Methods of reducing milk replacer to prepare dairy calves for weaning when large amounts of milk replacer have been fed

Invited review: The effect of weaning practices on dairy calf performance, behavior, and health-A systematic review

The aim of this systematic review was to summarize the literature assessing the effects of weaning practices on performance, behavior, and health of dairy calves. Only published, peer-reviewed articles written in English and specifically assessing the effects of weaning treatments on dairy calves were eligible for inclusion. Studies had to include 2 or more treatment groups that addressed at least one of 4 interventions: weaning age (i.e., when milk was fully removed), weaning duration (i.e., number of days from start of milk reduction to when milk was fully removed), weaning criteria (e.g., age vs. intake), or alternative weaning methods (e.g., water dilution). Outcome measures could include starter intake, growth (BW or ADG), behaviors (5 specific sucking behaviors; play behavior; lying behavior; vocalizations; unrewarded visits to an automated milk feeder), and health (mortality rate, diarrhea, and respiratory illness). We conducted 3 targeted searches using Web of Science and PubMed. The articles underwent a 2-step screening process, resulting in a final sample of 44 studies. The majority of studies investigated weaning age (n = 22), followed by weaning duration (n = 13), weaning criteria (n = 9), and other weaning methods such as dilution, linear versus step-down milk reduction, or meal-based approaches (n = 6). There was consensus for positive effects (or at least no negative effects) on overall growth of calves weaned at later ages, over longer durations, based on starter intake, or weaned using step-down or meal-based milk removal approaches. This is despite reduced starter intake in calves weaned at later ages; most studies found improved starter intake in calves weaned over longer durations. Weaning based on starter intake had superior growth and feed intakes compared with calves weaned at a fixed earlier age. Few studies assessed interactive effects of weaning method and milk allowance. However, weaning after 8 wk appears to support superior weight gain, provided preweaning milk allowances are adequate (above 6 L/d). Weaning can lead to hunger-related behaviors and reduced welfare, yet only half of the studies assessed the effects of weaning method on calf behavior. Weaning at later ages can reduce signs of hunger (based on unrewarded visits to the milk feeder), but it is unclear if weaning over longer durations or weaning by starter intake reduces or prolongs hunger. There was little consensus among the few studies that measured oral behaviors of calves. Positive welfare indicators, such as play behavior, were rarely measured, yet are crucial to understanding the emotional states of calves during this potentially stressful diet transition. Health was rarely the primary objective of the study, with low sample sizes to conduct statistical comparisons. Overall, there remains significant knowledge gaps in our understanding of how best to wean calves. A successful weaning program must minimize signs of hunger while promoting high growth and feed intakes, so we encourage future work to include behavioral indicators of hunger and positive welfare to evaluate how weaning methods are experienced by the calf.

Rumen Transition from Weaning to 400 Pounds

Rumen development from weaning, 200 pounds (91 kg) to 400 pounds (181.2 kg), is critical and depend on proper papillae development. Papillae development is tied to propionic and butyric acid production in the rumen, and this favors a diet based on concentrate. Forage intake produces acetic acid, which does not promote papillae development. Previous research illustrates that although increasing forage intake as a percentage of the dry matter diet increases rumen size, it shows a reduction in papillae length compared with diets containing a lower percentage of forage and a higher percentage of concentrate intake.

Early step-down weaning of dairy calves from a high milk volume with glutamine supplementation

