Effects of dietary clays on performance and intestinal mucus barrier of broiler chicks challenged with Salmonella enterica serovar Typhimurium and on goblet cell function in vitro.

In vivo and in vitro experiments were conducted to test for beneficial effects of dietary clays on broiler chicks challenged with Salmonella enterica serovar Typhimurium and to explore potential mechanisms. First, two hundred forty 1-d-old male broilers (initial BW: 41.6 ± 0.4 g) were allotted in a 2 × 4 factorial arrangement in a randomized complete block design. There were 2 infection treatments (with or without Salmonella) and 4 diets: basal (BAS), 0.3% smectite A (SMA), 0.3% smectite B, and 0.3% zeolite. The Salmonella reduced (P < 0.05) the growth rate of chicks fed the BAS, and feeding clay largely restored it (challenge × diet interaction, P < 0.05). Goblet cell number and size were increased (P < 0.05) by Salmonella in chicks fed the BAS and were reduced (P < 0.05) in Salmonella-challenged chicks by feeding SMA. Villus height was reduced by the Salmonella challenge in the chicks fed dietary clays (P < 0.01) but not in chicks fed the BAS (interaction P < 0.05). A human adenocarcinoma cell line (LS174T) was cultured in vitro in 3 separate experiments in the absence or presence of 3 concentrations (0.05, 0.10, and 0.50%) of SMA. Expression of mucin 2 (MUC2), resistin-like molecule ß (RELMß), and trefoil factor 3 (TFF3) were determined by real-time reverse-transcription PCR. The expression of RELMß was increased and expression of MUC2 was reduced (P < 0.05) by 0.10% SMA. Also, LS174T cells were cultured without or with SMA (0.05 and 0.10%) and the medium and cell lysate were analyzed for RELMß using an immunoblot assay. Protein expression of RELMß in the cell lysate was reduced (P < 0.05) by SMA addition but increased in the medium, indicating that SMA increased secretion of RELMß, thus depleting the cell and concentrating this protein in the medium. In conclusion, the dietary clays restored the growth depression caused by Salmonella, and changes in goblet cell function may contribute to the benefits of one of the clays, specifically SMA.

Effect of corn distillers dried grains with solubles and Eimeria acervulina infection on growth performance and the intestinal microbiota of young chicks.

Chicks were used to determine whether dietary corn distillers dried grains with solubles (DDGS) may prevent or ameliorate Eimeria acervulina (EA) infection. The experiment had a completely randomized design with a factorial arrangement of 3 diets (inclusion of 0, 10, or 20% DDGS) × 2 challenge treatments: inoculation with distilled water or with 10(6) sporulated EA oocysts. Each treatment was replicated with 8 pens of 5 chicks each. Experimental diets were fed from 7 to 21 d of age. Inoculation occurred on d 10 of age, considered postinoculation (PI) d 0. Feed intake and BW were measured on PI d 0, 7, and 14. Excreta samples were collected on PI d 0, 5 to 10, 12, and 14 to detect oocysts. On PI d 14, mucosal samples were collected for the analysis of bacterial populations by denaturing gradient gel electrophoresis, using the V3 region of bacterial 16S ribosome. The EA challenge reduced (P < 0.001) ADG by 17%, ADFI by 12%, and G:F by 6% from PI d 0 to 7, and by smaller percentages from PI d 7 to 14. Diet and challenge treatments did not interact in the chick performance, so dietary DDGS did not alleviate EA infection. Oocysts in excreta were detected PI only in EA chicks and no dietary effects were found. Cecal bacterial population was changed (P < 0.05) by effect of dietary DDGS and EA infection. The cecal bacterial diversity among chicks within treatments and homogeneity among chicks within treatments were reduced by EA infection (P = 0.02 to 0.001) and increased by feeding 10% DDGS (diet quadratic, P < 0.001). In summary, feeding up to 20% DDGS to young chicks did not prevent or ameliorate EA infection. Changes in cecal microbiota of chicks fed 10% DDGS can be interpreted as beneficial for intestinal health.

Mycotoxin-contaminated diets and an adsorbent affect the performance of Nellore bulls finished in feedlots.

