |
Sucrose | 1.5 |
Calcium carbonate | 1.0 |
Sodium chloride | 0.5 |
Premix |
0.5 |
Potassium bicarbonate | 0.3 |
L-lysine hydrochloride | 0.3 |
DL-methionine | 0.2 |
L-threonine | 0.04 |
L-tryptophan | 0.04 |
Total | 100 |
Distribution of sows over the farrowing rooms was balanced for sow body weight and back fat at 1 week before farrowing. At 1 week before farrowing, sows were initially allocated to the treatment groups in such a way that the average parity was the same for both treatments. There were a few extra sows (reserves) and at the start of the experiment at d2 some of the sows and their litters were excluded due to antibiotic treatment of the sow or a low litter size (<9 piglets alive per litter at d2). As it could not be anticipated beforehand which sows would be excluded from the experiment, distribution of treatment groups over the farrowing rooms was not perfectly balanced in batch 2 (4:2 distribution per room). Within the farrowing rooms, there were 2 blocks of 4 adjacent pens, with each block consisting of the two treatment groups. The first and last pen of the rooms were kept empty whenever possible (
After weaning, effects of creep feed provision before weaning and creep feed supplementation after weaning were studied in a 2 × 2 arrangement. Thus, 16 pens of which 8 with CF- and 8 with NF-piglets had
Piglets were selected based on their sex and their BW at one day before weaning (CF-CON: 8.35 ± 0.09 and CF-CS: 8.34 ± 0.09 vs. NF-CON: 7.91 ± 0.11 kg and NF-CS: 7.91 ± 0.07 for selected piglets), which was close to the average weight of the litter and treatment group (CF: 8.27 ± 0.20 vs. NF: 7.85 ± 0.31 for all suckling piglets). The selected piglets originated from ten litters per treatment group (from 10 out of 12 CF-litters and 10 out of 10 NF-litters to keep genetic variation the same between treatments). As the number of NF-litters was lower in batch 1 (
A timeline of all measurements is provided in
Piglets were individually weighed on d2 (fixed to birth date, thereafter all measurements were performed on the same day for all piglets), 15, 21, 29 after birth and d2, 5, 9 and 14 post-weaning. Creep feed intake was determined per CF-litter between d2-15, 15-21, and 21-30 after birth. Post-weaning feed intake was determined per pen between d0-2, 2-5, 5-9, and 9-14 after weaning. The intake per feed type (weaner feed or creep feed supplement) was also determined. If any, feed remains on the floor were collected. Feed wastage was kept to a minimum by placing the feeders on the solid floor in the farrowing and weaner pens. Fecal consistency scores of fecal droppings in the pens were taken daily by one observer for the first 14 days post-weaning according to the fecal classification scale with four categories of Pedersen and Toft (
Piglets were individually numbered using dark permanent hair dye (pre-weaning) or animal marking spray (post-weaning) to allow individual recognition during behavioral observations. Live behavioral observations were done on all piglets in the farrowing rooms at d11, 16, 22 and 27 after birth using 4.5-min instantaneous scan sampling for six sessions of 63 min/d, i.e., 84 scans/piglet/d. Observation sessions started at 8:15, 9:30, 10:45, 13:45, 15:00, and 16:45 h. Behavior in the weaner rooms was observed at d6 and 13 post-weaning using 2-min instantaneous scan sampling for six sessions of 1h/d, i.e., 180 scans/piglet/d, starting at 8:00, 9:15, 10:30, 14:00, 15:15, and 16:30 h. Behaviors were scored using a Psion hand-held computer with the Pocket Observer 3.1 software package (Noldus Information Technology, Wageningen, The Netherlands) or using a pen and scoring sheets. The ethograms are given in
Haptoglobin was determined at d29 after birth in 21 CF- and 20 NF-piglets. In 28 of these piglets additional samples were taken before weaning at d2 and 15 after birth (1-2 pigs per litter,
Piglet behaviors in the farrowing room at d11, 16, 22 and 27 after birth were averaged per piglet per day (84 scans) and expressed as proportions of time. Based on the observations in the farrowing rooms we also discriminated “eaters,” i.e., piglets scored eating creep feed from the feed trough or floor at least once, from “non-eaters” per observation day. Piglet behaviors in the weaner room at d6 and 13 after weaning were averaged per piglet per day (180 scans) and expressed as proportions of time.
