Effect of creep feed consumption on individual feed intake characteristics and performance of group-housed weanling pigs 1,2

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1 Effect of creep feed consumption on individual feed intake characteristics and performance of group-housed weanling pigs 1,2 E. M. A. M. Bruininx* 3, G. P. Binnendijk*, C. M. C. van der Peet-Schwering*, J. W. Schrama, L. A. den Hartog, H. Everts, and A. C. Beynen *Research Institute for Animal Husbandry, 8203 AD Lelystad, The Netherlands; Wageningen Institute of Animal Sciences, Wageningen University, 6700 AH Wageningen, The Netherlands; Nutreco Agriculture R&D, 5830 AE Boxmeer, The Netherlands; and Utrecht University, Faculty of Veterinary Medicine, Department of Nutrition, 3508 TD Utrecht, The Netherlands ABSTRACT: To assess the effects of creep feed consumption on individual feed intake characteristics and performance of group-housed weaned pigs, 16 litters (149 piglets) were fed a commercial creep feed (3,040 kcal NE/kg, 15.2 g lysine/kg) supplemented with 1% chromic oxide. Another five litters (48 piglets) were not given access to creep feed (no-feed). Piglets were weaned at 28 d after birth. On d 18, 22, and 27 of age, fecal samples from all the piglets were taken using fecal loops. A green color of the feces indicated that the piglet had eaten creep feed. Piglets that had green-colored feces three times were considered as eaters. Piglets that never showed green-colored feces were considered as non-eaters. At weaning 22 piglets of each type (no-feed, non-eaters, and eaters) were selected based on BW, litter origin, and sex. These 66 pigs were assigned to six pens equipped with computerized feeding stations. Eaters, non-eaters, and no-feed pigs were equally divided over all six pens. After weaning a prestarter (d 0 to 13) and a starter diet (d 14 to 34) were offered for ad libitum consumption. The individual feed intake characteristics of latency time (interval between weaning and first feed intake) and initial feed intake (intake during the first 24 h following first feed intake) and performance traits were determined for all piglets. The pigs that were designated as eaters needed less time between weaning and first feed intake than the pigs that were designated as non-eaters and no-feed pigs (P = 0.04 and P = 0.06, respectively). Initial feed intake was not affected (P > 0.1) by feed intake prior to weaning. However, during d0to8theeaters had more visits per day during which feed was consumed than both the non-eaters and no-feed pigs. Averaged over the first 8 d after weaning, the ADFI and ADG of the eaters were higher than that of the non-eaters and no-feed pigs (P < 0.05). Averaged over the total 34-d period the effect of creep feed intake on postweaning ADFI was much less pronounced (P = 0.20), whereas ADG of the eaters was the highest (P < 0.05). Creep feed intake during the sucking period stimulates early postweaning feed intake as well as postweaning performance. Key Words: Creed Feed, Feed Intake, Pigs, Weaning 2002 American Society of Animal Science. All rights reserved. J. Anim. Sci : Introduction Early and high postweaning feed intakes are considered to prevent postweaning health problems and to stimulate performance of the weaned pig (Makkink, 1993; McCracken et al., 1995; Pluske et al., 1996). To ease the transition from milk during the suckling period 1 The authors thank H. J. A. Diepstraten for biotechnical assistance. 2 A portion of this work was presented in abstract form at the 2001 Annu. Mtg. of the British Society of Animal Science. 3 Correspondence: P.O. Box 2176 (phone: ; fax: ; e.m.a.m.bruininx@pv.agro.nl). Received October 22, Accepted December 21, to solid feed after weaning, piglets frequently are given a highly palatable and easily digestible diet while they are still nursing (creep feeding). However, evidence for the assumed benefit of creep feeding is scarce (Fraser et al., 1994). Studies on the postweaning effects of creep feeding use whole-litter values for preweaning feed intake. This implies averages for the highly variable intakes of individual littermates (Pajor et al., 1991). Adding chromic oxide to the creep feed, Barnett et al. (1989) were able to discern piglets that had ingested creep feed (green feces) from noneating piglets. However, the piglets were mixed at weaning and then feed intake was measured on a pen level. This might explain the absence of an effect of creep feed intake on postweaning performance (Barnett et al., 1989). Using feeding stations, Bruininx et al. (2001a) showed that the 1413