Mycotoxins are present in almost all feedstuffs used in animal nutrition but are often ignored in beef cattle systems, even though they can affect animal performance. The objective of this study was to evaluate the effects of mycotoxins and a mycotoxin adsorbent (ADS) on performance of Nellore cattle finished in a feedlot. One hundred Nellore cattle (430 ± 13 kg) were used in a randomized complete block design with a 2 × 2 factorial arrangement of treatments. The factors consisted of two diets with either natural contamination (NC) or exogenous contamination (EC) and the presence (1 g/kg of DM; ADS) or absence of a mycotoxin adsorbent. The NC and EC diets had the following contaminations, respectively: 0.00 and 10.0 µg/kg aflatoxins, 5114 and 5754 µg/kg fumonisins, 0.00 and 42.1 µg/kg trichothecenes B, 0.00 and 22.1 µg/kg trichothecenes A and 42.9 and 42.9 µg/kg fusaric acid. At the beginning of the experiment, all animals were weighed, and four randomly selected animals were slaughtered to evaluate the initial carcass weight. After 97 days of treatment, all animals were weighed and slaughtered. There was no interaction among factors for the DM intake (DMI; P = 0.92); however, there was a tendency for the EC diets to decrease the DMI by 650 g/day compared to animals fed NC diets (P = 0.09). There was a trend for interaction among factors (P = 0.08) for the average daily gain (ADG), where the greatest ADG was observed for cattle fed the NC diet (1.77 kg), and the lowest was observed for those fed the EC diet (1.51 kg). The NC + ADS and EC + ADS treatments presented intermediate values for ADG. The animals fed the NC diet had a greater final BW (596 kg) than animals fed the EC treatment (582 kg; P = 0.04). There was a tendency for interaction among factors for carcass gain (P = 0.08). Similarly to ADG, the highest carcass gain was observed for animals fed the NC diet (1.20 kg), and the lowest was observed for those fed the EC diet (1.05 kg). The NC + ADS and EC + ADS treatments presented intermediate values. The natural contamination groups had greater carcass gain than that of the EC groups, and the use of the ADS recovered part of the weight gain in animals fed the EC diet. In conclusion, mycotoxins at the levels evaluated affected the performance of beef cattle, and adsorbents may mitigate their impact.

Standardized amino acid digestibility in cecectomized roosters and lysine bioavailability in chicks fed distillers dried grains with solubles.

This study was conducted to compare the concentration of standardized digestible (SDD) Lys and relative bioavailable Lys in 7 sources of corn distillers dried grains with solubles (DDGS). A second objective was to evaluate 2 in vitro methods, reactive Lys and color score, to predict the concentration of SDD Lys and bioavailable Lys in DDGS. Seven sources of DDGS were fed to cecectomized roosters, and digestibility of amino acids was measured using the total excreta collection method. To measure the relative bioavailable Lys in DDGS, a standard curve (r(2) = 0.96, P < 0.01) was constructed from 9-d weight gain of young chicks fed a Lys-deficient basal diet or diets containing increasing concentrations of l-Lys-HCl. Seven additional diets were formulated by adding each of the 7 sources of DDGS to the basal diet, and total weight gain of chicks was measured. Weight gain of chicks fed each DDGS-containing diet was then compared with the standard curve to calculate the bioavailable Lys and bioavailability of Lys in each source of DDGS. All DDGS sources were analyzed for reactive Lys using the guanidination procedure, and a Hunterlab color score was used to measure the degree of lightness (L), redness (a), and yellowness (b). Results showed that the mean SDD Lys values and the mean relative bioavailability of Lys were 61.4 and 69.0%, respectively. Differences between the concentration of SDD Lys and the concentration of bio-available Lys were not observed in 5 of 7 sources of DDGS. The concentration of SDD Lys was correlated (r(2) = 0.84, P < 0.05) with the concentration of reactive Lys in DDGS. Greater Hunterlab L scores were associated with a greater (r(2) = 0.90, P < 0.05) concentration of bioavailable Lys in DDGS. In conclusion, the concentration of SDD Lys in DDGS does not overestimate the concentration of bioavailable Lys for poultry. Values for reactive Lys may be used to estimate the concentration of SDD Lys, whereas Hunterlab L may be used to estimate the concentration of bioavailable Lys in DDGS.