Weaning dairy calves from a high milk volume (≥8.0 kg/d) can negatively affect the growth and welfare even if it is performed in a step-down manner. Supplementation of Gln improved gut development of preweaning calves and mitigated weaning stresses of piglets to extents achieved with antibiotics. The study objective was to examine the effect of initiating a step-down weaning scheme with a Gln supplement at an early age on calf starter intake (CSI), average daily gain (ADG), and paracellular permeability of the intestinal epithelium of calves fed a high volume of milk (9.0 kg/d). Thirty-six Holstein heifer calves were assigned to 3 treatments (n = 12) as follows: (1) initiating weaning at 49 d of age (LW), (2) initiating weaning at 35 d of age (EW), and (3) initiating weaning at 35 d with a Gln supplement (2.0% of dry matter intake) from 28 to 42 d of age (EWG). Calves were fed 9.0 kg/d of whole milk until weaning was initiated by abruptly decreasing the milk volume to 3.0 kg/d. Weaning was completed once calves achieved ≥1.0 kg/d of CSI. The paracellular permeability of the intestinal epithelium was assessed with lactulose-to-mannitol ratio (LMR) in the blood on 1 d before, and 3 and 7 d after the initiation of weaning. The blood was analyzed for haptoglobin, lipopolysaccharide-binding protein (LBP), and metabolites including AA. The CSI increased once milk volume was restricted in all treatments. The CSI of LW was greater than that of EW and EWG during the first week of weaning. The LW, EW, and EWG took 11, 19, and 16 d to achieve ≥1.0 kg/d of CSI and were weaned at 60, 54, and 51 d of age, respectively. The body weight (BW) of LW, EW, and EWG at the initiation of weaning were 68.2, 58.7, and 59.5 kg, respectively. Both LW and EWG achieved similar ADG, but ADG of EW was lower than LW during the first week of weaning. All calves had similar ADG during the second week of weaning. The BW of LW, EW, and EWG at weaning were 74.8, 66.5, and 66.4 kg, representing a 2.0, 1.8, and 1.8-fold increase in birth weight, respectively. All calves had similar BW of 88.6 and 164.3 kg at 10 and 20 wk of age, respectively. Regardless of the age, serum haptoglobin and plasma LBP concentrations increased on d 3 and returned to baseline concentrations on d 7 during weaning. The EW had a lower plasma LBP concentration than LW and EWG on d 3 during weaning. The LMR was similar between treatments on d 3 but increased by 44% for EW and LW on d 7, whereas the LMR of EWG remained unchanged during weaning. The postprandial serum concentration of Gln, Met, Trp, and β-hydroxybutyrate were greater for EWG than EW during weaning. Beginning step-down weaning at 35 d with a Gln supplement can help maintain the gut barrier function and wean dairy calves with a satisfactory CSI at 7 wk of age without affecting postweaning growth.

Effect of a milk byproduct-based calf starter feed on dairy calf nutrient consumption, rumen development, and performance when fed different milk levels

The objective of this study was to investigate the effects of a milk byproduct-based starter pellet, high in lactose, on feed intakes, growth, and rumen development when calves were fed either a high or low level of milk. This was done by using a 2 × 2 factorial design, with 120 Holstein heifer calves randomly assigned to 1 of 2 milk treatments and 1 of 2 feed treatments upon enrollment at birth. Calves were either assigned to a low (LM) or high (HM) level of milk replacer by an automated milk-feeding system for individually-housed calves. The LM treatment calves were offered 6 L/d (150 g/L; 1.2 L, 5×/d), whereas HM treatment calves were offered 15 L/d (150 g/L; 3 L, 5×/d) of milk replacer. Calves were also assigned to a milk byproduct- (whey) based starter feed treatment (WF), or a grain-based starter ration (95% concentrate starter pellet, 5% chopped wheat straw) feed treatment (GF). All calves were offered their treatment feed starting on d 5, with water offered ad libitum from d 0. The WF treatment calves were offered 150 g/d of the milk byproduct-based pellet until they consumed the entirety for 2 out of 3 consecutive days. At this point, WF treatment calves received 150 g of the milk byproduct-based pellet top dressed onto the grain-based ration to allow for ad libitum feed consumption until weaned, when they only received the grain-based ration postweaning (d 64-77). Calves on the GF feed treatment received only the grain-based ration. All calves were gradually weaned from d 43 to 63. By design, calves on the HM treatment consumed greater levels of milk than LM treatment calves for the majority of the days in the preweaning phase (8.9 ± 0.11 vs. 5.5 ± 0.11 L/d; SE). Calves on the GF and WF treatments consumed similar amounts of milk in the preweaning phase (7.2 ± 0.11 vs. 7.2 ± 0.11 L/d); however, there was a milk and feed treatment interaction detected for milk consumption in the weaning phase, with HM-GF calves drinking more milk than the other treatments and HM-WF calves drinking more milk than both LM-GF and LM-WF calves. The WF treatment calves had greater solid feed intake during the preweaning phase than GF treatment calves, with no feed intake differences in the weaning or postweaning phases. The WF calves drank more water in the preweaning phase than GF calves. Average daily gain was similar throughout the study between the GF and WF treatment calves. Rumen physiological measures were all similar by the end of the trial (d 77) regardless of feed or milk treatment, suggesting similar rumen development postweaning. Overall, regardless of the level of milk fed, offering the milk byproduct-based starter pellet may increase preweaning feed intake, along with water consumption. However, both feed and milk treatments had similar performance and rumen development measures by the end of the trial.