2 1414 variation in feed intake after weaning is also considerable among individual pigs. Information on individual pre- and postweaning feed intake combined could provide more insight into the relationship between preweaning feed intake and postweaning performance. Therefore, the objective of the present study was to assess whether creep feed consumption before weaning stimulates the development of postweaning feed intake and performance of individual weaned pigs housed in groups. Preweaning Materials and Methods Animals and Design. In the experiment 21 litters (198 piglets) originating from Dutch Landrace, Finnish Landrace, and Great Yorkshire rotational-bred sows and Great Yorkshire terminal boars were used. Based on litter size and sow parity, 16 litters (149 piglets) were offered free access to a commercial creep feed diet (13.7 g/kg apparently ileal digestible lysine and 3,040 Kcal/kg NE) containing 1.0% chromic oxide. The remaining five litters (49 piglets) were offered no creep feed. From 11 d of age until weaning at a mean age of 28 d, creep feed was provided in plastic creep feeders (MS Agripan, Schippers, Bladel, The Netherlands) that could be fixed on the slats in the farrowing pens. To avoid spillage of creep feed, these creep feeders were partitioned. During the suckling period piglets were housed with their dam in conventional farrowing crates. The farrowing rooms were maintained at 20 C in combination with floor heating at 30 C. All piglets received an intramuscular Fe injection (200 mg Fe, Fe Dextran, AUV Cuijk) on d 2 after birth. Each piglet was individually identified by a number tattooed in the right ear. All piglets had unlimited access to water via nipple drinkers. On 18, 20, 22, 25, and 28 d after birth, feed intake per litter was determined by collecting and weighing the remaining feed. On d 18, 22, and 27 after birth fecal samples from all piglets were taken using fecal loops. The color of each sample was immediately visually determined. A green color of the feces indicated that the pig had eaten creep feed (Barnett et al., 1989). Piglets that showed green-colored feces at all three sampling moments were designated as eaters. Piglets that never showed greencolored feces were designated as non-eaters. Additionally, piglets that had not been offered creep feed were designated as no-feed pigs. From the 149 creep-fed piglets, 26 piglets (11 litters) showed green feces on all three sampling days, whereas 28 creep-fed piglets (12 litters) never showed green feces. From the remaining 95 creep-fed piglets (16 litters), 55 showed green feces once (25 piglets) or twice (30 piglets). The feces of the remaining 40 piglets was at least once considered to be impossible to judge due to indistinguishable colors. Bruininx et al. Postweaning Experimental Design. Based on BW, litter, and sex 22 eaters (16 gilts and 6 boars), 22 non-eaters (8 gilts and 14 boars), and 22 no-feed piglets (8 gilts and 14 boars) were selected at weaning. Due to a limited availability of piglets for each treatment group, the numbers of boars and gilts per treatment were disproportionate. Considering litter origin and sex, the pigs of the three treatments were equally divided across the six pens. On the day of weaning, sows were removed from the piglets at approximately Weaning and transferring the pigs to the nursery rooms was completed at approximately Pigs were weighed at weaning (d 0) and 4, 8, 13, and 34 d thereafter. The care and treatment of the pigs were according to Dutch animal welfare legislation. Housing and Feeding. After weaning, all 66 pigs were housed in six pens (11 pigs per pen) of 2.65 m 1.5 m. The pens had fully slatted floors consisting of 1.8-m plastic slats and 0.85-m metal tri-bar slats. The pens were situated in a room with computer-controlled heating and mechanical ventilation systems. The room was illuminated with artificial light from 0700 to All pens were equipped with IVOG-feeding stations (individual voluntary feed intake in