Milk Replacer Diet Research Articles

The Effect of Milk Replacer Composition on the Intestinal Microbiota of Pre-ruminant Dairy Calves.

The impact of dietary composition and prebiotics, in promoting the growth of beneficial groups of gut bacteria, is increasingly apparent. Using Illumina MiSeq sequencing of bacterial 16S rRNA genes, this study has aimed to characterize and compare the establishment of the gastrointestinal microbiota in dairy calves given two different commercial milk replacer (MR) diets. MR1 and MR2 contain different levels of macronutrients such as protein and fat. Moreover, differences in manufacturing methods infer that MR2 may contain a greater proportion of conjugated milk oligosaccharides (OS), while MR1 contains more free milk OS. A total of 10 dairy calves, five in each group, were assigned to one of the two MR diets. Freshly voided fecal samples were taken at 0, 7, 14, 28, and 49 days after first consumption of milk replacer. The relative abundance of two individual Bifidobacterium species, which are known to utilize milk OS, and Faecalibacterium prausnitzii were significantly higher at day 7 in the fecal microbiome of calves fed MR2 compared with MR1. These commensal bacteria are widely regarded as probiotic organisms that confer a health benefit on the host. Our findings suggest that the composition of bovine milk replacers can have significant effects on the establishment of the gut microbiota in pre-weaned (neonatal) dairy calves. Better understanding of milk composition-microbiota-host interactions in early life will inform targeted interventions to increase growth and reduce mortality in young animals.

The effect of dietary vitamin D supplementation on sodium-dependent phosphate uptake and expression of NaPi-IIb in the small intestine of weanling pigs.

Two experiments were conducted to investigate the effects of 1,25(OH)2D3 to stimulate Na+-dependent phosphate uptake in Caco-2 cells, and the effects of dietary vitamin D supplementation to vitamin D-deficient nursery pigs on Na+-dependent nutrient uptake and mRNA expression of NaPi-IIb cotransporter and calbindin D(9k) in the jejunum. In Exp. 1, 250,000 Caco-2 cells were seeded on Costar 12 mm Snapwell inserts with a 0.40 µm polycarbonate filter and a seeding density of 0.25 × 106 and studied at 15 d postconfluence. Cells were treated with 10 nM of either 1,25(OH)2D3 or vehicle for 48 h and then mounted in modified Ussing chambers for transepithelial measurements. In Exp. 2, pigs (n=32) were removed from sows at 3 d of age, placed on a vitamin D-deficient milk replacer diet and housed in a room devoid of sunlight and UV light in the range of 280 to 300nm. On d 28, serum 25(OH)D3 concentrations were measured to verify low vitamin D status. Pigs (BW 10.10 ± 0.38 kg) were then individually housed d 28 post-weaning and allotted to 1 of 2 dietary treatments. Dietary treatments consisted of corn-soybean based diets with vitamin D supplementations of 0 or 1,500 IU/kg diet for 12 d. Blood samples were taken from the brachiocephalic vein on the initial (d 0) and final day (d 10,11, or 12) of the study for analysis of serum 25(OH)D3 , P, and Ca. Pigs were euthanized and jejunal segments were harvested and used in modified Ussing chambers and for RNA isolation and subsequent quantitative RT-PCR analysis. In Exp. 1, treating Caco-2 cells with 10 nM 1,25(OH)2D3 resulted in a 52% increase (P < 0.005) in Na+-dependent phosphate uptake compared with cells treated with a vehicle. In Exp. 2, Na+-dependent phosphate and glucose transport did not differ (P > 0.10) among treatment groups. Additionally, NaPi-IIb and calbindin D(9k) mRNA expression were not different (P > 0.10) between treatment groups. No differences (P > 0.10) were detected in final serum P or 25(OH)D3 concentrations between treatments. However, serum Ca linearly increased (P < 0.05) as the concentration of supplemental vitamin D increased in the diet. Overall, while 1,25(OH)2D3 stimulated Na+-dependent phosphate uptake in Caco-2 cells, supplementing diets with 1,500 IU/kg Vitamin D3 from cholecalciferol did not increase jejunal Na+-dependent phosphate uptake or NaPi-IIb mRNA expression over that of pigs fed diets with no supplemental cholecalciferol.