Weighing piglets at d2 and the provision of creep feed at d2 were fixed to the birth date of the litter, thereafter all measurements were performed on the same day for all piglets. Growth and creep feed intake between d2-15 before weaning consisted of a different number of days per litter as result of the variation in birth date. This was accounted for by calculating average daily gain and average daily creep feed intake. Three of the selected male weaner piglets, i.e., 1 CF-CON and 2 NF-CON piglets, were excluded from haptoglobin analyses due to health issues, as haptoglobin increases with acute infection and inflammation.
Data were analyzed using the statistical software SAS 9.4 (SAS Institute Inc., Cary, NC, USA). An overview of data analysis, i.e., the statistical models used for the different response parameters, can be found in
Before weaning, average daily creep feed intake (after log transformation) was analyzed in a general linear mixed model with a spatial power covariance structure, a random effect of litter, and fixed main effects of batch (1 vs. 2) and period (d2-15, d15-21, d21-30). The effect of (observation) day on the binary variable “eater” (1=eater, 0=non-eater) was analyzed in a generalized linear mixed model with a binary distribution and logit link function that, apart from a fixed effect of batch and day (d11, d16, d22, d27) and a random effect of litter, also included a random effect of litter nested within day (split-plot) to account for dependence between littermates within a day. To illustrate the increase in “eaters” over time we calculated and reported the percentage of eaters by dividing the number of eaters per litter by the total number of piglets in the same litter at that observation day. Piglet average daily gain (ADG) and BW were analyzed in a general linear mixed model with fixed main effects of batch and creep feed provision (CF vs. NF), a random effect of litter, and litter size as covariate. Uniformity in BW expressed as coefficient of variation (CV) was analyzed in a general linear model with fixed main effects of batch and creep feed provision. Behavior in the farrowing pen was analyzed in a generalized linear mixed model with a binomial distribution, logit link function and an additional multiplicative over-dispersion parameter. The model included fixed effects of batch, and fixed effects and interactions of creep feed provision and day. In addition, the model included a random effect of litter and random effect of litter nested within day (split-plot).
After weaning, piglet ADG and BW were analyzed in a general linear mixed model with fixed effects of batch, and main effects and interactions of pre-weaning creep feed provision (CF vs. NF) and post-weaning creep feed supplementation (CS vs. CON). Moreover, the model included a random effect of weaner pen and litter. Average daily feed intake (ADFI), uniformity in BW expressed as CV, feed conversion ratio (FCR) and mean FCS were analyzed in a general linear model on pen level with the same fixed effects as for post-weaning ADG and BW. CV in BW at one day before weaning was used as covariate in the analyses of CV in BW at 14 days post-weaning. For ADFI data between d0-2 post-weaning no batch effect was included as it was recorded in batch 2 only as result of technical difficulties in batch 1. Average daily intake of the creep feed supplement within CS was analyzed in a general linear model with fixed effects of batch and creep feed provision. The duration of diarrhea (score 3 + 4) was analyzed in a generalized linear model using a Poisson distribution, log link function and an additional multiplicative over-dispersion parameter with the same fixed main effects as used for mean FCS. Behavior in the weaner pen was analyzed in a generalized linear mixed model using a binomial distribution, logit link function and an additional multiplicative overdispersion parameter. The model included the same fixed effects and random effects as mentioned for post-weaning ADG and BW.
Haptoglobin concentrations were analyzed after log transformation in a general linear mixed model with a spatial power covariance structure and a random effect of piglet. The model had fixed main effects of pre-weaning creep feed provision, day, their interactions, as well as batch.
Fixed effects with
In CF-litters, creep feed intake increased with age [
The percentage of eaters per CF-litter, based on the behavioral observation of eating at least once during scan sampling, increased with age [
ADG of CF-piglets throughout lactation (d2-29) was higher than that of NF-piglets (
Pre-weaning growth before weaning
CF-piglets spent 2.9 ± 0.5% of their time either exploring or eating the feed, which were behaviors the NF-piglets could not perform. Time spent on other behaviors in the farrowing room (sucking and massaging udder, drinking, exploring environment, inactive behavior, playing and manipulating pen mates or the sow) were unaffected by providing creep feed (
Effects of creep feed provision from 2 days of age on piglet behavior before weaning (d11, 16, 22 and 27 of age).