Do mycotoxin contaminated diets and yeast cell wall adsorbent affect meat quality of Nellore bulls finished in feedlot? - A short communication.

Ninety-six Nellore bulls (430 ±â€¯13 kg and 24 months) were assigned to a completely randomized block design (2 × 2 factorial arrangement of treatments) to evaluate meat quality. Dietary treatments consisted of natural or exogenous contamination with mycotoxins (Factor 1), with or without yeast cell wall adsorbent (10 g/animal/d; Factor 2). The diets were provided during 97 d. The meat chemical composition was unaffected (P ≥ .37) by the factors and the averages of variables were 74.2% moisture, 22.7% protein, 1.04% ether extract, and 2.10% ash. The L*, a*, b*, E*, C* (P ≥ .11), cooking loss (P ≥ .24) and Warner-Bratzler shear force (P ≥ .17) were also similar among factors. In conclusion, low mycotoxin contamination and yeast cell wall based adsorbent do not affect meat quality of Nellore bulls finished in feedlot.

Effects of dietary soybean meal concentration on growth and immune response of pigs infected with porcine reproductive and respiratory syndrome virus.

An experiment was conducted to determine the effects of dietary soybean meal (SBM) concentration on the growth performance and immune response of pigs infected with porcine reproductive and respiratory syndrome virus (PRRSV). Four experimental treatments included a 2 × 2 factorial arrangement of 2 dietary SBM concentrations, 17.5% (LSBM) or 29% (HSBM), and 2 levels of PRRSV infection, uninfected sham or PRRSV infected. Sixty-four weanling pigs of split sex (21 d of age, 7.14 ± 0.54 kg) were individually housed in disease containment chambers. Pigs were provided a common diet for 1 wk postweaning before being equalized for BW and sex and allotted to 4 treatment groups with 16 replicate pigs per group. Pigs were fed experimental diets for 1 wk before receiving either a sham inoculation (sterile PBS) or a 1 × 10 50% tissue culture infective dose of PRRSV at 35 d of age (0 d postinoculation, DPI). Pig BW and feed intake were recorded weekly, and rectal temperatures were measured daily beginning on 0 DPI. Blood was collected on 0, 3, 7, and 14 DPI for determination of serum PRRSV load, differential complete blood cell counts, and haptoglobin and cytokine concentrations. Infection with PRRSV increased (P < 0.01) rectal temperatures of pigs throughout the infection period, with no influence of dietary SBM concentration. Pigs in the PRRSV-infected group had lower (P < 0.01) ADFI and G:F from 0 to 14 DPI compared with uninfected pigs. In the PRRSV-infected group, pigs fed HSBM tended to have improved ADG (P = 0.06) compared with pigs fed LSBM, whereas there was no influence of SBM concentration on growth of pigs in the uninfected group. At 14 DPI, PRRSV-infected pigs fed HSBM had a lower serum PRRSV load (P < 0.05), a higher (P = 0.02) hematocrit value, and a tendency for greater hemoglobin concentration (P = 0.09) compared with pigs fed LSBM. Serum haptoglobin and tumor necrosis factor-α concentrations of PRRSV-infected pigs were lower (P < 0.05) in pigs fed HSBM at 3 and 14 DPI, respectively, than in pigs fed LSBM. Overall, increasing the dietary SBM concentration modulated the immune response and tended to improve the growth of nursery pigs during a PRRSV infection.

Spray-dried plasma attenuates inflammation and improves pregnancy rate of mated female mice.

