The effects of parity and litter size on bone metabolic activity in pregnant and lactating sows

During gestation and lactation, female mammals often mobilize endogenous nutrient reserves to meet the resource demands of offspring production. These mobilized stores include calcium, phosphorous and other minerals that are resorbed from maternal bone to facilitate rapid mineralization of offspring bones. The extent to which bone mineral is resorbed is governed by the total amount of mineral taken in from the diet, but also by the competing demands of offspring and the minimum level of bone density that a female must sustain to support self-maintenance. The maximum amount of bone that a female may mobilize is undoubtedly dependent a variety of maternal traits, including age and reproductive experience (i.e., parity). We evaluated changes in serum concentrations of biomarkers of metabolic activity (total deoxypyridinoline [tDPD] and osteocalcin [OC]) of maternal bone and its relationship to reproductive output and parity throughout pregnancy and lactation in Yorkshire sows. Litter size did not affect bone metabolism; however, serum concentrations of both tDPD and OC were significantly higher in sows with little or no reproductive experience when compared to sows that had produced at least 3 litters prior to the current reproductive bout. This suggests a shift in ability or physiological strategy to meet offspring mineral demands that is acquired or associated with reproductive experience.

Effect of storage time on the characteristics of corn and efficiency of its utilization in broiler chickens

Corn is one of the staple food and feed ingredients in China, therefore its storage is of particular importance. Corn is typically stored for 2 or more years in national barns before it is sold as a food or feed ingredient. However, the effects of stored corn in national barns on the animal performance and nutrient utilization have not been investigated thus far. This study attempted to determine the effects of storage time on the chemical and physical characteristics of corn and its nutritional value, broiler growth performance, and meat quality. Corn grains used in the present study were stored for 4 different periods, from 2 to 5 yr, under the same conditions in a building at the Beijing National Grain Storage Facility. A total of 240 birds in Exp. 1 and 90 birds in Exp. 2 were used to compare the effects of storage time on the utilization of nutrients of corn, the performance, and meat quality of broilers. The content of starch, crude protein, amino acids, fatty acids, and test weight generally decreased with increasing storage time. Corn stored for over 4 yr showed decreased catalase (CAT) and peroxidase (POD) activities and increased fat acidity. Body weight gain (BWG) and European production index (EPI) of broilers from 0 to 3 wk tended to decrease linearly with storage time (0.05 < P < 0.10), and the BWG and EPI of broilers from 4 to 6 wk decreased quadratically (P < 0.05), whereas feed conversion ratio (FCR) increased with storage time (P < 0.05). The FCR, performance, and EPI of broilers positively correlated with CAT activity (P < 0.05), and negatively correlated with fat acidity (P < 0.05). Drip loss of breast muscle increased linearly with corn storage time (P < 0.001); however, pH decreased linearly with corn storage time. Drip loss had a strong negative correlation with POD (P < 0.05). There were no significant differences of the storage length on metabolizable energy (ME), digestibility of crude protein, and starch (P > 0.05). The digestibility of histidine and arginine, and C18:2 and C18:3 changed quadratically with storage time (P < 0.05). Collectively, the results suggest that the use of corn stored for 4 yr in animal feed decreased the performance and meat quality of broilers. Fat acidity, CAT, and POD activities can be used as indexes for evaluating the storage quality of corn.

In vitro bile acid-binding capacity of dietary fibre sources and their effects with bile acid on broiler chicken performance and lipid digestibility