Varying dietary protein and fat elicits differential transcriptomic expression within stress response pathways in preweaned Holstein heifers

Increases in milk replacer dietary energy subsequently increase growth and weight in preweaned dairy heifers. However, the underlying effects of dietary component increases on key functional pathways have yet to be fully investigated. Elucidating these relationships may provide insights into the mechanisms through which protein and fat are partitioned for tissue growth and metabolism. We hypothesized that genes within key growth and metabolic pathways would be differentially expressed between calves fed a protein- and fat-restricted diet and calves fed a protein- and fat-enhanced diet. The objectives of this study were to (1) identify genes differentially expressed between dietary restricted calves and enhanced calves and (2) determine the key regulatory pathways influenced by these genes. Preweaned Holstein heifers (n = 12; 6 ± 0.02 d of age) were randomly assigned to 1 of 2 milk replacer diets: enhanced (28.9% crude protein, 26.2% fat; n = 6) or restricted (20.9% crude protein, 19.8% fat; n = 6). Growth measures included average daily gain and gain-to-feed ratio. After 56 d, calves were killed for tissue collection. Samples from longissimus dorsi, adipose, and liver tissues were collected and RNA was isolated for RNA sequencing analysis. The MIXED procedure of SAS (SAS Institute Inc., Cary, NC) was used to evaluate relationships of growth with dietary energy. Fixed effects included date of collection and time (day). Random effects included sire and birth weight. The RNA sequencing analysis was performed using CLC Genomics Workbench (Qiagen, Germantown, MD), and the Robinson and Smith exact test was used to identify differentially expressed genes between diets. The Protein Analysis Through Evolutionary Relationships (PANTHER) database was then used to identify functional categories of differentially expressed genes. Enhanced calves had increased growth rates and feed efficiency compared with restricted calves (average daily gain = 0.76 and 0.22, respectively; gain-to-feed ratio = 0.10 and 0.06, respectively). There were 238 differentially expressed genes in adipose, 227 in longissimus dorsi, and 40 in liver. We identified 10 genes concordant among tissues. As expected, functional analyses suggested that the majority of genes were associated with metabolic or cellular processes, predominantly cell communication and cell cycle. Overall, it appears that varying levels of dietary protein and fat influence calf growth and development through metabolic processes, including oxidative phosphorylation and glyceroneogenesis. However, protein- and fat-restricted calves appeared to experience metabolic stress at a cellular level, as evidenced by an upregulation in stress response pathways, including genes in the p53 pathway. Calves could be fed at a higher level of protein and fat to decrease the prevalence of metabolic stress at the cellular level, but evidence indicating the presence of inflammatory stress and adipose fibrosis in enhanced calves prompts further investigation of the effects of milk replacer component levels.

Milk replacers supplemented with either L-arginine or L-carnitine potentially improve muscle maturation of early reared low birth weight piglets from hyperprolific sows

As a result of the selection for genotypes with greater sow prolificacy, litter size increased and, concomitantly, average litter birth weight and early postnatal survival rates of low birth weight (L-BtW) offspring decreased. This study compared the impact of l-carnitine (CAR) and l-arginine (ARG) supplemented with a milk replacer and fed to L-BtW piglets born from large litters from days 7 to 28 of age on growth performance, carcass composition, organ and Semitendinosus muscle (STM) development. A total of 30 female and castrated Swiss Large White piglets weaned at 7 days of age were assigned to three milk replacer diets containing either no supplement (CON), CAR (0.40 g/piglet per day) or ARG (1.08 g/kg BW per day). Piglets were kept in pairs in rescue decks (0.54 m2). They were weighed daily and daily allowance of both, feed and ARG, was adjusted accordingly. Thus, feed allowance depended on growth. Each day, the milk replacer was prepared with water (1:4). Feed (allowance: 60 g dry matter/kg BW per day) was offered daily in six equal rations. Feed intake and feed efficiency was assessed for the pairs and apparent total tract-energy and -protein digestibility was determined from days 21 to 28 of age. On day 28, piglets were euthanized, blood samples were collected and the whole STM and organs were weighed. In STM, the size and metabolic properties of myofibers were determined. No difference in growth performance was found between dietary treatments, but piglets from the CAR group tended (P<0.10) to grow faster during the 1st experimental week and consume more feed from days 14 to 21 as compared with piglets of the CON group. A setback in growth in the last week in the CAR group coincided with the lower (P<0.05) energy and protein digestibility. Dietary treatments had no effect on STM and organ weight and myofiber size. Compared with the other groups, there were trends (P<0.10) for blood serum urea and glucose level to be greater in CAR and for non-esterified fatty acid level to be greater in ARG piglets. The greater (P<0.05) ratio of lactate dehydrogenase to either citrate synthase or β-hydroxyacyl-CoA dehydrogenase indicated that the relative importance of the glycolytic compared with the oxidative pathway was greater in STM of CAR and ARG compared with CON piglets. These results suggest that ARG and CAR supplements were beneficial for muscle maturation whereas findings on phenotypic traits were rather unsystematic.

Establishment of a porcine model of indomethacin-induced intestinal injury.