Effects of milk replacer feeding rate and fat content on Jersey calf nutrient digestion and performance to 4 months of age

This study evaluated effects of milk replacer (MR) feeding rate and fat concentration in MR on total-tract digestion (TTD) and growth performance in Jersey calves. Jersey heifer calves (n = 100, 2 blocks of 50; initially 30 ± 3.0 kg of body weight; 4-11 d of age) were randomly assigned to 1 of 4 treatments in a 2 × 2 factorial arrangement of MR feeding rate [454 g for 42 d, and 227 g for 7 d (MOD); or 454 g for 7 d, 681 g for 35 d, and 341 g for 7 d (HI), as-fed basis] and MR fat content (17 or 24% fat as-fed basis). Milk replacers (24% crude protein as-fed basis) were reconstituted to 14% solids and fed in 2 equal feedings for 42 d, and then mornings only for 7 d. Textured calf starter (21% crude protein, 40% starch, dry matter basis) and water were offered for ad libitum consumption. From d 57 to 112, calf starter was mixed with 5% chopped grass hay. Calves were housed individually to d 56 and housed in groups (4-5 calves/pen) from d 57 to 112. Estimates of TTD were measured in 5 calves/treatment (block 1) at wk 3 of the study using acid-insoluble ash as an indigestible marker. From 0 to 56 d, calf starter intake (CSI) was greater for MOD vs. HI and 17 versus 24% fat; average daily gain was greater for HI versus MOD; and hip width change was greater for 17 versus 24% fat. Estimates of organic matter TTD were greater for HI versus MOD, but neutral detergent fiber TTD was greater for MOD versus HI and for 17 versus 24% fat. From 57 to 112 d, hip height change was greater for MOD versus HI, and hip width change was greater for 17 versus 24% fat. In this study, feeding Jersey calves more MR improved preweaning average daily gain, but had a negative effect on CSI and likely rumen development, as neutral detergent fiber TTD was reduced at 3 wk and frame growth was reduced from d 57 to 112. This resulted in similar final calf body weights between MR feeding rates at the end of the study. No benefits were observed for feeding more fat in MR as CSI or for NDF digestibility, and frame growth was reduced.

Effects of step-down weaning implementation time on growth performance and blood metabolites of dairy calves