Suckling and massaging udder | 15.6 ± 1.2 | 13.6 ± 0.7 | 0.76, 0.40 | 7.30, |
2.41, 0.08 |
Drinking | 0.3 ± 0.1 | 0.3 ± 0.1 | 0.29, 0.60 | 3.20, |
0.14, 0.93 |
Eating feed | - | 2.6 ± 0.5 | - | - | - |
Exploring feed | - | 0.3 ± 0.04 | - | - | - |
Exploring environment | 14.4 ± 0.8 | 12.8 ± 1.0 | 0.91, 0.35 | 46.61, |
1.22, 0.31 |
Inactive behavior | 54.1 ± 1.8 | 55.3 ± 2.1 | 0.05, 0.83 | 6.22, |
1.21, 0.31 |
Playing | 2.1 ± 0.2 | 2.3 ± 0.2 | 0.07, 0.80 | 1.19, 0.32 | 0.17, 0.92 |
Manipulating pen mates | 1.0 ± 0.1 | 0.9 ± 0.07 | 0.04, 0.85 | 0.48, 0.70 | 0.07, 0.97 |
Manipulating sow | 0.6 ± 0.08 | 0.4 ± 0.05 | 2.09, 0.16 | 3.57, |
0.31, 0.82 |
No main effects of pre-weaning creep feed provision, post-weaning creep feed supplementation and their interaction were observed on feed intake or growth during the first two days after weaning (
Post-weaning piglet performance of piglets that were provided with creep feed from 2 days of age (CF) or not (NF) before weaning and provided with a weaner diet (CON,
ADFI, g/pig/d | |||||||
d 0–2 |
182 ± 20 | 169 ± 11 | 127 ± 16 | 150 ± 26 | 4.17, 0.06 | 0.04, 0.84 | 1.03, 0.33 |
d 2–5 | 313 ± 16 | 279 ± 17 | 380 ± 23 | 352 ± 21 | 12.83, |
2.54, 0.12 | 0.03, 0.88 |
d 5–9 | 389 ± 13 | 347 ±13 | 390 ± 24 | 396 ± 20 | 1.82, 0.19 | 0.97, 0.33 | 1.62, 0.21 |
d 9–14 | 575 ± 22 | 636 ± 18 | 519 ± 23 | 582 ± 30 | 5.71, |
7.26, |
0.00, 0.97 |
d 2–14 | 447 ± 6 | 450 ± 10 | 441 ± 8 | 462 ± 9 | 0.11, 0.75 | 2.03, 0.17 | 1.12, 0.30 |
ADG, g/pig/d | |||||||
d−1–2 | 218 ± 19 | 175 ± 19 | 167 ± 21 | 203 ± 21 | 0.25, 0.62 | 0.01, 0.94 | 3.23, 0.08 |
d 2–5 | 236 ± 24 | 259 ± 19 | 315 ± 31 | 310 ± 24 | 6.49, |
0.14, 0.72 | 0.33, 0.57 |
d 5–9 | 356 ± 21 | 339 ± 16 | 303 ± 22 | 336 ± 23 | 0.50, 0.49 | 0.14, 0.71 | 0.90, 0.35 |
d 9–14 | 488 ± 25 | 484 ± 21 | 547 ± 28 | 532 ± 19 | 1.93, 0.18 | 0.20, 0.65 | 0.30, 0.59 |
d−1–14 | 348 ± 13 | 339 ± 10 | 359 ± 21 | 369 ± 12 | 0.79, 0.38 | 0.00, 0.96 | 0.11, 0.74 |
FCR, d 2–14 | 1.12 ± 0.08 | 1.15 ± 0.05 | 1.14 ± 0.06 | 1.22 ± 0.03 | 0.75, 0.39 | 0.83, 0.37 | 0.15, 0.70 |
Mean FCS |
0.31 ± 0.06 | 0.42 ± 0.06 | 0.31 ± 0.06 | 0.34 ± 0.07 | 0.41, 0.53 | 1.13, 0.30 | 0.41, 0.53 |
No. of days with diarrhea | 4.38 ± 0.78 | 5.25 ± 0.56 | 4.13 ± 0.85 | 4.25 ± 0.98 | 0.54, 0.47 | 0.33, 0.57 | 0.17, 0.68 |
BW and BW variability (coefficient of variation in BW) at 14 days after weaning of piglets that were provided with creep feed from 2 days of age (CF) or not (NF) before weaning and provided with a weaner diet (CON,
Within CS, the creep feed supplement was consumed in greater amounts by NF- than CF-piglets throughout the first two weeks post-weaning (d0-14, NF-CS: 40 ± 0.5 vs. CF-CS: 33 ± 2.0 g/pig/d,
Diarrhea was first observed in the pens at d2 post-weaning and peaked at d6 post-weaning when half of the pens contained diarrheic fecal pools. Thereafter, diarrhea partially recovered but remained present and peaked for a second time at the end of the experiment at d14 post-weaning. Diarrheic fecal pools of score 3 were highly prevalent (97% of the pens), whereas pools of score 4 were less prevalent (25% of the pens). The prevalence of watery diarrhea in the first 2 weeks post-weaning (% of pens with ≥ 1 day watery diarrhea) was 25, 37.5, 0, and 37.5% for CF-CON, CF-CS, NF-CON, and NF-CS, respectively. The severity and duration of diarrhea observed in the first two weeks post-weaning did not differ between the treatment groups (
CS-piglets spent more time on exploring feed than CON-piglets at wk 2 post-weaning (CS: 0.29 ± 0.08 vs. CON: 0.11 ± 0.03%,
Behavioral activities (% of total observations) in the first 2 weeks after weaning (week 1: 36 days of age, week 2: 44 days of age).