Three studies were conducted to test the hypothesis that dietary spray-dried plasma (SDP) might improve pregnancy rate by ameliorating inflammation, using mice in an experimental model that produces a low pregnancy rate. Mated female mice (C57BL/6 strain) were purchased and shipped from a vendor (Bar Harbor, ME) to the university facility (Urbana, IL) on the day the vaginal plug was found (gestation day [GD] 1), arriving at the laboratory on GD 3 after 2 d transport by air and ground. Mice (Exp. 1: n = 250, 16.0 ± 1.2 g BW; Exp. 2: n = 202, 16.2 ± 1.2 g BW; Exp. 3: n = 156, 16.4 ± 1.1 g BW) were housed in individual cages and randomly assigned to dietary treatments (Exp. 1: 0 [CON] and 8% SDP in the diet, ≥ 90 mice/diet; Exp. 2: 0, 1, 2, 4, and 8% SDP in the diet, ≥ 40 mice/diet; Exp. 3: 0, 1, and 8% SDP in the diet, 48 mice/diet) fed from arrival. In Exp. 1 and 2, pregnancy of each mouse was determined on GD 17 based on BW, shape of abdomen, and inspection postmortem, and maternal growth performance from GD 3 to 17 was measured. On GD 19, pregnant mice in Exp. 2 were euthanized to measure number of fetuses and fetal and placental weights. Pregnancy rates in CON were low in both Exp. 1 (11%) and Exp. 2 (7%). The SDP consistently and markedly increased (P < 0.05) pregnancy rates in both Exp. 1 (49%) and Exp. 2 (35-43%) compared with the CON. In Exp. 3, 12 randomly selected mice were euthanized immediately after they arrived as an initial group. From GD 4 to 7, randomly selected mice were also euthanized each day (12 mice/diet). After euthanasia, the abdominal cavity was opened to check pregnancy by uterine inspection and to collect blood and uterus samples for immune measurements. The SDP increased (P < 0.05; 40 vs. 15%) pregnancy rate compared with the CON. Concentrations of indicators of inflammation and stress (uterine TNF-α and IFN-γ, and serum TNF-α, C-reactive protein, and cortisol) were greatest (P < 0.05) and an anti-inflammatory cytokine (TGF-ß1) was lowest (P < 0.05) soon after arrival, on GD 3 or 4. The SDP decreased (P < 0.05) the uterine concentrations of TNF-α and IFN-γ, and serum TNF-α, C-reactive protein, and cortisol, compared with the CON, but increased (P < 0.05) the uterine concentration of TGF-ß1. In conclusion, dietary SDP improves the low pregnancy rates in this model, apparently by attenuating inflammation.

Influence of lactation length and feed intake on reproductive performance and blood concentrations of glucose, insulin and luteinizing hormone in primiparous sows.

Twenty-four pregnant gilts were assigned to four experimental treatments in a 2 x 2 factorial arrangement. The first factor was lactation length (12 vs. 21 days) (LL); the second factor was a provided amount of diet (FF, full feeding vs. low, 2 kg/day). The same diet (1% lysine and 3.27 Mcal ME/kg) was used from farrowing to 1 day after weaning. Sow body weight, backfat thickness (BF), litter weights, and blood samples were measured prior to and 1 day after weaning. Sows were monitored for estrous once daily in the presence of a boar until 35 days after weaning or until estrous was detected. Average feed intake during lactation (ADFI) was 1.9 (low) and 4.0 (FF) kg/day. ADFI among individual sows varied from 1.8 to 4.9 kg/day. Positive effects of both LL and feed intake treatments were found (P < 0.05) on sow body weight loss, backfat loss, glucose concentrations, mean luteinizing hormone (LH) concentrations, and LH pulse frequency prior to weaning, and farrowing-to-estrous interval. Greater concentrations of insulin prior to weaning were associated only with feed intake treatment (P < 0.05). No interactions between LL and feed intake treatments were found in any measures except for sow body weight loss. Using regression analysis, greater lactation feed intake was associated with greater concentrations of insulin and glucose, greater LH pulse frequency prior to weaning and shorter farrowing-to-estrous interval in both LL treatments. We suggest that greater feed intake during lactation improves farrowing-to-estrous interval through LH release regardless of LL treatment.

Protein nutrition of gestating sows.