group housing; Insentec B.V., Marknesse, The Netherlands) for weanling pigs (Bruininx et al., 2001b). These feeding stations recorded feeder weight and time at the beginning and end of each visit to the feeder together with the electronic identification number of the pigs that was given by an ear tag. Feed intake data were screened before calculations of feed intake characteristics. Screening was based on the recorded feed intake per visit (g) and the calculated feeding rate per visit (g/min) according to the method of Bruininx et al. (2001a). Pigs were given free access to feed and water during the entire postweaning period. Water was supplied via nipple drinkers. During the first 13 d (Phase 1), a pelleted prestarter diet (Table 1) was provided that was replaced over a 3- d period by a pelleted starter diet (Table 1) for the last 21 d of the nursery period (Phase 2). Pigs were fed commercial diets without antibiotics, organic acids, and pharmacological levels of copper and zinc. During the 3-d switch-over period a mixture of the prestarter and starter diets was given, the ratios being 2:1, 1:1, and 1:2 on the three subsequent days. Feed Intake Characteristics. The development of feed intake of individual pigs during the first days after weaning was computed using the method of Bruininx et al. (2001a). Three variables were computed: the interval (h) between weaning and first feed intake (latency time), the amount of feed consumed during the first 24 h after the first recorded feed intake (initial feed intake, g/kg 0.75 BW), and the daily increase in feed intake (g/ kg 0.75 BW daily). The latter variable represents the amount of feed consumed between the day after the first recorded feed intake and the day that the energy intake met or exceeded 1.5 times the maintenance en-

3 Pre- and postweaning feed intake of pigs 1415 Table 1. Composition of pelleted diets (as fed) Item Prestarter diet Starter diet Ingredients, % Barley Wheat Corn Whey powder Extracted soybeans Toasted soybeans Extracted sunflower seed 3.70 Linseed expeller Fish meal Fat a Limestone Monocalcium phosphate Beet molasses Salt Phytase premix (1000 phytase units/kg) L-Lysine DL-Methionine L-Threonine L-Tryptophan Vitamin and mineral premix b Chemical analysis, % Dry matter Crude protein Crude fat Crude fiber Ash Zinc, mg/kg Copper, mg/kg Net energy, kcal/kg c a Mixture of 25% animal fat and 75% vegetable oil. b Provided the following nutrients per kilogram of prestarter and starter diet: retinol, 12,000 IU; cholecalciferol, 1,800 IU; folic acid, 0.3 mg; cyanocobalamin, 17.5 g; pantothenic acid, 10 mg; α-tocopherol, 30 IU; biotin, 0.05 mg; menadione dimethyl-pyrimidinol, 0.5 mg; niacin, 20 mg; riboflavin, 3.5 mg; choline, 0.5 g; pyridoxine, 1.5 mg; thiamine, 1 mg; cobalt, 0.15 mg (as CoSO 4 7H 2 O); copper, 15 mg (as CuSO 4 5H 2 O); manganese, 25 mg (as MnO 2 ); iron, 100 mg (as Fe SO 4 7H 2 O); zinc, 65 mg (as ZnSO 4 ); iodine, 0.45 mg (as KI); selenium, 0.25 mg (as Na 2 SeO 3 5H 2 O). c Calculated with the use of the Dutch feed tables (CVB, 2000). ergy requirement (1.5 times 131 kcal ME/kg 0.75 BW daily) according to Le Dividich and Herpin (1994). For the calculation of metabolic BW on a day that BW was not measured, a linear relationship in BW between the two adjacent weighing days was assumed. Statistical Analyses. Average daily feed intake, ADG, gain:feed ratios, initial feed intake, and the daily increase in feed intake were evaluated by analysis of variance using the GLM procedures of SAS (SAS Inst. Inc., Cary, NC). The model used was Y ijk = + P i + G j + C k + G C + e ijk where Y ijk = a specific trait per period per pig; = overall mean; P i = fixed effect of pen i (i = 1 to 6); G j = fixed effect of sex (j = 1,2); C k = fixed effect of creep feed consumption (k = 1, 2, 3); and e ijk = error term. Pairwise differences between treatment means were assessed using a t-test. In accordance with our earlier results (Bruininx et al., 2001a), preliminary analysis showed that all data except the time between the start of the experiment and first feed intake (latency time) followed a normal distribution. Therefore, survival like Kaplan-Meier curves (Kalbfleisch and Prentice, 1980) were constructed for latency time as affected by creep feed consumption (eaters vs non-eaters