A useful animal model of intestinal injury is pivotal for studying its pathogenesis and developing nutritional interventions (e.g., amino acid supplementation). Here, we propose the use of indomethacin (IDMT) to induce intestinal inflammation in neonatal pigs. Fourteen-day-old piglets fed a milk replacer diet receive intraperitoneal administration of IDMT (5 mg/kg body weight) for 3 consecutive days. On day 4, blood and intestinal samples are obtained for physiological and biochemical analyses. IDMT increases blood DAO activity, I-FABP concentration, neutrophil and eosinophil numbers; intestinal MMP3 mRNA levels, MPO activity, and MDA concentration; but reduces the plasma concentration of citrulline (synthesized exclusively by enterocytes of the small intestine), intestinal GSH-Px activity, and mRNA levels for villin, I-FABP, TRPV6, AQP10, and KCNJ13. Moreover, extensive hemorrhagic spots, thinned intestinal wall, and ulcers in the distal jejunum and ileum are observed in IDMT-challenged piglets. Furthermore, IDMT decreases intestinal villus height and villus surface area in the piglet jejunum. Collectively, this work establishes a porcine model of intestinal injury for designing novel nutritional means to improve gut function in pigs and humans.

Short communication: Supplementation of fructo-oligosaccharides does not improve insulin sensitivity in heavy veal calves fed different sources of carbohydrates

Heavy veal calves (4-6 mo old) often develop problems with insulin sensitivity. This could lead to metabolic disorders and impaired animal growth performance. Studies in various animal species have shown that the supplementation of short-chain fructo-oligosaccharides (scFOS) can improve insulin sensitivity. We therefore studied the effects of scFOS supplementation on insulin sensitivity in heavy veal calves. Forty male Holstein-Friesian calves (BW = 190 ± 2.9 kg; age = 162 ± 1.4 d at the start of the trial) were fed either a control milk replacer (MR) diet or a diet in which one-third of the lactose was replaced by glucose, fructose, or glycerol for 10 wk prior to the start of the trial. At the start of the trial, calves were subjected to a frequently sampled intravenous glucose tolerance test to assess whole-body insulin sensitivity (muscle and hepatic insulin sensitivity). Calves within each dietary treatment group were ranked based on their insulin sensitivity value. Half of the calves received scFOS (12 mg/kg of BW) with the MR for 6 wk (supplementation was equally distributed over the insulin sensitivity range). Subsequently, a second frequently sampled intravenous glucose tolerance test was conducted to assess the effect of scFOS. In addition, fasting plasma levels of glucose, insulin, triglycerides, and cholesterol were determined to calculate the quantitative insulin sensitivity check index and triglyceride:high-density lipoprotein cholesterol ratio (fasting indicators of insulin sensitivity). Whole-body insulin sensitivity was low at the start of the trial and remained low in all groups [1.0 ± 0.1 and 0.8 ± 0.1 (mU/L)-1 · min-1 on average, respectively]. Supplementation of scFOS did not improve insulin sensitivity in any of the treatment groups. The quantitative insulin sensitivity check index and the triglyceride:high-density lipoprotein cholesterol ratio also did not differ between scFOS and non-scFOS calves and averaged 0.326 ± 0.003 and 0.088 ± 0.004, respectively, at the end of the trial. We conclude that scFOS supplementation does not improve insulin sensitivity in heavy veal calves regardless of the carbohydrate composition of the MR. This is in contrast to other animals (e.g., dogs and horses), where scFOS supplementation did improve insulin sensitivity. The absence of an effect of scFOS might be related to the dosage or to metabolic differences between ruminants and nonruminants. Increasing evidence indicates that dietary interventions in veal calves have little or no effect on insulin sensitivity, possibly because of low levels of insulin sensitivity.

The influence of postnatal nutrition on reproductive tract and endometrial gland development in dairy calves

Uterine gland development occurs after birth in cattle and other mammals. The timeline of gland development has been described in various species, but little is known about how postnatal diet influences uterine gland development. This is especially concerning in dairy heifers, where a variety of milk replacer and whole milk nutrition options exist. Little work also exists in cattle to describe how early exposure to steroids influences reproductive tract and uterine gland development. The objective of this work was to determine the effects of early postnatal plane of nutrition and estrogen supplementation on uterine gland development in calves. In both studies, Holstein heifer calves were assigned to restricted milk replacer (R-MR) or enhanced milk replacer (EH-MR) diets. In study 1, calves (R-MR, n = 6; EH-MR, n = 5) were euthanized at 8 wk. In study 2, calves were weaned at 8 wk and administered estradiol (R-MR, n = 6; EH-MR, n = 6) or placebo (R-MR, n = 6; EH-MR, n = 5) for an additional 14 d before euthanasia. Average daily gain and final body weight was greater in both studies in heifers fed the enhanced diet. At 8 wk, EH-MR calves had a greater number of glands and a smaller average gland size, but total gland area was not different from the R-MR group. At 10 wk, uterine gland number and size were not affected by diet or estrogen. Expression profiles of several paracrine mediators of gland development were examined. Increases in transcript abundance for IGF1 and IGFBP3 and a decrease in abundance of WNT7A were detected in calves fed the enhanced diet at 8 wk of age. Plane of nutrition did not affect transcript profiles at 10 wk of age, but estradiol supplementation decreased MET and WNT7A transcript abundance. To conclude, heifer calves on a restricted diet exhibited a uterine morphology and transcript profile suggestive of delayed uterine gland development. These changes appear to be corrected by wk 10 of life. Also, this work provides evidence supporting the contention that early estradiol exposure has detrimental effects on uterine gene expression.