Dietary amino acid requirements of gestating sows vary depending on genetic strain, energy intake, body weight, and other factors. Estimation of amino acid requirements for gestating sows in a defined situation should be directed toward achieving a high rate of protein accretion and a modest rate of fat accretion. More information is needed to set target accretion rates precisely. A simple mathematical model was developed with the limited objectives of 1) aiding in understanding the interactions among energy intake, amino acid intake, protein accretion potential, and body weight in affecting the amount of body protein and fat accreted by pregnant sows and 2) providing general guidelines for feeding programs. Predictions from the model suggest that the daily lysine requirement varies markedly with variation in ME intake but that the requirement as a percentage of the diet is more stable as ME intake varies. At moderate ME intake, the lysine requirement seems greater during late gestation than earlier. The lysine requirement of heavy sows is less than that of light gilts at a similar ME intake, and this offers opportunity for modest cost savings in pork production. A compromise is necessary between the goals of a high rate of protein accretion and a modest rate of fat accretion. It seems that a sow's potential protein accretion rate is rarely limiting.

Protein and fat utilization in lactating sows: I. Effects on milk production and body composition.

In order to provide data with which to challenge a model of metabolism of lactating sows, we conducted a study to determine milk production and body and mammary composition in sows consuming a range of energy and amino acid intakes and nursing 11 to 12 pigs. Sows (2nd through 4th parity) consumed the same ration during gestation and consumed 6.1 kg/d (as-fed) for a 20 d lactation. Litter size was standardized at 12 pigs within 3 d of farrowing. Diets were formulated to provide three different amounts of protein intake and two different amounts of fat intake. Protein intakes of sows in high (HP), medium (MP), and low protein (LP) treatment groups were 863, 767, and 678 g/d with 59, 53, and 47 g/d lysine at two levels of fat intake, 117 (LF) and 410 g/d (HF). Number of pigs weaned per litter was 11.4 +/- 0.5 and milk production and litter weight gain was less (P < 0.01) in the last week of lactation for sows consuming the least protein. Medium and low protein intakes increased (P < 0.05) loss of body lean and protein. Change in carcass protein during lactation was -1.4, -3.0, -2.2, -1.2, -1.9 and -2.1 kg (SD 2.6) for sows fed HPLF, MPLF, LPLF, HPHF, MPHF, and LPHF. Body fat (carcass and visceral) change was 0.4, -3.7, -4.1, -0.3, 3.4, and -1.3 kg (SD 6.6) in HPLF, MPLF, LPLF, HPHF, MPHF, and LPHF groups. Total amount of mammary parenchyma increased more (P < 0.05) in sows fed a higher fat diet. These data are consistent with general knowledge of changes in body composition in lactation of sows. However, changes in body protein and fat were correlated across treatments and different from that reported for sows nursing smaller litters. These data help our quantitative understanding of nutrient flux in sows nursing large litters and allow a severe challenge of existing models of metabolism in sows.

Protein and fat utilization in lactating sows: II. Challenging behavior of a model of metabolism.

The objective was to challenge the behavior of an existing mechanistic model of sow metabolism using data from a study that determined effects of fat and amino acid intakes on milk production, body and mammary composition in sows nursing 10 to 12 pigs. Sows were second through fourth parity; litter size was standardized at 12 pigs within 3 d of farrowing, and lactation was for 20 d. Diets were formulated and fed to provide three different amounts of protein intake and two different amounts of fat intake. Data were used to challenge the behavior of an existing mechanistic, deterministic, dynamic model for describing variation in milk production and changes in body composition. Nutrient intake and initial body weights and compositions were used as direct inputs into the model. The model could describe milk production within 1 SD of the mean on all rations. The model described body fat within 1 SD of observed values, but overestimated final body protein by approximately 30% (or between 1 and 2 SD). The model described the change in body fat and protein in response to 5% additional fat in the ration within 1 SD of observed (simulated - observed = -1.1 kg for protein and -0.7 for fat). The simulated response to dietary protein was within 1 SD (2.6 kg): simulated response from medium to high protein was 1.0 kg, observed 1.2; simulated response from medium to low was -0.7 kg, observed 0.3 kg. Thus, the model was not as accurate in describing the body protein response to a low-protein diet and overall, overestimated the retention of body protein. This model has utility for setting specific research hypotheses and may be amenable to use by nutritionists in a variety of applications. Further improvement in the ability of the model to describe metabolism and production of lactating sows is limited by a severe lack of data on metabolic interactions. Data on rates of muscle protein synthesis and proteolysis and interactions between amino acids, fatty acids, and glucose are needed to improve this and other models of sow production.