The current study evaluated the effects of step-down weaning implementation time on starter feed intake, growth performance, blood metabolites, and ruminal pH in dairy calves. A total of 48 Holstein dairy calves (24 male and 24 female; 3 ± 1 d old; 41.2 ± 1.8 kg of body weight) were assigned (n = 12 per treatment; 6 male and 6 female) to 4 experimental treatments in a completely randomized block design. All calves were fed 6 L/d of milk from d 3 to 10 of age, and the treatments consisted of the following: calves were offered 8 L/d of milk from d 11 to 28 of age and then 4 L/d from d 29 to 63 (Step-28; total milk offered = 326 L); calves were offered 8 L/d of milk from d 11 to 42 of age and then 4 L/d from d 43 to 63 (Step-42; total milk offered = 382 L); calves were offered 8 L/d of milk from d 11 to 56 of age and 4 L/d from d 57 to 63 (Step-56; total milk intake = 438 L); and calves were fed 8 L/d of milk from d 11 to 63 of age and abruptly weaned (control; total milk offered = 466 L). All calves were housed individually in pens and had ad libitum access to water and solid feed throughout the experiment. All calves were completely milk weaned on d 64, and their performance was measured until d 80 of age. During the experiment, the starter intake (kg/d and % of body weight) was greater in calves in the Step-28 group compared with those in the other groups. However, the total metabolizable energy intake was greater in the Step-56 calves compared with the other calves. Overall, the average daily gain (ADG), feed efficiency (ADG/dry matter intake), and ADG/total metabolizable energy intake were similar across the treatments. Circulating glucose, β-hydroxybutyrate, blood urea nitrogen, albumin, total protein, alanine aminotransferase, and aspartate aminotransferase, as well as ruminal pH, were not affected by the treatments. The implementation of step-down weaning in early life (4-6 wk of age) could stimulate solid feed intake compared with weaning at a later age with no negative effect on performance.

Effects of feeding different amounts of milk replacer on growth performance and nutrient digestibility in Holstein calves to 2 months of age using different weaning strategies

Growth and the digestibility of nutrients can be greatly affected by diet preweaning and the rate at which calves are weaned. A 2 × 2 factorial design [moderate (MOD) or high (HI) milk replacer (MR) feeding rates and abrupt (AB) or gradual (GR) weaning] was used to compare these effects. Calves (n = 50) were randomly assigned to 1 of 4 treatments: MOD-AB, MOD-GR, HI-AB, and HI-GR. Calves assigned to MOD-AB were fed 0.66 kg of MR for the first 42 d and then 0.33 kg for the last 7 d; those assigned to MOD-GR were fed 0.66 kg of MR for 28 d, 0.33 kg for 14 d, and 0.17 kg for the last 7 d; those assigned to HI-AB were fed 0.66 kg of MR for 7 d, 0.82 kg for 7 d, 1.1 kg for 28 d, and 0.66 kg for the last 7 d; and those assigned to HI-GR were fed 0.66 kg of MR for 7 d, 0.82 kg for 7 d, 1.1 kg for 14 d, 0.66 kg for 14 d, and 0.33 kg for the last 7 d. All calves received the same MR [25% crude protein (CP), 17% fat; dry matter (DM) basis] and were given ad libitum access to water and a textured starter (42% starch and 20% CP). On d 26 to 30 and d 45 to 49, a fecal sample was taken from 5 calves in each treatment via the rectum to estimate apparent digestibility coefficients (dC). Apparent dC of DM, organic matter, and fat were greater for HI versus MOD calves. Apparent dC of neutral detergent fiber, acid detergent fiber, and sugar were greater for MOD versus HI calves. Apparent dC of DM was greater for AB versus GR calves [90.9, 89.0 ± 0.5384 (standard error)], and the apparent dC of acid detergent fiber was greater for GR versus AB calves (39.5, 32.3 ± 1.67). Feed efficiency was greater for HI versus MOD and AB versus GR. There were no significant differences between CP or starch dC based on treatment, and no interactions were observed. Starter consumption was greater for MOD calves compared with HI calves, and GR calves consumed more than AB calves. These results suggest that providing calves high amounts of MR preweaning enhanced readily available nutrient dC, but providing moderate amounts of MR resulted in increased fibrous fraction dC. Accordingly, the AB weaning strategy had higher dC for DM and organic matter, but there was a depression in fiber dC.