Substantial replacement of lactose with fat in a high-lactose milk replacer diet increases liver fat accumulation but does not affect insulin sensitivity in veal calves.

In veal calves, the major portion of digestible energy intake originates from milk replacer (MR), with lactose and fat contributing approximately 45 and 35%, respectively. In veal calves older than 4 mo, prolonged high intakes of MR may lead to problems with glucose homeostasis and insulin sensitivity, ultimately resulting in sustained insulin resistance, hepatic steatosis, and impaired animal performance. The contribution of each of the dietary energy sources (lactose and fat) to deteriorated glucose homeostasis and insulin resistance is currently unknown. Therefore, an experiment was designed to compare the effects of a high-lactose and a high-fat MR on glucose homeostasis and insulin sensitivity in veal calves. Sixteen male Holstein-Friesian calves (120±2.8kg of BW) were assigned to either a high-lactose (HL) or a high-fat (HF) MR for 13 consecutive weeks. After at least 7 wk of adaptation, whole-body insulin sensitivity and insulin secretion were assessed by euglycemic-hyperinsulinemic and hyperglycemic clamps, respectively. Postprandial blood samples were collected to assess glucose, insulin, and triglyceride responses to feeding, and 24-h urine was collected to quantify urinary glucose excretion. At the end of the trial, liver and muscle biopsies were taken to assess triglyceride contents in these tissues. Long-term exposure of calves to HF or HL MR did not affect whole-body insulin sensitivity (averaging 4.2±0.5×10-2 [(mg/kg∙min)/(μU/mL)]) and insulin secretion. Responses to feeding were greater for plasma glucose and tended to be greater for plasma insulin in HL calves than in HF calves. Urinary glucose excretion was substantially higher in HL calves (75±13g/d) than in HF calves (21±6g/d). Muscle triglyceride content was not affected by treatment and averaged 4.5±0.6g/kg, but liver triglyceride content was higher in HF calves (16.4±0.9g/kg) than in HL calves (11.2±0.7g/kg), indicating increased hepatic fat accumulation. We conclude that increasing the contribution of fat to the digestible energy intake from the MR from 20 to 50%, at the expense of lactose does not affect whole-body insulin sensitivity and insulin secretion in calves. However, a high-lactose MR increases postprandial glucose and insulin responses, whereas a high-fat MR increases fat accumulation in liver but not muscle.

0773 The effect of phase feeding on feed cost, growth, and performance of calves fed milk replacer

Ninety-six 3- to 10-d-old Holstein bull calves with an average initial BW of 44.1 kg (SD 1.67) were shipped from Wisconsin to the Land O'Lakes Research Facility in northwest Iowa. The objective of this study was to evaluate the use of phase feeding with a milk replacer (MR) containing only milk protein in the first phase and a MR using hydrolyzed soy protein modified (HSPM) in the second phase of calf rearing. Calves were randomly assigned according to BW and blood γ globulin to one of four MR diets offered in a 15% solution: 1) 27% CP containing only milk protein, 10% fat (control); 2) phase feeding, 28% CP, 20% fat in Phase 1 and 22% CP, 15% fat with HSPM in Phase 2; 3) phase feeding, 28% CP, 20% fat in Phase 1 and 25% CP, 15% fat with HSPM in Phase 2; and 4) phase feeding, 28% CP, 20% fat in Phase 1 and 28% CP, 15% fat with HSPM in Phase 2. Calves were fed to provide 816 g DM/d during Days 1 to 6 and 1,135 g DM/d during Days 7 to 41, in 2 feedings at 0600 and 1515 h. Calves were offered 567.5 g in one feeding at 0600 h during the last week. Calf starter (22% CP, as-fed basis) was offered ad libitum throughout this 48-d trial. Data were analyzed by Mixed procedures of SAS. Total weight gain, MR consumption, feed:gain ratio, and starter intake did not differ (P > 0.05) among treatments. Total feed costs over the 7-wk trial were significantly lower (P < 0.05) for the three phase-feeding treatments. Calves on the three phase-fed diets performed equally to calves on the control-fed diets and the feed costs were significantly reduced, making this a viable option where applicable.