vs no-feed). Results and Discussion Creep Feed Intake. Total creep feed consumption ranged from 445 to 7,840 g per litter. Averaged over the 149 creep-fed piglets, feed intake from d 11 to d 28 after birth was 377 g per piglet (SD = g; Figure 1). This average creep feed intake was similar to the 385 g per piglet fed a highly digestible, complex diet (Fraser et al., 1994) but considerably higher than the mean intake of 77 g per piglet on a simple corn-soybean diet (Barnett et al., 1989). Additionally, in the present study about 60% of the total creep feed intake was realized during the last 6 d before weaning, whereas this was about 80% during the last week before weaning (28 d of age) in the study of Fraser et al. (1994).

4 1416 Bruininx et al. Figure 1. Average cumulative creep feed consumption (g/piglet + SD) per period during nursing. Chromic oxide was added as a marker to the creep feed. The color of the fecal samples was evaluated three times (d 18, 22, and 27) for the presence of chromic oxide. This allowed us to discern eating piglets from non-eating piglets (Barnett et al., 1989). In order to select piglets that consumed a substantial amount of creep feed, only piglets that had green-colored feces at all three sampling moments were considered as eaters. Previously, Appleby et al. (1991) suggested that, within litters, individual piglets that eat more than their littermates on one day usually do so on other days. Despite this suggested consistency in creep feed intake, the presence of chromic oxide at all three sampling moments does not ensure that a piglet continued eating throughout the course of the experiment. Furthermore, some piglets may have consumed very small amounts of creep feed together with a considerable amount of milk, which may have masked the green color indicative of creep feed intake (Barnett et al., 1989). Our results confirm that preweaning feed consumption is highly variable between and within litters. Although there clearly are some disadvantages to the use of chromic oxide as a qualitative indicator of individual creep feed consumption, it can be considered as a useful tool to obtain information on variability of creep feed consumption within and among litters under practical husbandry conditions. Effects of Creep Feed Consumption on Early Postweaning Feed Intake Characteristics and Performance. The pattern of the survival like, Kaplan-Meier curves (Kalbfleisch and Prentice, 1980) for the interval (h) between the start of the experiment and first feed intake were affected by creep feed consumption (P = 0.06; Figure 2). The number of pigs that were designated as eaters during the suckling period but that did not eat after weaning decreased faster than that of the pigs designated as non-eaters and no-feed pigs (P = 0.04 and P = 0.06, respectively). The patterns of the non-eaters and no-feed pigs did not differ (P > 0.10). These differences indicate that preweaning feed consumption stimulates Figure 2. Percentage of weanling pigs that had not eaten after weaning as a function of postweaning interval (mean = 10.7 h; SD = 1.73 h). Curves are given for eaters ( ), non-eaters ( ) and no-feed pigs (- ---)pigs. Eaters and non-eaters were given access to a chromic oxide containing creep feed from d 11 after birth until weaning (d 28). A green color of the feces due to the presence of chromic oxide indicated that a pig had eaten creep feed. Piglets that had green feces at all three sampling moments were designated as eaters. Piglets that never had green feces were designated as non-eaters. The dark periods are indicated by shaded bars. the onset of feeding after weaning. Fifty percent of the piglets designated as eaters during the suckling period started eating within 4 h after the start of the experiment, whereas the non-eaters and no-feed piglets needed about 6.7 and 6.9 h, respectively. Previously, Bruininx et al. (2001a) found that about 50% of all noncreep-fed pigs started eating within 4 h, which is about 2.9 h later than the no-feed piglets in the present study. This 2.9-h difference may be related to the about 3-h shorter period between removal of the sows (0900 for both experiments) and the start of the present experiment (1200) compared with our previous experiment (1500). During this period, the pigs had no access to feed. The longer period of starvation in our previous study may have stimulated the pigs in their search for food, resulting in a shorter latency time. The number of pigs (n = 12) that started eating during the dark periods (indicated by the shaded bars in Figure 2) was limited. This supports our suggestion (Bruininx et al., 2001a) that illumination stimulates the development of feed intake by weanling pigs. Additionally, the pattern of the Kaplan-Meier curves (Kalbfleisch and Prentice, 1980) was also affected by sex (P < 0.01). The number of gilts that refrained from eating after weaning decreased faster than the number of non-eating boars. Other feed intake characteristics and perfor-

5 Pre- and postweaning feed intake of pigs 1417 Table 2. Feed intake (as fed) characteristics a of weanling pigs as affected by creep feed consumption during nursing Creep feed consumption b Postweaning period Eater Non-eater No-feed SEM P-value Number of pigs Initial feed intake (g kg 0.75 d 1 ) c Daily increase (g kg 0.75 d) d Phase 1, d0to8 Total number of visits Visits with feed intake 10.8 e 8.9 f 8.2 f a Data are given as estimated means and SEM. b Eaters and non-eaters were given access to a chromic oxide containing creep feed from d 11 after birth until weaning (d 28). A green color of the feces due to the presence of chromic oxide indicated that a pig had eaten creep feed. Piglets that showed green feces at all three sampling moments were designated as eaters. Piglets that never showed green feces were designated as non-eaters. c Initial feed intake = amount of feed consumed during the 24 h following the first visit with feed intake to the feeding station. d Daily increase = daily increase in feed intake during the period between the day of the first successful visit and the day on which energy intake met or exceeded 1.5 times maintenance levels for energy intake; Feed intake on the first feeding day = total feed intake on the day of the first visit with feed intake divided by metabolic BW. mance traits during phase 1 were not affected by sex (P > 0.10). Although not significant (P = 0.12; Table 2), the amount of feed ingested by the eaters within 24 h after the first feed intake (initial feed intake) was higher than for the non-eaters and no-feed pigs (113% and 82%, respectively). Furthermore, the total number of visits to the feeding stations during phase 1 was not affected (P = 0.61; Table 2) by creep feed consumption. However, the number of visits during which feed was consumed was higher for the eaters (P < 0.05; Table 2) than for the non-eaters and no-feed pigs (21% and 32%, respectively). Thus, postweaning feed intake behavior of the piglets that before weaning already ate solid feed seems more efficient than that of the non-eaters and no-feed pigs. Piglets are thought to spend considerable time engaged in exploratory behavior directed at feed and troughs, which is associated with information gathering (Day et al., 1996; Gardner et al., 2001). Therefore, our data suggest that familiarity with solid food at weaning causes the weanling pig to focus more on feed intake and less on exploratory behavior. As a consequence of the increase in the number of visits with feed intake during phase 1, the ADFI and Table 3. Growth performance a of weanling pigs as affected by creep feed consumption during nursing Creep feed consumption b Postweaning period Eater Non-eater No-feed SEM P-value Number of pigs Weaning weight, kg Phase 1, d0to8 ADFI, g/d 202 c 160 d 143 d ADG, g/d 125 c 72 d 80 d Gain:Feed, kg/kg 0.59 c 0.40 d 0.53 cd Phase 2, d9to34 ADFI, g/d ADG, g/d 454 c 389 d 395 d Gain:Feed, kg/kg 0.71 c 0.67 cd 0.65 d Total period ADFI, g/d ADG, g/d 377 c 314 d 321 d Gain:Feed, kg/kg 0.70 c 0.66 cd 0.64 d a Data are given as estimated means and SEM. b Eaters and non-eaters were given access to a chromic oxide containing creep feed from d 11 after birth until weaning (d 28). A green color of the feces due to the presence of chromic oxide indicated that a pig had eaten creep feed. Piglets that showed green feces at all three sampling moments were designated as eaters. Piglets that never showed green feces were designated as non-eaters. c,d,e Within a row and within a factor means without a common superscript differ (P < 0.05).

6 1418 Bruininx et al. ADG for the eaters were also higher (P < 0.05 and P < 0.01, respectively; Table 3) than for the non-eaters and no-feed pigs. Furthermore, the gain:feed ratio tended to be affected by creep feed consumption (P < 0.10; Table 3). Eaters tended to have a higher gain:feed ratio than non-eaters, whereas the gain:feed ratio of no-feed pigs was intermediate. Although no differences were observed (P > 0.10), ADFI of the eaters during phase 2 and the total 34-d period was systematically higher (Table 3) than that of the non-eaters and no-feed pigs. During both periods the pigs designated as eaters grew faster than the non-eaters and no-feed pigs (P < 0.05). The gain:feed ratios during both phases also tended to be affected by creep feed consumption (P < 0.10; Table 3). During phase 2 and the total period the gain:feed ratios of the eaters were systematically highest. Apart from a higher gain:feed ratio of the barrows compared to the gilts (0.70 vs 0.65) during phase 2 (P < 0.05), average performance was not affected by sex (P > 0.10). Information on relations between individual preweaning feed consumption and individual feed intake and performance after weaning is scarce. Pajor et al. (1991) determined individual creep feed consumption for a limited number of piglets (four litters) by combining the weight of the creep feed removed from the dispensers and a video image of piglet activity at the feeder. In contrast with our results, they did not find an effect of preweaning feed consumption on postweaning gain. These conflicting results may have been caused by the differences in experimental design between both studies. In the present study only good eaters were selected, whereas Pajor et al. (1991) used all littermates after weaning, including piglets that ate little creep feed. In conclusion, these findings on early feed intake characteristics clearly show that the preweaning consumption of creep feed stimulates the early development of feed intake after weaning, resulting in improved performance during d 0 to 8. Moreover, our results show that the favorable effects of preweaning feed intake are also present during the entire 34-d nursery period. However, the amount of creep feed that should be ingested by an individual pig in order to achieve these positive effects can not be determined from the results obtained in this study. Implications Using chromic oxide as an indicator of individual preweaning feed intake and computerized feeding stations to measure individual feed intake after weaning, this study has shown that consumption of a high-quality diet during the suckling period stimulates early postweaning feed intake as well as overall postweaning growth. Considering the concept that early postweaning feed intake is beneficial for postweaning health, these results support the use of creep feeding as a strategy to optimize postweaning health and performance. Literature Cited Appleby, M. C., E. A. Pajor, and D. Fraser Effects of management options on creep feeding by piglets. Anim. Prod. 53: Barnett, K. L., E. T. Kornegay, C. R. Risley, M. D. Lindemann, and G. G. Schurig Characterization of creep feed consumption and its subsequent effects on immune response, scouring index and performance of weanling pigs. J. Anim. Sci. 67: Bruininx, E. M. A. M., C. M. C. van der Peet-Schwering, J. W. Schrama, P. F. G. Vereijken, P. C. Vesseur, H. Everts, L. A. Den Hartog, and A. C. Beynen. 2001a. Individually measured feed intake characteristics and growth performance of group-housed weanling pigs: Effects of sex, initial body weight, and body weight distribution within groups. J. Anim. Sci. 79: Bruininx, E. M. A. M., C. M. 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