Drinking | 1.0 ± 0.2 | 1.0 ± 0.1 | 1.2 ± 0.1 | 1.1 ± 0.2 | 0.01, 0.94 | 0.58, 0.45 | 0.09, 0.77 |
Eating feed | 11.6 ± 0.7 | 12.7 ± 1.1 | 10.4 ± 0.9 | 11.0 ± 1.1 | 2.30, 0.14 | 0.70, 0.41 | 0.05, 0.83 |
Exploring feed | 0.07 ± 0.03 | 0.23 ± 0.10 | 0.07 ± 0.03 | 0.31 ± 0.11 | 0.00, 0.96 | 3.18, 0.09 | 0.75, 0.39 |
Exploring environment | 22.8 ± 2.4 | 23.8 ± 2.7 | 24.0 ± 1.0 | 21.8 ± 1.4 | 0.01, 0.91 | 0.12, 0.73 | 0.65, 0.43 |
Inactive behavior | 46.8 ± 3.1 | 47.3 ± 3.7 | 47.4 ± 2.4 | 50.6 ± 3.4 | 0.52, 0.48 | 0.46, 0.50 | 0.31, 0.58 |
Playing | 3.2 ± 0.6 | 2.9 ± 0.6 | 3.3 ± 0.4 | 2.3 ± 0.3 | 0.05, 0.82 | 2.11, 0.16 | 0.48, 0.49 |
Manipulating pen mates | 1.3 ± 0.3 | 1.3 ± 0.3 | 1.3 ± 0.4 | 1.0 ± 0.3 | 0.09, 0.77 | 0.60, 0.45 | 1.05, 0.31 |
Drinking | 1.2 ± 0.1 | 1.2 ± 0.2 | 1.4 ± 0.2 | 1.3 ± 0.2 | 0.93, 0.34 | 0.03, 0.86 | 0.00, 0.98 |
Eating feed | 10.4 ± 1.1 | 10.5 ± 0.7 | 10.9 ± 1.0 | 11.5 ± 0.6 | 0.64, 0.43 | 0.15, 0.70 | 0.09, 0.76 |
Exploring feed | 0.07 ± 0.03 | 0.31 ± 0.14 | 0.16 ± 0.05 | 0.26 ± 0.08 | 0.81, 0.38 | 5.27, |
1.02, 0.32 |
Exploring environment | 33.4 ± 1.5 | 28.4 ± 3.0 | 29.5 ± 1.9 | 26.8 ±1.7 | 1.57, 0.22 | 3.43, 0.07 | 0.28, 0.60 |
Inactive behavior | 39.9 ± 1.9 | 45.7 ± 3.4 | 43.0 ± 2.7 | 45.5 ± 2.5 | 0.27, 0.61 | 2.36, 0.14 | 0.37, 0.55 |
Playing | 2.8 ± 0.5 | 2.7 ± 0.4 | 3.2 ± 0.4 | 2.5 ± 0.4 | 0.02, 0.88 | 0.71, 0.41 | 0.58, 0.45 |
Manipulating pen mates | 1.7 ± 0.5 | 1.7 ± 0.7 | 1.8 ± 0.5 | 1.9 ± 0.4 | 0.45, 0.51 | 0.02, 0.90 | 0.04, 0.85 |
There was no difference in absolute haptoglobin concentrations between NF- and CF-piglets for any of the time points measured (
Plasma haptoglobin concentrations of piglets that were provided with creep feed from 2 days of age (CF) or not (NF) before weaning and provided with a weaner diet after weaning. PRE = creep feed yes/no pre-weaning. Haptoglobin was determined at d29 after birth in 21 CF- and 20 NF-piglets. In 28 of these piglets additional samples were taken before weaning (
The present study was performed to determine the impact of pre-weaning creep feed provision, post-weaning creep feed supplementation and their interaction on piglet behavior and performance after weaning. We hypothesized that piglets with access to the creep feed both before weaning and as a supplement after weaning would experience the lowest level of food neophobia compared to the other treatment groups and therefore ingest the largest amount of feed and perform the best in the first days after weaning. The results of this study did not confirm this hypothesis. Effects of pre-weaning creep feed provision and post-weaning creep feed supplementation will be discussed separately below.