A mathematical integration of energy and amino acid metabolism of lactating sows.

A dynamic mathematical model of energy and protein metabolism of lactating sows is described in this article. The model is designed to contribute to a systematic and quantitative understanding of the biological connection between diet and reproduction. It traces the flow of energy-containing nutrients from absorption through intermediary metabolism, into and out of body stores, and into milk. State variables (pools) include lysine, other amino acids, glucose, fatty acids, acetate, propionate, acetyl-coenzyme A, ATP, oxygen, carbon dioxide, urea, lean-body protein, visceral protein, storage triacylglycerol, milk protein, milk triacylglycerol, and milk lactose. The rate of each transaction is a function of substrate and inhibitor concentrations, assuming saturable kinetics. Protein and fat turnover, substrate cycles, and the energy cost of membrane transport are explicitly considered. Dynamic simulation of a complete lactation is accomplished by iterating the numerical integration of 16 first-order, nonlinear differential equations, each associated with a pool. Most kinetic parameters were estimated indirectly. Preliminary tests suggest the model is sound. It promises to be useful as a research tool and, with further development, as a guide to practical feeding strategies.

Evaluation of a mathematical model of lactating sow metabolism.

A mathematical model of lactating sow metabolism was evaluated using three types of tests. First, 16 experimental treatments from four experiments reported in the literature were simulated with the model, and the simulated values for change in BW and protein and fat content were compared to reported or calculated values. Second, the model's response to level of feed intake, level of milk production, BW and composition at farrowing, and dietary lysine concentration was compared to expected responses. Third, the model's sensitivity to changes in several of its kinetic parameters was measured. There was good agreement between simulated and measured values for BW and fat loss and reasonable agreement for body protein loss. All responses to changes in external conditions were in expected directions and biologically reasonable. The model seemed rather robust with respect to changes in the kinetic parameters considered, although important changes in simulated values were found in some cases. Overall, the model seems sound. It can be useful in evaluation of feeding programs and in understanding biological relationships.

Feed intake pattern during lactation and subsequent reproductive performance of sows.

Daily feed intake during lactation was recorded for 20,296 lactating sows on 30 commercial farms in the United States. Each lactation feed record was categorized into one of six patterns: RAPID, rapid increase in feed intake; MAJOR, major drop; MINOR, minor drop; LLL, low feed intake throughout lactation; LHH, low intake during the 1st wk then an increase in feed intake for the remainder of lactation; and GRADUAL, gradual increase. A database containing 24,340 farrowing records and 19,015 subsequent litter records were abstracted from the PigCHAMP data files of the farms enrolled in the study. Multiple regression analyses revealed that ADFI during lactation had nonlinear or linear associations with weaning-to-first service interval (WSI), weaning-to-conception interval (WCI), litter weight at weaning (WWT), and subsequent litter size (SLS). Sows having LLL and LHH had longer (P < .01) WSI and WCI than the other patterns. Sows with MAJOR had a longer WCI (P < .05) than females with RAPID. Further, sows having MAJOR had lighter (P < .01) WWT than those with RAPID, MINOR, and GRADUAL. Sows having MAJOR had a higher (P < .01) proportion of females culled for anestrus relative to RAPID. Furthermore, sows exhibiting a drop in feed intake in either wk 1 or 2 were more likely to be culled for anestrus than sows having no drop. These results suggest that both the amount and pattern of feed intake during lactation influence subsequent reproductive performance.

Effects of supplemental biotin during gestation and lactation on reproductive performance of sows: a cooperative study.