Supplementation of essential fatty acids to Holstein calves during late uterine life and first month of life alters hepatic fatty acid profile and gene expression

Linoleic acid is an essential dietary fatty acid (FA). However, how the supplementation of linoleic acid during uterine and early life may modify the FA profile and transcriptome regulation of the liver, and performance of preweaned dairy calves is unknown. Our objective was to evaluate the effect of supplementation of essential FA to Holstein calves during late uterine and early life on their hepatic FA profile and global gene expression at 30 d of age. During the last 8 wk of pregnancy, Holstein cattle (n=96) were fed either no fat supplement (control), a saturated FA supplement enriched with C18:0, or an unsaturated FA supplement enriched with linoleic acid. Male calves (n=40) born from these dams were fed a milk replacer (MR) with either low (LLA) or high linoleic acid (HLA) concentration as the sole feedstuff during the first 30 d. Liver biopsy was performed at 30 d of age, and microarray analysis was performed on 18 liver samples. Total concentration of FA in liver were greater in calves fed LLA compared with those fed HLA MR (8.2 vs. 7.1%), but plasma concentrations of total FA did not differ due to MR diets. The FA profiles of plasma and liver of calves were affected differently by the prepartum diets. Specifically, the FA profile in liver was affected moderately by the feeding of fat prepartum, but the profiles did not differ due to the type of FA fed prepartum. The type of MR fed during the first 30 d of life had major effects on both plasma and liver FA profiles, resembling the type of fat fed. Plasma and liver of calves fed LLA MR had greater percentage of medium-chain FA (C12:0 and C14:0), whereas plasma and liver from calves fed HLA MR had greater percentages of linoleic and α-linolenic acids. Dams fed fat or a specific type of FA modified the expression of some genes in liver of calves, particularly those genes involved in biological functions and pathways related to upregulation of lipid metabolism and downregulation of inflammatory responses. Feeding HLA instead of LLA MR modified the expression of hepatic genes, including genes predicted to decrease infections and to increase lipid utilization and protein synthesis. Research evaluating the effect of FA supplementation during uterine and neonatal life on the future productivity of the neonate is warranted.

Short communication: Initial evidence supporting existence of potential rumen epidermal stem and progenitor cells

The bovine rumen epidermis is a keratinized multilayered tissue that experiences persistent cell turnover. Because of this constant cell turnover, epidermal stem cells and their slightly more differentiated daughter cells, epidermal progenitor cells, must exist in the stratum basale of rumen epidermis. To date, these 2 epidermal cell populations and any unique cellular markers they may possess remain completely uncharacterized in the bovine rumen. An important first step in this new research area is the demonstration of the relative abundance and existence of markers for these cells in rumen tissue. A related second step is to document rumen epidermal proliferative responses to an extrinsic signal such as nutrient concentration within the rumen. The objectives of this experiment were to evaluate the extrinsic effect of diet on (1) gene expression of 6 potential rumen epidermal stem or progenitor cell markers and (2) rumen epidermal cell proliferation within the stratum basale. Twelve preweaned Holstein heifers were fed either a restricted diet (R) or an enhanced diet (EH). Animals on R received a milk replacer (MR) diet fed at 0.44kg of powder dry matter (DM)/d (20.9% crude protein, 29.8% fat, DM basis) and EH received MR at 1.08kg of powder dry matter/d (28.9% crude protein, 26.2% fat, DM basis). All calves had access to a 20% crude protein starter and were weaned during wk 7 of the experiment. Lifetime DM intake was 0.73kg of DM/calf per day for R (5.88 Mcal of net energy/calf per day) and 1.26kg of DM/calf per day for EH (10.68 Mcal of net energy/calf per day). Twenty-four hours before slaughter heifers received an intravenous dose of 5-bromo-2′-deoxyuridine to label proliferating cells. Heifers were slaughtered at 8 wk of age, and rumen samples from the ventral sac region were obtained and stored in RNA preservative and processed for routine histology. Quantitative real-time reverse transcriptase PCR was used to analyze relative abundance of genes. Candidate genes for markers of epidermal stem and progenitor cells were β1-integrin (ITGB1), tumor protein p63 (TP63), keratin-14 (KRT14), Notch-1 (NOTCH1), Leu-rich repeat-containing G protein-coupled receptor 5-expressing (LGR5), and musashi-1 (MSI1). All genes were detected in the rumen tissue; ITGB1 was increased in EH compared with R. 5-Bromo-2′-deoxyuridine immunohistochemistry revealed that both R and EH rumen tissue had proliferating cells within the stratum basale of the rumen epidermis at the time of analysis. The EH diet resulted in an additive effect on cell proliferation. The percentage of cells in the stratum basale synthesizing DNA in preparation for mitosis nearly doubled (23.8±2.4% for EH vs. 14.7±2.0% for R) compared with calves fed R. This work represents the first attempt at characterizing rumen epidermal stem and progenitor cells. We demonstrated the relative abundance and existence of potential markers in rumen tissue and showed a rumen epidermal proliferative response to the extrinsic stimulus of nutrient concentration in the form of diet.