Symposium review: Re-evaluation of National Research Council energy estimates in calf starters

Provision of nutrients in appropriate amounts to meet nutrient requirements for growth, production, and reproduction is the basis for modern animal nutrition. Ration formulation systems predict nutrient requirements based on numerous inputs and then predict nutrient supply based on predicted intake and nutrient content of feeds. Energy systems are used to predict energy supply based on gross caloric content of feeds followed by adjustments for digestion and metabolism of ingested energy. Many models of energy supply use static coefficients of digestibility based on nutrient composition of feed. Other models partition digestion dynamically between ruminal and postruminal digestion but use static estimates of intestinal digestibility to predict energy supplied to the animal. In young calves, both ruminal fermentation and intestinal digestion are underdeveloped; therefore, existing models of energy supply might overestimate the energy available before complete gastrointestinal maturation. In a series of experiments, we reported that total-tract digestion of nutrients changes with advancing age and nutrient intake. Total-tract digestion was measured in calves from 3 to 16 wk of age when fed different amounts and types of milk replacers. Calves were also fed different types of calf starter for ad libitum consumption. Total-tract digestibility of protein, fat, neutral detergent fiber, and nonfiber carbohydrate (NFC) was used to calculate the metabolizable energy (ME) in starter. We used nonlinear regression to estimate the contribution of protein and fat from starter and milk replacer before weaning. Early in life, calculated ME of starter was low and increased with increasing intake of NFC. Cumulative intake of NFC was more highly correlated with changing ME values than other indices, including age, intake of milk replacer, or intake of other nutrients in starter. When calves consumed at least of 15 kg of NFC, ME calculated from digestibility measurements was similar to the ME calculated using National Research Council equations and indicated maturation of gastrointestinal digestion. Our data suggest that intake of NFC is critical to gastrointestinal maturation and the calf's ability to extract energy from calf starter.

Effects of gradual and later weaning ages when feeding high milk replacer rates on growth, textured starter digestibility, and behavior in Holstein calves from 0 to 4 months of age

The objectives of this study were to evaluate calf performance, diet digestibility, and behaviors when feeding 4 milk replacer (MR) programs with different MR rates, weaning ages, and MR reduction steps. Male Holstein calves (n = 96; 40 ± 1 kg of body weight; 1 to 2 d of age) were housed in individual pens for 56 d. Feeding programs for MR were 0.66 kg for 35 d; then 0.33 kg for 7 d fed only in the a.m. (0.6 kg); 0.66 kg for 7 d, 0.82 kg for 35 d, 0.33 kg for 4 d in a.m. only, and 0.22 kg for 3 d in a.m. only (0.8 kg); 0.66 kg for 7 d, 0.82 kg for 7 d, 1.1 kg for 21 d, 0.82 kg for 7 d, 0.33 kg for 4 d in a.m. only, and 0.22 kg for 3 d in a.m. only (1.1 kg); and ad libitum allowance for 35 d, 0.82 kg for 7 d, 0.44 kg for 4 d in a.m. only, and 0.22 kg for 3 d in a.m. only (ad lib). Calves were fed a common MR [25% crude protein, 17% fat, dry matter (DM) basis]. A textured calf starter with whole corn and oats (20% crude protein and 39% starch, DM basis) and water were fed for ad libitum intake during the nursery trial. Daily behavior duration (rumination, eating, and activity) was continuously recorded from d 1 to 55 for 4 calves/treatment using ear tag accelerometers (CowManager SensOor; Agis, Harmelen, the Netherlands). All calves were moved into groups by MR program (4 calves/pen) at 56 d and fed the same starter blended with 5% grass hay. Fecal samples were collected from individual calves between d 52 to 56 and from pen floors on d 66 to 70 to estimate total-tract digestibility. Data were analyzed as a randomized complete block design with repeated measures when appropriate. Intake of MR averaged 25.3, 35.3, 40.9, and 46.5 kg of DM per calf for 0.6 kg, 0.8 kg, 1.1 kg, and ad lib treatments, respectively. Starter intake was greatest for 0.6 kg compared with others and average daily gain (ADG) differed among all 4 programs with 0.6 kg < 0.8 kg < 1.1 kg < ad lib during d 0 to 56. Intake of MR for ad lib was highly variable and was reflected in ADG. Daily rumination, eating, and activity durations did not differ among treatments from d 1 to 55 of the nursery trial. Digestibility of DM, organic matter, acid and neutral detergent fiber, and sugar at d 52 to 56 were greater for 0.6 kg versus ad lib. Digestibility of DM at d 66 to 70 differed for all treatments with 0.6 kg > 0.8 kg > 1.1 kg > ad lib and was mostly influenced by fiber digestibility. During the grower trial (d 56 to 112), ADG was greater for 0.6 kg versus 1.1 kg and ad lib. Hip width change was greater for 0.6 kg versus other treatments. Feeding more than 0.6 kg/d of MR increased ADG preweaning, but reduced diet digestibility postweaning resulted in similar calf BW and frame size by 4 mo of age among MR feeding programs.