A cooperative experiment to evaluate biotin addition to sow diets was conducted at three research stations using 303 litters. Primiparous and multiparous sows (overall average parity 2.8) were fed a 14% CP corn-soybean meal diet (140 micrograms/kg biotin), with or without supplemental biotin (330 micrograms added biotin per kg feed), throughout gestation and lactation. As many sows as possible were fed their respective diets through three successive parities. During gestation, sows were given from 1.82 to 2.27 kg of feed per day, depending on environmental conditions; during lactation sows had ad libitum access to feed. Supplemental biotin had no effect (P greater than .35) on sow weights at breeding, at d 109 of gestation, at farrowing or at weaning. No differences were found in litter size at birth (P greater than .18), but at d 21 of lactation, sows fed the diet containing supplemental biotin had larger litters than sows fed the unsupplemented diet (9.4 vs 8.7 pigs, respectively; P = .01). Pig weights at birth and d 21 of lactation were not affected (P greater than .20) by dietary treatment. Biotin supplementation did not affect (P greater than .28) the length of the interval from weaning to estrus. No evidence was found that feet cracks or bruises were reduced by biotin supplementation. The results indicate that biotin supplementation of a corn-soybean meal diet during gestation and lactation increased the number of pigs at d 21 of lactation, but it did not decrease the incidence of foot lesions.

Response of maternal-line sows to dietary protein concentration during lactation.

One hundred eighty-one maternal-line (Yorkshire x Landrace x Chester White or purebred Landrace) sows were used to determine effects of dietary protein concentration during lactation on voluntary feed intake of sows and sow and litter performance. Throughout gestation, sows received 1.8 kg/d of a 14% CP corn-soybean meal diet. Sows were assigned to dietary treatments based on parity (range = 1 to 9) and expected farrowing date. Treatments were corn-soybean meal diets that contained 13.6 (Low, L), 15.5 (Medium, M), 17.5 (High, H), or 19.2 (Very High, VH) % CP. Calculated lysine content of diets was .62 (L), .76 (M), .90 (H), and 1.05 (VH) %. Sows had ad libitum access to their assigned diets from the day of parturition until weaning (24.6 +/- .46 d postpartum). Pigs were cross-fostered irrespective of dietary treatment until d 3 postpartum. Diet had a cubic effect (P < .05) on the lactational weight change of sows (L, -9.1; M, -2.1; H, -4.6; VH, .8 kg; SE = 1.57) but had no effect on change in backfat depth during lactation or on voluntary feed intake of lactating sows (x = 6.0 kg/d). Litter size at weaning (9.6 +/- .17 pigs) was similar across dietary treatments; however, diet linearly affected (P < .05) daily litter weight gain (L, 2.01; M, 2.12; H, 2.18; VH, 2.14 kg; SE = .05). Postweaning interval to estrus averaged 5.2 +/- .25 d and was unaffected by dietary treatments. Our data suggest that dietary protein concentrations between 13.6 and 19.2% do not influence voluntary feed intake of lactating sows or weaning-to-estrus interval.(ABSTRACT TRUNCATED AT 250 WORDS)

Lactational and subsequent reproductive responses of lactating sows to dietary lysine (protein) concentration.

Gilts (n = 208) were used to evaluate the effect of lysine (protein) intake over three parities on lactation and subsequent reproductive performance. Sows were assigned randomly to one of five experimental diets at each farrowing. The five corn-soybean mealbased lactation diets contained increasing concentrations of total lysine (.60, .85, 1.10, 1.35, and 1.60%) and CP (14.67, 18.15, 21.60, 25.26, and 28.82%). Other amino acids were provided at a minimum of 105% of the NRC (1988) ratio to the lysine requirement. Sows had ad libitum access to their assigned diets from parturition until weaning (19.5+/-.2 d postpartum). All sows were fed a common gestation diet (14% CP and .68% lysine) from weaning to next farrowing. Litter size was standardized by d 3 postpartum to 10 pigs in parity 1 and 11 pigs in parity 2 and 3. Increasing dietary lysine (protein) linearly decreased (P<.05) voluntary feed intake of parity 1 (from 5.4 to 4.6 kg/d), 2 (from 6.5 to 5.8 kg/d), and 3 sows (from 6.8 to 6.2 kg/d). With the increase of dietary lysine (protein) concentration during lactation, litter weight gain responded quadratically (P<.05) in all three parities. Maximal litter ADG was 2.06, 2.36, and 2.49 kg/d in parities 1, 2, and 3, respectively, which occurred at about 44, 55, and 56 g/d of lysine intake for parity 1, 2, and 3 sows, respectively. Increasing dietary lysine (protein) had no effect (P>.1) on sow weight change, weaning-to-estrus interval, and farrowing rate in all three parities and no effect on backfat change in parity 2 and 3, but tended to increase backfat loss linearly (P<.1) in parity 1. A linear decrease of second litter size (total born, from 11.7 to 10.1, P<.1; born alive, from 11.0 to 8.9, P<.01) was observed when dietary lysine (protein) increased during the first lactation. Lysine (protein) intake during the second lactation had a quadratic effect on third litter size (P<.05; total born: 13.3, 11.2, 11.6, 11.9, and 13.6; born alive: 11.8, 10.1, 10.3, 11.2, and 12.4). However, fourth litter size was not influenced by lysine (protein) intake during the third lactation. These results suggest that the lysine (protein) requirement for subsequent reproduction is not higher than that for milk production. Parity influences the lysine (protein) requirement for lactating sows and the response of subsequent litter size to previous lactation lysine (protein) intake.