Supplementation of pre-weaning diet with l-arginine has carry-over effect to improve intestinal development in young piglets

This study tested the hypothesis that pre-weaning supplemental arginine may have a carry-over effect on intestinal growth and development of piglets immediately after weaning. Fifty-four [Duroc × (Landrace × Yorkshire)] piglets were fed a milk replacer diet supplemented with 0 (control), 4, or 8 g kg−1 of l-arginine from d 4 to 21 of age (6 replicate pens of 3 piglets per group). Piglets were then weaned to a common corn–soybean meal diet and fed for another 21 d. On day 42, 6 pigs per treatment were randomly selected for blood and tissue sampling. Arginine supplementation improved body weight of the piglets on d 42, average daily gain during d 22–31 (P &lt; 0.05). Supplementation of 8 g kg−1 arginine decreased feed:gain (F:G) ratio in piglets during d 22–31 (P = 0.010). Compared with controls, 8 g kg−1 arginine improved villous height in duodenum, jejunum, and ileum; villous area in duodenum and jejunum; relative intestine weight; and plasma contents of insulin at d 42 (P &lt; 0.05). Arginine supplementation increased mucosal protein content in all 3 segments of the small intestine (P &lt; 0.05). These novel results clearly demonstrate a carry-over effect of pre-weaning supplementation with arginine on enhanced intestinal growth and development in the early post-weaning period.

Growth, intake, and health of Holstein heifer calves fed an enhanced preweaning diet with or without postweaning exogenous estrogen

Research has shown that changes in nutrition both before and after weaning can affect mammary development. Additionally, estrogen is known to be a potent mammogenic stimulant. Our objectives were to determine effects of altered preweaning feeding and exogenous estradiol postweaning on growth, intake, and health. Thirty-six Holstein heifer calves were reared on (1) a restricted milk replacer (MR) diet fed at 0.44kg powder dry matter (DM)/day [R; 20.9% crude protein (CP), 19.8% fat, DM basis], or (2) an enhanced MR fed at 1.08kg powder DM/d (EH; 28.9% CP, 26.2% fat, DM basis). The MR feeding was reduced 50% during wk 8 to prepare for weaning. Starter was offered after wk 4 but balanced between treatments. Body weight and frame were measured weekly with intakes and health monitored daily. At weaning, a subset of calves were slaughtered (n=6/diet). Enhanced-fed calves had greater carcass, thymus, liver, spleen, and mammary gland (parenchyma and mammary fat pad) weights. The EH calves also had greater average daily gain (ADG) starting during wk 1 (0.36 vs. −0.06kg/d) and lasting through wk 7 (1.00 vs. 0.41kg/d). Remaining calves received estrogen implants or placebo and were slaughtered at the end of wk 10, creating 4 treatments: (1) R, (2) R + estrogen (R-E2), (3) EH, and (4) EH + estrogen (EH-E2). Postweaning ADG was similar between R, EH, and EH-E2 calves, but greater in R-E2 calves than E calves. The EH-E2 calves had the heaviest mammary glands, and R-E2 calves had heavier mammary glands than R calves. The EH calves consumed more MR DM, CP, and fat preweaning. The R-fed calves consumed more starter DM preweaning. Fecal score was greater for EH calves (1.74 vs. 1.50) preweaning, but days medicated did not differ. Fecal scores were lower for R-E2 calves postweaning. Improved preweaning feeding of calves increased body weights and frame measures. Differences in body weights remained postweaning. Enhanced-fed calves showed greater ADG during the preweaning period but not postweaning. Exogenous estrogen may elicit diet-dependent growth responses. Analysis of collected samples will allow determination of cellular and molecular processes responsible for the marked differences in mammary development observed.

Veal Calves Produce Less Antibodies against C. Perfringens Alpha Toxin Compared to Beef Calves.

Enterotoxaemia is a disease with a high associated mortality rate, affecting beef and veal calves worldwide, caused by C. perfringens alpha toxin and perfringolysin. A longitudinal study was conducted to determine the dynamics of antibodies against these toxins in 528 calves on 4 beef and 15 veal farms. The second study aimed to determine the effect of solid feed intake on the production of antibodies against alpha toxin and perfringolysin. The control group only received milk replacer, whereas in the test group solid feed was provided. Maternal antibodies for alpha toxin were present in 45% of the veal calves and 66% of the beef calves. In beef calves a fluent transition from maternal to active immunity was observed for alpha toxin, whereas almost no veal calves developed active immunity. Perfringolysin antibodies significantly declined both in veal and beef calves. In the second study all calves were seropositive for alpha toxin throughout the experiment and solid feed intake did not alter the dynamics of alpha and perfringolysin antibodies. In conclusion, the present study showed that veal calves on a traditional milk replacer diet had significantly lower alpha toxin antibodies compared to beef calves in the risk period for enterotoxaemia, whereas no differences were noticed for perfringolysin.