A 4 × 2 factorial experiment was conducted to study the effect of feeding diets-containing dietary fibre (DF) sources and a source of bile acid (BA) on growth performance and lipid metabolism. In addition, in vitro BA-binding capacity of fibre sources was investigated. A total of 256 one-d-old male broiler chickens (Ross 308) were assigned to DF sources [maize-soybean meal (control, C), or 30 g/kg of wheat bran (WB), barley bran (BB) or soybean hulls (SH)] and BA (with or without 1.5 g Na-deoxycholate/kg). Each treatment was replicated 4 times with 8 broiler chickens per cage. The highest in vitro BA-binding capacity was observed with BB (8.76 mg/g BB). From 0 to 21 d, with the addition of BA, the average daily feed intake (ADFI) decreased in broiler chickens fed on the C, WB or BB diets, while there was no difference with the SH diet. With added BA, the average daily gain decreased in broiler chickens fed on the C or SH diets, but it did not change in those fed on the other diets. The addition of BA decreased feed conversion ratio (FCR) in broiler chickens fed on the BB or WB diets, but it increased in those fed on the C or SH diets. Interaction results indicated that the apparent ileal digestibility of lipid increased in broiler chickens fed the C and other DF diets with BA compared to those fed the diets without BA. The addition of BA decreased the pancreas lipase activity (PLA) in broiler chickens fed on the C diet compared to those fed the C diet without BA, while no changes observed in those fed the DF diets with or without BA. No interaction was observed in total liver bile acid (TLBA). The WB, BB and SH with little Na-deoxycholate-binding capacity (<10 mg/g of DF) under in vitro conditions had particular effects with BA on the measured criteria in broiler chickens. The magnitude of improvement in digestibility of lipid with the addition of BA depends on the source of fibre used and the addition of BA in DF diets had little effect on growth performance in young broiler chicken diets.

Amino acid and phosphorus digestibility and concentration of digestible and metabolizable energy in hydrolyzed feather meal fed to growing pigs

Two experiments were conducted to determine the standardized ileal digestibility (SID) of AA (Exp. 1), the standardized total tract digestibility (STTD) of P, and the concentration of DE and ME (Exp. 2) in hydrolyzed feather meal (FM) fed to growing pigs. Eight samples of FM were obtained from 4 different processing plants (FM1, FM2, FM3, and FM4). Each plant provided samples of FM without and with added blood. In Exp. 1, 10 barrows (initial BW: 24.0 ± 0.8 kg) were prepared with a T-cannula in the distal ileum and allotted to a 10 × 10 Latin square design with 10 diets and ten 7-d periods. A N-free diet, a diet based on soybean meal (SBM), and 8 diets based on a combination of SBM and each of the 8 sources of FM were formulated. Values for the SID of CP and AA in each source of FM were calculated using the difference procedure. The SID of CP and all AA was different (P < 0.001) among sources of FM. Among the indispensable AA, the overall effect of addition of blood was statistically significant (P < 0.05) for the SID of Ile, Leu, Lys, Phe, and Val, but for some sources, the SID of these AA was increased by addition of blood, whereas for other sources, the SID was reduced or not changed (interaction, P < 0.05). As an example, the SID of Lys in FM3 and FM4 with added blood were greater (P < 0.05) than in FM3 and FM4 without blood, but no difference in the SID of Lys was observed for FM1 and FM2 without and with blood (interaction, P < 0.01). In Exp. 2, 72 growing barrows (initial BW: 13.3 ± 1.5 kg) were used with 9 diets and 8 replicate pigs per diet. A corn-diet consisting of 98.4% corn was formulated and 8 additional diets were formulated by mixing corn with 25% FM. The STTD of P and the DE and ME of each source of FM were calculated using the difference procedure. The STTD of P tended (P = 0.09) to be different among FM sources and the STTD of P in FM with added blood was less than in FM without blood. On a DM basis, DE and ME values were affected (P < 0.05) by both source of FM and addition of blood. However, an interaction (P < 0.05) between source of FM and addition of blood for ME was observed because addition of blood to FM3 and FM4 reduced (P < 0.05) the ME, whereas addition of blood to FM1 and FM2 had no impact on ME. In summary, the SID of AA, STTD of P, and the energy concentration vary among sources of FM and the effects of adding blood to FM is not consistent among sources.

Effect of the degree and duration of early dietary amino acid restrictions on subsequent and overall pig performance and physical and sensory characteristics of pork