Effect of milk replacer program on calf performance and digestion of nutrients with age of the dairy calf

Calves fed large amounts of milk replacer (MR) gain more body weight preweaning than calves fed less-aggressive programs; however, postweaning growth may be reduced. Limited research suggests that less than optimal digestion of the postweaned diet due to large amounts of MR with reduced dry feed intake preweaning may contribute to growth impairment postweaning. Current research was conducted to compare growth and postweaning digestion in 3-d-old male Holstein calves fed various MR programs. The MR programs were a conventional [CON; 0.44 kg of dry matter (DM) 21% crude protein (CP), 21% fat powder fed for 42d], moderate (MOD; 0.66 kg of DM 27% CP, 17% fat powder fed for 42d), and aggressive program (AGG; up to 0.87 kg of DM 27% CP, 17% fat powder fed for 49d). All calves were fed a 20% CP textured starter and water ad libitum for 56d. The trial used 96 calves (initially 41 ± 1.9 kg of body weight) received 5 wk apart in 2 groups of 48 calves. During d 51 to 56, fecal samples were collected from 5 calves per treatment randomly selected from calves in the first group. Selected nutrients and acid-insoluble ash (used as an internal flow marker) were analyzed in the starter and feces to estimate digestibility. Data were analyzed as a randomized complete block design with starting time of each group of calves as a block. Repeated measure analysis was performed on overall (0 to 56d) data. Means were separated with a protected least significant difference test. Pen was the experimental unit. Calves fed CON had the least average daily gain [CON=0.35, MOD=0.51, and AGG=0.55 kg/d; standard error of the mean (SEM)=0.018], feed efficiency (CON=0.35, MOD=0.49, and AGG=0.48 gain/feed, SEM=0.016), and change in hip width (CON=3.3, MOD=4.1, and AGG=4.1cm, SEM=0.20) compared with calves fed other programs. Calves fed AGG had the greatest change in BCS and least starter intake compared with calves fed the other programs. Digestibility of organic matter was 79, 78, and 68% and neutral detergent fiber was 54, 51, and 26% for calves fed programs CON, MOD, and AGG, respectively, and were least for calves fed AGG. These results indicate that postweaning digestion is lower than optimal and contributes to lower postweaning growth in calves fed aggressive compared with conventional or moderate MR programs.

Weaning age affects growth, feed intake, gastrointestinal development, and behavior in Holstein calves fed an elevated plane of nutrition during the preweaning stage