Effects of milk replacer and starter diet provided as creep feed for suckling pigs on pre- and post-weaning growth.

This study was aimed at investigating the long-term effects of provision of liquid milk replacer (MR) and solid starter diet (SD) during lactation on post-weaning (PW) growth of pigs. In experiment 1, 33 cross-bred litters were allotted to four treatments: no supplement (CON), MR ad libitum, SD ad libitum and 100 g SD/litter/day from lactation day 4 through weaning at day 21 during late fall. In experiment 2, 40 litters received MR or none in July. PW pigs received commercial diets to marketing. In experiment 1, weaning weight (WW), pre-weaning average daily gain (ADG) and mortality (2.4%) were not influenced by creep-feeding MR or SD. ADG was greater (P < 0.05) in the MR group versus CON during days 21-54, but did not differ across the treatments during days 54-162. In experiment 2, ADG during lactation and WW were greater in the MR group versus CON, with mortality lower in the former (5.6 vs. 10.3%). However, PW ADG to day 175 did not differ between the two groups. Results suggest that creep-feeding MR or SD has no effect on PW growth. However, it remains possible that MR reduces PW mortality during the hot season.

A neonatal piglet model for investigating brain and cognitive development in small for gestational age human infants.

The piglet was investigated as a potential model for studying brain and cognitive deficits associated with being born small for gestational age (SGA). Naturally farrowed SGA (0.7–1.0 kg BW) and average for gestational age (AGA, 1.3–1.6 kg BW) piglets were obtained on postnatal day (PD) 2, placed in individual cages, and provided a nutritionally adequate milk replacer diet (285 ml/kg/d). Beginning at PD14, performance in a spatial T-maze task was assessed. At PD28, piglets were anesthetized for magnetic resonance (MR) imaging to assess brain structure (voxel-based morphometry), connectivity (diffusion-tensor imaging) and metabolites in the hippocampus and corpus callosum (proton MR spectroscopy). Piglets born SGA showed compensatory growth such that BW of SGA and AGA piglets was similar (P>0.05), by PD15. Birth weight affected maze performance, with SGA piglets taking longer to reach criterion than AGA piglets (p<0.01). Total brain volume of SGA and AGA piglets was similar (P<0.05), but overall, SGA piglets had less gray matter than AGA piglets (p<0.01) and tended to have a smaller internal capsule (p = 0.07). Group comparisons between SGA and AGA piglets defined 9 areas (≥ 20 clusters) where SGA piglets had less white matter (p<0.01); 2 areas where SGA piglets had more white matter (p<0.01); and 3 areas where SGA piglets had more gray matter (p<0.01). The impact of being born SGA on white matter was supported by a lower (p<0.04) fractional anisotropy value for SGA piglets, suggesting reduced white matter development and connectivity. None of the metabolites measured were different between groups. Collectively, the results show that SGA piglets have spatial learning deficits and abnormal development of white matter. As learning deficits and abnormalities in white matter are common in SGA human infants, the piglet is a tractable translational model that can be used to investigate SGA-associated cognitive deficits and potential interventions.

Effect of milk replacer feeding program on performance of Belgian Blue double-muscled rearing calves

Abstract. One hundred and four Belgian Blue double-muscled calves were divided into four groups to examine the effects of different milk replacer (MR) programs. Calves in treatment group 1 received a MR diet reconstituted at 125 g/l, fed at 10 % of their initial live weight in two meals daily. Weaning occurred abruptly at a concentrate intake of 0.5 kg/d. Treatment 2 was similar to treatment 1, except that weaning occurred at a concentrate intake of 0.75 kg/d. Treatment 3 was similar to treatment 2, except that MR was fed once daily at 5 % of initial body weight from a concentrate intake of 0.5 kg/d onwards. Treatment 4 was similar to treatment 3, except that MR at a concentration of 200 g/l was fed once daily from the third week until a concentrate intake of 0.5 kg/d. Similar concentrates and grass hay were fed. Pre-weaning gain averaged 0.51, 0.57, 0.56 and 0.53 kg/d, respectively (P &lt; 0.05; SEM: 0.01). Daily nutrient intake was lowest for treatment 1. No effect on diarrhoea was found. Post-weaning gain did not differ among treatments. Daily gain during the whole rearing period (20 weeks) averaged 0.83 kg and was not affected by treatment. Calves assigned to treatment 1 had a lower daily intake of MR, while feed efficiency tended to be worse. Weaning can be successfully accelerated by skipping over a meal when concentrate intake exceeded 0.5 kg/d, or by combining one MR meal daily with an increased concentration of 200 g/l from an age of three weeks onwards.

Utilization of milk minerals by Iberian suckling piglets

Little information is available concerning mineral metabolism in suckling piglets. The utilization of milk minerals and the mineral composition of Iberian (IB) suckling piglets were studied in two consecutive experiments at different ambient temperatures (trial 1, 27 ± 2°C; trial 2, 22 ± 2°C). Milk composition and the piglets’ performance were determined weekly over a 34 days lactation period and, at the end, body mineral contents were analyzed and mineral retention and bioavailability were calculated. The ash content in IB sows’ milk and in suckling IB piglets was found to be higher than that reported for lean genotypes. During lactation, mean ash content per unit of body weight gain in IB piglets (40.6 g kg-1) was 42% higher than that observed for lean breeds, and weaned IB piglets contained 60% more Ca (11-12.7 g kg-1 empty body weight) and P (7-7.5 g kg-1 empty body weight), compared with conventional pigs. Minerals from milk were retained by the IB piglet with an overall efficiency of 78.3%, 66.3% and 48.7% for Ca, P and Mg, respectively. Significant differences between trials were observed in the mineral fraction composition of the milk, which were reflected in piglet body composition at weaning, presumably due to differences in ambient temperature. Present findings underline genotype differences in mineral composition of sow’s milk and suckling piglets and may provide a useful starting point for formulating milk-replacer diets for IB piglets.

Neonatal Calf Infection with Respiratory Syncytial Virus: Drawing Parallels to the Disease in Human Infants

Respiratory syncytial virus (RSV) is the most common viral cause of childhood acute lower respiratory tract infections. It is estimated that RSV infections result in more than 100,000 deaths annually worldwide. Bovine RSV is a cause of enzootic pneumonia in young dairy calves and summer pneumonia in nursing beef calves. Furthermore, bovine RSV plays a significant role in bovine respiratory disease complex, the most prevalent cause of morbidity and mortality among feedlot cattle. Infection of calves with bovine RSV shares features in common with RSV infection in children, such as an age-dependent susceptibility. In addition, comparable microscopic lesions consisting of bronchiolar neutrophilic infiltrates, epithelial cell necrosis, and syncytial cell formation are observed. Further, our studies have shown an upregulation of pro-inflammatory mediators in RSV-infected calves, including IL-12p40 and CXCL8 (IL-8). This finding is consistent with increased levels of IL-8 observed in children with RSV bronchiolitis. Since rodents lack IL-8, neonatal calves can be useful for studies of IL-8 regulation in response to RSV infection. We have recently found that vitamin D in milk replacer diets can be manipulated to produce calves differing in circulating 25-hydroxyvitamin D3. The results to date indicate that although the vitamin D intracrine pathway is activated during RSV infection, pro-inflammatory mediators frequently inhibited by the vitamin D intacrine pathway in vitro are, in fact, upregulated or unaffected in lungs of infected calves. This review will summarize available data that provide parallels between bovine RSV infection in neonatal calves and human RSV in infants.

Differential Expression of Cytokines in Response to Respiratory Syncytial Virus Infection of Calves with High or Low Circulating 25-Hydroxyvitamin D3

Deficiency of serum levels of 25-hydroxyvitamin D3 has been related to increased risk of lower respiratory tract infections in children. Respiratory syncytial virus (RSV) is a leading cause of low respiratory tract infections in infants and young children. The neonatal calf model of RSV infection shares many features in common with RSV infection in infants and children. In the present study, we hypothesized that calves with low circulating levels of 25-hydroxyvitamin D3 (25(OH)D3) would be more susceptible to RSV infection than calves with high circulating levels of 25(OH)D3. Calves were fed milk replacer diets with different levels of vitamin D for a 10 wk period to establish two treatment groups, one with high (177 ng/ml) and one with low (32.5 ng/ml) circulating 25(OH)D3. Animals were experimentally infected via aerosol challenge with RSV. Data on circulating 25(OH)D3 levels showed that high and low concentrations of 25(OH)D3 were maintained during infection. At necropsy, lung lesions due to RSV were similar in the two vitamin D treatment groups. We show for the first time that RSV infection activates the vitamin D intracrine pathway in the inflamed lung. Importantly, however, we observed that cytokines frequently inhibited by this pathway in vitro are, in fact, either significantly upregulated (IL-12p40) or unaffected (IFN-γ) in the lungs of RSV-infected calves with high circulating levels of 25(OH)D3. Our data indicate that while vitamin D does have an immunomodulatory role during RSV infection, there was no significant impact on pathogenesis during the early phases of RSV infection. Further examination of the potential effects of vitamin D status on RSV disease resolution will require longer-term studies with immunologically sufficient and deficient vitamin D levels.