The objective of this study was to investigate the effect of the degree and duration of early dietary AA restrictions on subsequent and overall pig performance and physical and sensory characteristics of pork. For the grower (G) and finisher-1 (F1) phases, 3 corn-soybean meal diets were formulated to contain 100, 80, or 60% of the 1998 NRC total Lys recommendations (100G, 80G, or 60G, and 100F1, 80F1, or 60F1, for the G and F1 phases, respectively). For the finisher-2 (F2) phase, a common corn-soybean meal diet was formulated to satisfy the 1998 NRC total Lys recommendation. Thirty gilts and 30 castrated males (2 gilts or 2 castrated males/pen) were randomly assigned to 5 dietary treatments (100G-100F1, 80G-100F1, 80G-80F1, 60G-100F1, and 60G-60F1) when BW was 22.7 +/- 0.3 kg. Pigs were switched to F1 and F2 diets at 50.7 +/- 0.4 and 79.9 +/- 0.5 kg of BW, respectively. Pigs had ad libitum access to feed and water. All pigs were slaughtered at 110.7 +/- 0.5 kg of BW, and LM samples were collected. Pigs fed the 60G diet had less (P < or = 0.05) ADG during the G phase and greater (P < or = 0.05) ultrasound backfat (UBF) at the end of the G phase than those fed the 100G diet. The ADG decreased linearly (R(2) = 0.70; P < 0.001) as the degree of AA restrictions became more severe. Although serum total protein (TP) and albumin concentrations in pigs fed the 60G-100F1 diets were less (P < or = 0.05) than those fed the 100G-100F1 diets at the end of the G phase, TP concentration was similar between the 2 groups at the end of the F1 phase. Likewise, ADG during the F1 phase and UBF at the end of the F1 phase in pigs fed the 60G-100F1 diets were similar to those fed the 100G-100F1 diets. Feeding the 80G diet resulted in numerically decreased ADG during the G phase, but there was no difference in ADG during the F1 and F2 phases or UBF at the end of F1 and F2 phases between pigs fed the 80G and 100G diets. Overall, pigs fed the 80G-80F1 diets had similar ADG, but less (P < or = 0.05) fat-free lean gain (LG) than those fed the 100G-100F1 diets. These pigs also had less (P < or = 0.05) serum TP and albumin concentrations than pigs fed the 100G-100F1 diets throughout the study. Pigs fed the 60G-60F1 diets had less (P < or = 0.05) overall ADG and G:F and less (P < or = 0.05) LM area and LG than those fed the 100G-100F1 diets. However, they had a greater (P < or = 0.05) subjective marbling score than those fed the 100G-100F1 diets. The results indicated that pigs fed the 80G-80F1 diets may have exhibited compensatory growth in BW gain, but not in terms of lean accretion. Growth performance and carcass traits of pigs fed the 60G-60F1 diets were reduced, indicating that the restriction may have been too severe or too long or both. Early dietary AA restrictions had no clear effect on physical and sensory characteristics of pork.

A regional evaluation of injections of high levels of vitamin A on reproductive performance of sows

A regional study involving 443 litters from 182 sows was conducted at 5 cooperating experiment stations to determine the effects of an i.m. injection of vitamin A at weaning and breeding on subsequent litter size of sows. Sows were assigned to 1 of 3 treatments given at weaning and again at breeding: 1) a placebo i.m. injection (2 mL of corn oil), 2) i.m. injection with 250,000 IU of vitamin A (1 mL of vitamin A palmitate in oil), and 3) i.m. injection with 500,000 IU of vitamin A (2 mL of vitamin A palmitate in oil). Corn-soybean meal diets in gestation were formulated to contain 13% CP and 0.60% total Lys. Lactation diets were formulated to contain 17% CP and 0.90% Lys. A common vitamin-mineral premix that supplied 11,000 IU of vitamin A/kg of diet (as-fed) was used by all stations. As expected, station effects were noted for many response measures. Analysis of the data also revealed both treatment x station and treatment x parity interactions for litter size responses. The treatment x parity interactions were stronger than the treatment x station effects, and when the litter size response was separated into early parity sows (parity 1 and 2) and late-parity sows (parity 3 to 6), the treatment x station interactions were no longer present in either subgroup. For sows of parity 1 and 2, litter sizes were increased linearly (P Collapse

Key Words Collapse

MESH Headings

• Age Factors
• Animal Feed
• Animals
• Body Weight
• Breeding/methods
• Dietary Proteins/administration & dosage
• Dose-Response Relationship, Drug
• Female
• Injections, Intramuscular/veterinary
• Lactation/metabolism
• Lactation/physiology
• Litter Size
• Lysine/administration & dosage
• Parity
• Pregnancy
• Random Allocation
• Reproduction/drug effects
• Glycine max
• Swine/growth & development
• Swine/physiology
• Vitamin A/pharmacology
• Vitamins/pharmacology
• Weaning
• Zea mays