Response of growing-finishing pigs to decreasing floor space allowance and(or) virginiamycin in diet.

Five hundred forty crossbred pigs were utilized in four trials (10 replications) at two stations to determine the separate and interacting effects of decreasing floor space allowance with or without the addition of virginiamycin to the diet on performance of growing-finishing pigs. Pigs were allowed .37, .33 or .28 m2/pig during the growing phase (23 to 55 kg) and .74, .66, .56 m2/pig during the finishing phase (55 to 100 kg) and fed either a corn-soybean meal control diet or the control diet plus 11 mg of virginiamycin/kg of diet. Floor space allowances were achieved by varying pen size, so the number of pigs and feeder space per pig were constant for all pens. During the growing phase, daily gain (P less than .01) daily feed intake (P less than .05) and feed conversion ratio (P less than .05) decreased as floor space allowance decreased. During the finishing phase and for the total test period, daily gain (P less than .01) and feed conversion ratio (P less than .05) were reduced but daily feed intake was not affected (P greater than .05) by restricted floor space allowance. The addition of virginiamycin to the diet had no effect on pig performance. The virginiamycin X floor space allowance interaction was not significant, suggesting that pigs fed a diet with or without virginiamycin responded similarly to restricted floor space allowance. The data suggest that the addition of virginiamycin to the diet was ineffective in overcoming the decrease in performance of growing-finishing pigs caused by crowded conditions.

Effect of age, weaning and diet on digestive enzyme levels in the piglet.

Thirty-seven pigs were used to evaluate the effects of age and weaning on the level of protease in the gastric mucosa and trypsin, chymotrypsin, amylase and lipase in the pancreas. There was a positive allometry of the pancreas and gastric mucosa associated with age and with weaning to a solid diet. Increases with age in total activity of chymotrypsin, trypsin, amylase and gastric proteases were due to increases in both tissue weight and enzyme activity per gram of tissue. A general depression in pancreatic enzymatic activities, but not in gastric proteolytic activity, was found during the first week following weaning. Forty pigs were used in a second trial to evaluate the effects of age and weaning diet on the same digestive enzymes. Total activity of all enzymes assayed increased with time postweaning. Increases in total activity of lipase and chymotrypsin were due primarily to increased pancreatic weight postweaning. Amylase, trypsin and gastric protease increases were due both to increased tissue weight and increased activity per gram of tissue. There were no effects of diet on the weight of gastric mucosa or the level of activity of the gastric proteases. Pigs fed a diet containing 20% whey had larger pancreases (P less than .10) at slaughter and a greater, but nonsignificant, mean activity per gram of pancreas for all pancreatic enzymes. It appears that the pig has sufficient pancreatic and gastric enzyme activity so that performance should not be limited, with the possible exception of the period shortly after weaning. However diet digestibility and subsequent pig performance may be more directly related to the extent of release of these enzymes into the intestine and the conditions that exist therein.

Integration of factors affecting sow efficiency: a modeling approach.

A dynamic, partially stochastic mathematical model describing the reproductive performance of a sow herd is presented. The model stimulates a herd that averages 17.27 sow days/pig produced, with a mean of 9.06 pigs weaned/litter and 2.327 litters produced/sow each year. Several alternative options are simulated. Of these, the ones that increase the litter size at weaning appear most beneficial in terms of both biological and economic efficiencies.