Recent research has revealed potential advantages of feeding an elevated plane of nutrition to calves during the preweaning period. However, calves fed more nutrients preweaning may be more susceptible to depressed growth and weaning stress during the transition from liquid to solid feed. The objective of this study was to investigate the relationship between the age of weaning and feed intake, and its influence on growth, gastrointestinal development, and behavioral indicators in dairy calves fed an elevated plane of nutrition during the preweaning period. To meet this objective, 20 female Holstein calves were randomly assigned at birth to be weaned at 6 or 8 wk. Milk replacer (mixed at 150 g/L) was offered at 1.2 kg/calf per day in 2 meals until a 1-wk step-down, when meals were reduced by 50% 1 wk before weaning. Daily starter, chopped oat straw, water intake, and weekly body weights were measured until d 70 of life. To assess digestive tract development, rumen fluid, fecal, and blood samples were taken before and after weaning (d 35, 49, and 63) and analyzed for ruminal short-chain fatty acids, blood β-hydroxybutyrate, and fecal starch, respectively. Behavioral indicators of weaning stress, including vocalizing and non-nutritive oral behavior, were measured by visual observation for 1 h, 3 times per week, before the second feeding of the day during the period from 2 wk before weaning to 2 wk after weaning. The calves weaned at 8 wk compared with 6 wk had higher average daily gain for the week preweaning (0.79±0.09 vs. 0.34±0.10 kg/d) and postweaning (1.05±0.09 vs. 0.35±0.11 kg/d), and were heavier at d 70 (99.9±1.81 vs. 91.0±2.26 kg). From 5 to 8 wk of age, starter and water intakes were lower in calves weaned at 8 wk of age. However, overall starter intake did not differ during the last week of the experiment. Furthermore, calves weaned at 8 wk compared with 6 wk had higher starter intake for 1 wk preweaning (1.36±0.13 vs. 0.40±0.08 kg/d) and postweaning (2.51±0.20 vs. 1.16±0.15 kg/d). In both treatments, weaning increased ruminal short-chain fatty acids, blood β-hydroxybutyrate, and fecal starch, yet the differences between the week before and after weaning were greater for calves weaned at 6 wk compared with those weaned at 8 wk. Treatment × week relative to weaning interactions indicated that several behaviors varied between early- and later-weaned calves during the week before weaning; calves weaned at 6 wk tended to exhibit 75% more non-nutritive oral behavior and spent 55% less time ruminating, and 36% less time lying compared with calves weaned at 8 wk. Under the conditions of this study, the results suggest that calves fed an elevated plane of nutrition preweaning have higher starter intakes and average daily gain during the weaning period when weaning is extended from 6 to 8 wk of age.

Plane of nutrition influences the performance, innate leukocyte responses, and resistance to an oral Salmonella enterica serotype Typhimurium challenge in Jersey calves

Two experiments investigated how plane of nutrition influences performance, leukocyte responses, and resistance to an oral Salmonella enterica serotype Typhimurium challenge. In experiment 1, 46 (2±1 d of age) calves were randomly assigned to 2 diets: a low (LPN; n=23) and high plane of nutrition (HPN; n=23). The LPN calves were fed 409 g/d of dry matter (DM) of a 20% crude protein and 20% fat milk replacer, whereas HPN calves were fed 610 and 735 g/d of DM of a 28% crude protein and 25% fat milk replacer during wk 1 and 2 to 6, respectively. In experiment 2, 20 bull calves (LPN; n=11 and HPN; n=9) were orally challenged on d 80 with 1.5×10(7) cfu of Salmonella Typhimurium (ATCC #14028). The HPN calves had a greater incidence (87.5 vs. 45.5%) and duration of days with high fecal scores (5.5 vs. 3.5 d). The LPN calves had greater neutrophil surface expression of L-selectin on d 7, 21, and 42. Following the Salmonella Typhimurium challenge, calf starter DM intake was greater among the HPN calves. The percentage of neutrophils producing an oxidative burst was also greater among HPN calves on d 1 to 5 after the challenge. Similarly, the intensity of the oxidative burst tended to be greater among the HPN calves on d 2 and 3 postchallenge. The secretion of tumor necrosis factor-α from whole-blood cultures stimulated with lipopolysaccharide tended to be greater on d 1 and was greater on d 5 and 6 among HPN calves. The median ranks of haptoglobin concentrations were greater and plasma zinc concentrations tended to be decreased among LPN calves. These data indicate that feeding a HPN to Jersey calves improved average daily gain and feed efficiency, but increased the incidence of high fecal scores during the first few weeks of life; however, the HPN Jersey calves may be more resistant to Salmonella Typhimurium after weaning.