Given that piglets provided with creep feed would be more familiarized with solid feed before weaning, we anticipated them to display increased feed intake after weaning. As a result, we hypothesized that creep feed provision would stimulate growth of weaned piglets, and reduce haptoglobin concentrations and weaning-stress-associated behaviors. However, this study did not support this hypothesis. There may be several reasons for this lack of an effect of creep feed provision. Firstly, the housing conditions of the piglets in this study may have been more favorable in terms of behavioral needs compared to commercial farming, as the density of piglets per pen and the number of piglets that shared one chew object simultaneously (2 piglets/chew object) were considerably lower. Hence, when kept in commercial farming conditions, behaviors like chewing and rooting the environment may become more re-directed at pen mates compared to our experiment, where the chewing behavior mainly targeted the environment and chew objects in it. Secondly, stress from removal of the sow (social stress), mixing with unfamiliar piglets (social stress) and housing in a novel pen (environmental stress), may have overruled the stress from the abrupt change in diet (nutritional stress). Hötzel et al. (
We did not observe differences in overall ADFI, ADG and FCR in the first two weeks post-weaning, or in BW at 14 days post-weaning, between NF- and CF-piglets in line with findings of others (
The creep feed supplement was consumed in greater amounts by NF- than CF-piglets after weaning, while we expected the opposite due to reduced neophobia of CF-piglets toward this feed. We think a novelty effect would not be the sole explanation, as the effect lasted for the first two weeks after weaning. The larger pellet sizes in the creep feed supplement may facilitate handling of the pellets by NF-piglets (
We predicted post-weaning supplementation of creep feed to increase feed exploration and intake and to reduce weaning-stress-induced behaviors in the weaner pen by reducing food neophobia of piglets that were given creep feed before weaning. Indeed, creep feed supplementation after weaning increased the time spent on exploratory behavior toward the feed, both in CF- and in NF-piglets at week 2 post-weaning. This might be the result of dietary variety established by the two feeds provided [as suggested by (
Post-weaning creep feed supplementation thus showed positive effects on feed exploration and intake in the second week after weaning, although the creep feed was only provided in a limited amount on top of the weaner diet. This might have been the result of dietary variety established by the two feeds (
Results of the present study indicate that providing piglets fibrous creep feed before weaning and as a supplement on top of their weaner diet after weaning had no clear effects on piglet behavior and performance. The results therefore do not support that creep feed provision may reduce the nutritional stressor at weaning.
All datasets generated for this study are included in the article/
The animal study was reviewed and approved by the Animal Care and Use committee of Wageningen University & Research (Wageningen, The Netherlands).
All authors designed the experiment. AM and RC conducted the experiment. AM analyzed the data, wrote the manuscript and prepared the figures. JB advised on data analyses. RC, WG, BK, MK, and JB substantively revised the manuscript. All authors approved the submitted version.
The study was co-financed by Cargill Animal Nutrition and Coppens Diervoeding. The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
The authors thank the research assistants and students of the Adaptation Physiology Group (Wageningen University & Research) for their help with the experiment and laboratory analyses. We also like the acknowledge personnel and trainees of the animal research facilities in Wageningen (Carus) for taking care of the animals and for their technical assistance. The authors are grateful to Tamme Zandstra for producing the creep feed and to FrieslandCampina Ingredients for providing Vivinal GOS.
The Supplementary Material for this article can be found online at: