Feed Intake Pattern Research Articles

Nutritional Approaches to Minimize Subacute Ruminal Acidosis and Laminitis in Dairy Cattle

Abstract Lameness and subacute ruminal acidosis (SARA) both appear to be very prevalent throughout the US dairy industry. Reduced ruminal efficiency, liver and lung abscesses, and laminitis are all thought to be related to SARA. Both the nutritionist and dairy managers are responsible for the delivery and consumption of a ration that is likely to produce a ruminally healthy pH. Nutritionists should consider the expected amount of physically effective neutral detergent fiber provided by ration ingredients, along with their expected ruminal fermentabilities and resultant microbial acid production. Environmental conditions, such as heat stress, overcrowding, and uncomfortable stalls, which may alter feed intake patterns and animal behavior, should also be considered in ration formulation. Additional amounts of physically effective neutral detergent fiber, and/or a reduction in ruminal nonstructural carbohydrate availability, may be warranted during times of increased animal stress. Higher levels of intake may also predispose the rumen to SARA, since salivary buffer secretion may not adequately compensate for additional acid production. Forage dry matter should be determined twice weekly, or more frequently if results vary by more than 5 percent of the dry matter value. Ration variability can be further reduced by premixing individual forages, or at least attempting to make each loader bucket of feed a uniform mix obtained from the entire height or face of the bunker silo. Ingredient sequencing and mixing time should be standardized on a given dairy. Techniques to minimize sorting, including frequent feed pushups, the addition of water or a low dry matter by-product, and appropriate forage processing, should be adopted by managers.

Feed intake, digestibility and fermentation patterns of beef cattle fed chaff and whole or ground maize grain

Feed intake, digestibility and fermentation patterns of beef cattle fed chaff and whole or ground maize grain

Effect of Stepped Pattern of Feed Intake Using Rice Straw as Roughage Source on Regulation of Growth, Reproduction and Lactation in Dairy Heifers

An attempt was made to improve the efficiency of growth and lactation performance of dairy heifers subjected to a stair-step growth scheme using rice straw as the sole roughage source. Twenty-four young Holstein heifers were randomly assigned to either control or test group. The control diet met the National Research Council (NRC) requirement, with heifers calving at 24 to 26 mo of age. The test group was individually fed according to a schedule of 3, 2, 4, 2, 5 and 2 mo in which feed intake was alternately 20% below or 25% above the NRC requirements. Heifers on the stair-step growth pattern gained more body weight and consumed less dry matter (10.80 and 11.22%, respectively), resulting an increasing growth efficiency compared with the control. Body condition, first estrus, first conception, services per conception and calving difficulty (data not shown) were not affected. Milk yield of the test group was 8.5% higher than that of the control group. During the early lactation period, the milk yield was significantly higher in the stair-step group than in that of the control group (p<0.05). Milk composition was not affected by compensatory growth induced by the stair-step scheme. Also, weight at calving and calf growth performance was not affected by stair-step growth. The results indicate that using rice straw as a sole roughage source in a stair-step compensatory growth scheme can contribute to the improvement of growth efficiency and early lactation performance. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 6 : 794-798)

Feed Intake Pattern and Growth Performance of Indian Major Carps, Common Carp and Freshwater Prawn in a Rice-fish Integration System

Feed Intake Pattern and Growth Performance of Indian Major Carps, Common Carp and Freshwater Prawn in a Rice-fish Integration System

Genetic parameters for daily feed intake patterns of growing Dutch Landrace gilts

Daily feed intake (DFI) was described as a function of days on test using a spline random regression model. Order of fit for the spline random regression model was varied, models were compared using Schwarz's Bayesian Information Criterion. The objective was to investigate whether there are genetic differences in DFI patterns. Data were DFI records of 257 growing gilts, which had ad libitum access to food. Gilts were 94 days old at start of test. All gilts were from a Dutch Landrace line. Number of random regression coefficients was varied from zero to nine for both random effects (animal and permanent environment), the model with four random regression coefficients resulted in the most optimal fit. Six traits were derived to capture differences in DFI patterns, average DFI over test, variance of DFI over test, DFI at day 5 on test, DFI at day 50 on test, DFI at day 95 on test and the difference between DFI at day 95 and day 5. Heritability for DFI decreased from 0.53 at 5 days on test to 0.24 at 95 days on test. Genetic correlations between DFI at 5 days on test and 95 days on test, and between DFI at 50 days on test and 95 days on test were low (around 0.3). The results suggested that DFI at different days on test could not be regarded as repeated measurements of a single trait with constant variance and heritability. Based on the results presented, it can be concluded that changes in feed intake patterns through selection are possible.

Effects of Casein and Glucose on Responses of Cows Fed Diets Based on Restrictively Fermented Grass Silage

This study was conducted to investigate whether well fed dairy cows given restrictively fermented grass silage diet will respond to incremental glucose and amino acid supply at early stage of lactation. Four rumen-cannulated Finnish Ayrshire cows were used in a 4×4 Latin square experiment with 14-d periods. The cows were fed good quality restrictively fermented grass silage ensiled with a formic acid additive for ad libitum intake. A concentrate mixture consisting of barley (85%) and solvent extracted rapeseed meal (11.4%) was given at a rate of 9 kg/d. The four treatments were continuous abomasal infusions of water (control), casein 300g/d, glucose 300g/d, and casein 300g/d + glucose 300g/d. The infusions had only minor effects on feed intake, diet digestibility, or rumen fermentation pattern. Both casein and glucose infusions increased milk, protein and lactose yields the effects being partly additive on the combined infusion. Infused casein increased milk protein and urea as well as plasma urea concentrations. Both casein and glucose tended to increase plasma glucose concentration. Casein increased arterial plasma concentrations of essential amino acids (EAA), branched-chain AA (BCAA), and total AA (TAA). Both casein and glucose, although glucose usually less than casein, increased arteriovenous differences of EAA, nonessential AA, BCAA, and TAA. Extraction efficiencies of AA were higher for glucose than for casein. Mammary plasma flow was at highest on the control diet, but reduced owing to infused nutrients, the reduction being less with combined rather than separate infusions of casein and glucose. Based on the partly additive increases in milk production parameters and changes in plasma metabolites, it is suggested that glucose alone increased milk protein yield by sparing AA from hepatic utilization, while casein increased both supply of AA and glucose. It was concluded that cows at early stage of lactation fed diets comprising of restrictively fermented grass silage and a cereal-based concentrate suffer from both limited AA and glucose supplies.

Genetic change of feed intake curves in growing pigs using non‐linear two‐stage genetic analysis and linear random regression models

SummaryLongitudinal data of daily feed intake from 5245 young boars were analysed in this study in order to improve feed efficiency by changing the feed intake curve. Individual logistic and linear‐segmented functions were fitted, based on daily data of feed intake per boar, recorded during a test period of 9 weeks. Heterogeneous variance was considered by means of the power‐of‐the‐mean variance model. The mean estimated day on test corresponding to maximum increment in feed intake varied from 71 to 81 days using logistic function, and the mean estimated day on test at which the feed intake plateau was reached varied from 45 to 48 days on test, using a linear‐segmented function. High differences in the individual variation pattern of feed intake were obtained. A mixed model was fitted to individual estimates of function parameters. The uncertainty in individual estimation was taken into account by incorporating the estimated asymptotic covariance matrices. Estimates of heritability for parameters characterizing feed intake at the beginning of the test period ranged from 0.03 to 0.30. Selection based on parameters of a logistic function, using absolute residual estimation of variance heterogeneity, reduced feed intake at the end of the test period by 0.2 kg/day, while feed intake at the beginning of the test was slightly modified. With increasing individual information on daily feed intake, the two‐stage method was recommended. If individual observations on daily feed intake are sparse, random regression models were preferred in order to change the feed intake curve for breeding purposes.

Random regression to model genetically the longitudinal data of daily feed intake in growing pigs

The objective of this study was the development of a genetic statistical method for longitudinal data of daily feed intake in growing pigs using random regression models (RRM) in order to change the pattern of feed intake by selection. Besides a quadratic RRM for additive genetic effects, different combinations of covariance structures for permanent environmental effects using RRM and for temporary residual effects were fitted to individual information from 5245 boars (2938 of line 3, 2307 of line 4) in order to obtain the best fitting model for daily feed intake recorded during a test period of 10 weeks. Based on Akaike’s Information Criterion, the parsimonious model included a constant diagonal covariance structure for the permanent environmental effects and a heterogeneous autoregressive-moving-average structure of order (1,1) for temporary residual effects. Estimates of the autocorrelation were 0.80 (line 3) and 0.81 (line 4) and estimates of the moving-average components were 0.15 (line 3) and 0.11 (line 4). Estimates of heritabilities were low and increased from 0.02 to 0.06 during the test, with the highest estimates in the seventh week on test. The low heritabilities were only due to a higher residual variance when using individual daily records of feed intake, whereas additive genetic variances (0.01 to 0.04 kg 2) were similar to estimates using average records of feed intake. Genetic correlations between intercept and linear regression coefficients were positive within 0.57 and 0.55, those between intercept and quadratic regression coefficients were negative within −0.77 and −0.89, and those between linear and quadratic coefficients were within −0.48 and −0.61 for lines 3 and 4, respectively, indicating the opportunity for changing the feed intake pattern. Additionally, eigenfunctions obtained from the additive genetic (co)variance matrix indicated that a genetic change in feed intake pattern is achievable, e.g. the second major eigenfunction, which explained about 10% of the additive genetic variation, allowed selection for a high increase in feed intake at the beginning of the test period and for reduced feed intake at the end of the test period in order to improve feed efficiency.

Comparison of linear and nonlinear functions and covariance structures to estimate feed intake pattern in growing pigs

The objective of this study was to find the best function and covariance structure to estimate feed intake pattern in growing pigs for breeding purposes in order to optimise the feed intake curve corresponding to lean growth rate. Daily feed intake from 81 group-housed pigs was recorded using electronic feeders. The animals were tested during 120 days on average, from 30 to 119 kg. Polynomials, Kanis, yield–density, segmented and sigmoidal functions showed high similarity in goodness-of-fit. For selection on early feed intake, linear-segmented, logistic and Richards functions resulted in the most usable estimates within the test period. As shown by simulation, parameters of logistic function resulted in the lowest bias. Covariance among residuals of subsequent daily feed intakes was accounted for using the structures variance components, compound symmetry (CS), first-order autoregressive AR[1], first-order autoregressive moving-average ARMA[1,1], heterogeneous CS, heterogeneous AR[1] and the power-of-the-mean variance model. Correlation structure ARMA[1,1] resulted in the best fit of the data, with estimates for autoregressive parameter ρ from 0.90 to 0.97 and for moving average parameter λ from 0.35 to 0.51. The power-of-the-mean variance model was a good characterisation of variance heterogeneity and the final estimated power was 2.008 with standard error 0.3245. Based on these results, linear-segmented and logistic functions were the most parsimonious functions to characterise feed intake from which selection criteria can be derived, such as the age at which the feed intake plateau or the age at which the maximum increment in feed intake per day is reached in order to change feed intake curve corresponding to lean growth curve.

Feed Intake Patterns, Growth Performance, and Metabolic and Endocrine Traits in Calves Fed Unlimited Amounts of Colostrum and Milk by Automate, Starting in the Neonatal Period

Feed intake, growth performance, and metabolic and endocrine traits were studied in male calves fed unlimited (GrAL; n=7) amounts of colostrum for 3 d after birth and mature milk up to d 28 and were compared with calves fed commonly recommended amounts of colostrum and milk (GrRS; n=7). Calves were fed by automates, and software was available to continuously register the time points and amounts of ingested feed up to 11 d of age. Body weight was measured on d 1, 4, 7, 14, 21, and 28, and blood samples were taken on d 1, 2, 3, 7, 14, 21, and 28 to measure several metabolites and hormones. Feed intake of calves fed GrAL increased from d 1 to 4, then remained stable and was always higher than for calves fed GrRS. Total visits (visits with and without milk intake) were higher for GrRS than GrAL, but visits with milk intake were comparable between groups and meal sizes per visit with milk intake were greater in GrAL than in GrRS. Body weight gain was greater in GrAL than in GrRS in wk 1, but not later. There were significant group differences in plasma concentrations of albumin (GrRS>GrAL), nonesterified fatty acids (GrRS>GrAL), cholesterol (GrRS>GrAL; d 28), insulin (GrAL>GrRS), and cortisol (GrRS>GrAL), but not of immunoglobin G, urea, glucose, triglycerides, growth hormone, and glucagon. In conclusion, calves fed ad libitum were capable of ingesting very large amounts of colostrum and milk, even during wk 1 of life, accompanied by a greater body weight gain in GrAL in the first week, whereas in GrRS, the high number of visits without feed intake indicate that these calves reached no repletion. Compared with calves provided restricted amounts of feed, calves with free access to colostrum and milk were characterized by reduced plasma concentrations of nonesterified fatty acids and by a transiently enhanced insulin and reduced cortisol status.

Effects of Slow-release Insulin on Production, Liver Triglyceride, and Metabolic Profiles of Holsteins in Early Lactation

The objective of this experiment was to determine whether there is a dose of slow-release insulin (SRI) that decreases concentrations of plasma nonesterified fatty acids (NEFA) and liver triglyceride (TG) without decreasing plasma glucose concentration, dry matter intake (DMI), and milk yield. Forty-three Holsteins weighing 765±70kg with body condition score of 3.29±0.25 (mean±SD) were fed for ad libitum consumption of the same diet from 2 wk before parturition through 6 d postpartum. Cows were blocked according to actual calving date and parity and then assigned randomly to intramuscular injection of a single dose of 0, 0.14, 0.29, or 0.43 IU of SRI per kilogram of body weight (BW) on d 3 postpartum. On the day of injection, cows were fed hourly to minimize fluctuations in blood hormones and metabolites due to feed intake pattern. Blood samples were collected via jugular catheter every hour from 0 to 24h and every 6h from 24 to 48h postinjection. Pre- and postinjection period liver samples were taken on d 2 and 5 postpartum. One cow injected with 0.29 and two cows injected with 0.43 IU of SRI per kilogram of BW could not complete the trial due to severe hypoglycemia (<20 mg/dl). Both DMI and milk yield during d 3 to 5 postpartum tended to increase quadratically by increasing dose of SRI. Concentrations of serum insulin and glucagon increased linearly, concentration of plasma glucose decreased linearly, and concentrations of plasma NEFA and β-hydroxybutyrate decreased quadratically from 0 to 24h postinjection by increasing dose of SRI. Serum insulin concentrations remained higher in cows injected with SRI (CISRI) than in cows injected with sterile water (CISW; 0 IU of SRI/kg of BW), the quadratic effect of SRI on plasma NEFA concentration continued, and the linear effect of SRI on plasma glucose concentration diminished from 24 to 48h postinjection. Concentration of hepatic TG for CISRI tended to be lower than for CISW, and increasing dose of SRI quadratically decreased hepatic accumulation of TG. Increasing dose of SRI tended to increase concentration of hepatic glycogen (GLY) quadratically and decreased the ratio of TG to GLY quadratically. In conclusion, a low dose of SRI (0.14 IU/kg of BW) could be considered for prophylactic use against hepatic lipidosis and ketosis.

Effect of group size and feeder type on growth performance and feeding patterns in finishing pigs.

The effects of four group sizes (2, 4, 8, and 12 pigs per pen) and two single-space feeder types (conventional and electronic feed intake recording equipment [FIRE]) on feed intake, growth performance, and feeding patterns were determined in 208 crossbred finishing pigs (equal numbers of barrows and gilts) between 84.4 (SD = 0.81) to 112.8 (SD = 1.08) kg BW over a 4-wk period. Pigs were given ad libitum access to a corn-soybean meal-based diet (15.9% CP; 0.79% lysine; 3,328 kcal ME/kg). The floor space allowance was 0.9 m2/pig for all treatments. Growth rates were not different for the two feeder types; however, feed intake was lower and gain:feed ratio higher for pigs on the FIRE feeders (P < 0.01). Feed intake, growth rate, and gain:feed ratio were not different (P > 0.05) among the group sizes. Number of feeder visits per day decreased and feed intake per visit, feeder occupation time per visit, feed consumption rate, and percentage of time the feeder was occupied increased with group size (P < 0.05). Feed intake per visit had the strongest correlation with daily feed intake (r = 0.54; P < 0.01) and was negatively correlated with gain:feed ratio (r = -0.38; P < 0.01). However, the correlations between growth performance and other feeding pattern traits were relatively weak (r < or = 0.30). As group size increased, diurnal variation in number of feeder visits and feed consumed per hour decreased. There was no difference in time spent sitting and standing between the two feeder types. The proportion of time spent eating was generally lower for the larger groups on both feeders. The proportion of time spent lying was similar across group sizes for pigs on the conventional feeders but was greater for pigs in the larger groups on the FIRE feeders. This study suggests that finishing pigs can maintain feed intake and growth rate by changing feeding behavior as group size increases from 2 to 12.

Short-term effects of in-feed supplementation of tetracyclines for disease control on feed intake pattern and growth in weaned pigs

Chlortetracycline (CTC) and oxytetracycline (OTC) are often administered in feed to pigs at extra-label doses to increase the efficacy of disease control strategies, but the bitterness of these antibiotics may significantly depress the voluntary feed intake of pigs at risk, compromising growth and the efficacy of the therapeutic regimen. We examined individual feed intake patterns and growth of 5-week-old pigs that received either drug-free feed ( n=36 pigs) or feed medicated with CTC or OTC at 12-h intervals for a period of 5 days. Each tested drug was mixed in feed at concentrations of 550, 1100, 1650 and 2200 mg/kg ( n≥8 pigs/dose/drug). Neither drug nor dose significantly affected the rate of feed intake (excluding interruptions), duration of meal, and the likelihood of leaving feed uneaten at the end of at least one meal. Average daily gain and feed conversion ratio (FCR) showed similar mean values across treatment groups, but variance of FCR varied significantly: CTC<OTC<drug free. Meal duration and feeding rate, and the likelihood of leaving feed uneaten were significantly influenced by the size of pigs, the occurrence of infection or spontaneous feeding interruptions during the meal. Feeding rate increased with experimental days. Results show that CTC and OTC are not feed deterrents in weaned pigs in the range of therapeutic doses currently used, but other sources of variation in feed intake indicate that drug input could vary among pigs.

Effects of Abomasal Infusions of Histidine, Glucose, and Leucine on Milk Production and Plasma Metabolites of Dairy Cows Fed Grass Silage Diets

Our previous study showed that His was the first-limiting amino acid (AA) for milk protein production in cows fed grass silage and cereal-based supplement. The aim of this study was to identify the second-limiting AA and determine whether glucose was limiting responses to His. Abomasal infusion of His (6.5 g/d), glucose (250 g/d), His (6.5 g/d) + glucose (250 g/d), His 6.5 g/d) + Leu (12 g/d) and His (6.5 g/d) + Leu (12 g/d) + glucose (250 g/d) on milk production and utilization of amino acids by mammary gland was in an incomplete 5 × 6 Latin square design with 14-d periods. The diet was based on restrictively fermented grass silage fed ad libitum and 8 kg/d of concentrate comprised of barley, oats, unmolassed sugar beet pulp, urea, and minerals. The infusions did not affect feed intake, diet digestibility, or rumen fermentation pattern. The molar proportion of propionate in rumen VFA was low (15.5%), suggesting that glucose supply from the basal diet could be limiting. Milk and milk protein yields were increased by His infusion. Infusion of His increased plasma His concentration from 19 to 52 μM but decreased extraction efficiency of His. Infusion of glucose increased plasma glucose concentration, milk lactose concentration, and yield and tended to increase milk protein yield. Responses in milk protein yield to combined infusions of His and glucose were additive, suggesting that the utilization of the first-limiting AA His was limited by glucose supply. Infusion of Leu increased plasma Leu concentration but did not produce any further milk protein yield response compared with the infusions without Leu. It was concluded that the efficiency of utilization of the first-limiting AA His could be improved by increasing the supply of glucose, when the basal diet produces a rumen fermentation pattern low in propionate. Leu was not the second-limiting AA in cows fed grass silage-based diets.

L-threonine supplementation increases the amplitude of the feed intake cycle of rats fed a low-protein zinc-deficient diet.

Rats fed a Zn-deficient diet show characteristic variations in feed intake. These variations were followed by means of a personal computer. The specific feed intake patterns in rats fed a zinc-deficient diet before and after supplementation with protein and several essential amino acids were determined. The high-protein diet decreased the amplitude of feed intake under zinc deficiency, probably because of a decrease in sensitivity to the deficiency. Furthermore, the zinc-deficient diet was supplemented with essential amino acids, and of them L-threonine showed the most marked effect on the increased variability of feed intake.

Voluntary feed intake in autumn calving continental x dairy suckler cows given a grass silage based diet ad libitum

An understanding of the dry matter intake (DMI) capacity of suckler cows is crucial to the provision of adequate nutrition during lactation. However, quantitative data on the likely feed intake patterns of modern continental x dairy suckler cow genotypes is scarce. The objective of the current experiment was to determine voluntary DMI in Simmental x Holstein/Friesian (SIM) and Belgian Blue x Holstein/Friesian (BB) autumn calving suckler cows offered a grass silage based diet ad libitum.

Feed Intake Patterns and Growth Performance of Purebred and Crossbred Meishan and Yorkshire Pigs

Feed Intake Patterns and Growth Performance of Purebred and Crossbred Meishan and Yorkshire Pigs

Effect of group size and feeder type on growth performance and feeding patterns in growing pigs.

The effects of four group sizes (2, 4, 8, and 12 pigs per pen) and two single-space feeder types (conventional and electronic feed intake recording equipment [FIRE]) on feed intake, growth performance, and feeding patterns were determined in growing pigs over a 4-wk period. A total of 416 hybrid pigs (barrows and gilts) were grown from 26.5 (SD = 1.6) to 47.8 (SD = 2.7) kg BW and given ad libitum access to a corn-soybean meal-based diet (17.4% CP; 0.9% lysine; 3,298 kcal ME/kg). The floor space allowance was 0.9 m2/pig for all treatments. Pigs using the electronic feeders had similar growth rates but lower feed intakes (P < 0.01) and higher gain:feed ratios (P < 0.01) compared to those using the conventional feeders. Barrows compared to gilts had higher growth rates (P < 0.05), numerically higher (P > 0.05) ADFI, and similar feed efficiency and feeding pattern. Feed intakes and growth rates were lowest (P < 0.05) for groups of 12 pigs but gain:feed ratio was not affected by group size. Daily feeder occupation time per pig was lower (P < 0.01) for groups of 12 than for groups of 2 or 4 pigs, and feed consumption rate was higher (P < 0.01) for groups of 12 than for groups of 4 pigs. The proportion of time spent eating was lower (P < 0.01) and the proportion of time spent standing was higher (P < 0.01) for pigs in groups of 12 compared to groups of 2. Correlations between ADG and ADFI and feed intake per visit were 0.29 and 0.30, respectively (P < 0.01), between ADG and ADFI and feed consumption rate were 0.27 and 0.31, respectively (P < 0.01), and between ADFI and feeder occupation time per day were 0.33 (P < 0.01). This study suggests that, in growing pigs given access to a single feeder, changes in feeding behavior with increasing group size were not sufficient to maintain feed intake and growth rate.

Effect of Feeding Environment on Performance, Injuries and Behaviour in Growing-finishing Pigs: Group-Based Studies

Ten batches of pigs (608 pigs) were used in this investigation (live weight interval 20-120 kg). Four different feeding systems were tested: one dry feeder, four dry feeders, trough feeding or one wet/dry feeder per pen of 16 pigs, respectively. The one dry feeder treatment led to an increase in skin injuries, a more spread feed intake pattern, an increased variation in carcass meat percentage and an increased variation in daily weight gain (DWG) when the pigs were restrictively fed, compared with observations for the pigs in the four dry feeders treatment. The effect of a reduced number of feeding places was most pronounced when the pigs were fed restrictively. Besides the possible negative financial effects for pig producers, these findings indicated that competition for feed impaired the well-being of the pigs. Pigs fed in a trough had a lower DWG and higher feed conversion ratio than did those fed using four dry feeders, probably due to feed spillage and the different feed intake pattern. Giving pigs the possibility of adding water to the feed increased the daily feed intake when feeding ad libitum, resulting in a higher DWG. It also reduced the negative effects of competition on performance, but not the negative effects on skin injuries.

Effect of Feeding Environment on Performance, Injuries, Plasma Cortisol and Behaviour in Growing-finishing Pigs: Studies on Individual Pigs Housed in Groups

The effect of feeding environment on individual pigs (small, medium and large barrows) housed in groups of 16 pigs was studied. The experiment comprised the following four treatments: trough feeding, four dry feeders, one dry feeder and one wet/dry feeder per 16 pigs, respectively. Performance, skin injuries, plasma cortisol, agonistic behaviour, ingestive behaviour and activity were studied. The effect of competition for feed was most clearly evident for the small pigs. The small animals in the one dry feeder treatment were forced to eat more during the night, had more forced withdrawals from the feeder, and tended to have more scratches and skin injuries than did the small animals in the four dry feeder treatment. It was concluded that this competition led to impaired well-being in the smallest pigs. No significant differences were detected in plasma cortisol levels, when comparing the different feeding systems within each pig size category. Trough feeding greatly affected pig feed intake pattern: during the growing period when pigs had ad libitum access to feed, the pigs fed in a trough ate mostly at feeding times, while the pigs in the four dry feeder treatment ate at times spread out over the entire 24 h period. It was concluded that there was a confounding effect between pig size category (small or large) and feeding system with regard to ingestive behaviour and aggressive interactions at feeding.