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Grants Collapse

Affiliation(s)

M D Lindemann S-145 Regional Research Committee on Nutrition and Management of Swine for Increased Reproduction Efficiency, Department of Animal and Food Sciences, University of Kentucky, Lexington, Kentucky 40546, USA.
J H Brendemuhl
L I Chiba
C S Darroch
C R Dove
M J Estienne
A F Harper

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Measuring synthesis rates of nitrogen-containing polymers by using stable isotope tracers1,2

The major N-containing polymer compounds in the body include protein, RNA, and DNA. The endogenous gastrointestinal secretions as well as the portal-drained visceral and peripheral immune responses are basic physiological functions. Elevated endogenous secretions and immune activities, as affected by developmental stages, diets, and management factors, decrease the availability of dietary nutrients for peripheral muscle synthesis and deposition. Measurements of in vivo protein, RNA, and DNA synthesis rates associated with the viscera, peripheral immune cells, and skeletal muscles should, in principle, be the sensitive biochemical and cellular endpoints for studying factors affecting nonruminant nutrition, metabolism, and growth. The selection of stable isotope tracers for precursors, routes of tracer delivery, and mass spectrometric analyses of tracer enrichments are the major methodological considerations. To measure in vivo protein, RNA, and DNA synthesis rates, oral feeding with heavy water (2H2O), and continuous infusion of [U-13C]glucose and [15N]Gly intravenously for labeling the sugar moieties ribose and deoxyribose and de novo purine base synthesis have been established. Flooding doses of tracer Phe, for example, L-[ring-2H5]Phe, via the i.p. route are reliable and cost-effective for measuring in vivo protein synthesis rates, especially for the viscera in small nonruminants. Therefore, measurements of the major N-containing polymer synthesis rates in the viscera, the peripheral immune cells, and muscles through oral feeding with 2H2O and/or i.p. flooding doses of Phe tracers are the emerging tools for studying nonruminant nutrition, metabolism, and growth under research and field test conditions.

Compensatory growth and nitrogen balance in grower-finisher pigs

Sixteen castrated male pigs (averaging 21.2 +/- 4.9 kg) were used in two trials to investigate the effect of dietary amino acid content during the grower phase on growth performance and N balance. In each trial, pigs were assigned randomly to corn-soybean meal grower diets formulated to contain 5.0 or 11.0 g lysine/kg (as-fed basis). Common Finisher 1 and 2 diets were offered when pigs reached 51.2 +/- 3.3 and 79.5 +/- 3.4 kg, respectively. Pigs were placed in metabolism crates for a 9-d period during each of the grower, Finisher 1, and Finisher 2 phases when they weighed 43.3 +/- 3.9, 70.4 +/- 4.9, and 90.5 +/- 3.8 kg, respectively, to determine N balance. Blood samples were taken from each pig periodically after an overnight fast. Pigs were allowed ad libitum access to feed and water, except during the three adaptation/collection periods. There were no diet x trial interactions; thus, the data were combined. Pigs fed the low-amino acid grower diet grew more slowly and less efficiently (P < 0.001) during the grower phase and had more ultrasound backfat (P = 0.010) at the end of the grower phase than those fed the high-amino acid grower diet. During the Finisher 1 phase, however, pigs fed the low-amino acid diet grew more efficiently (P = 0.012) than those fed the high-amino acid diet, and the grower diet had no effect on overall weight gain, carcass traits, lean accretion, or meat quality scores. Although pigs fed the low-amino acid diet had less serum urea N (P < 0.001) and more glucose (P = 0.009) at 43.3 kg, there seemed to be no clear, long-term effect of the grower diet on serum metabolites. During the grower phase, pigs fed the high-amino acid diet consumed more N (P < 0.001), had higher apparent N digestibility (P = 0.041), N utilization (P = 0.027), and N retention (P < 0.001), and excreted more fecal (P = 0.034) and urinary (P < 0.001) N than those fed the low-amino acid diet. Pigs fed the low-amino acid grower diet, however, had a higher N utilization (P = 0.024) during the Finisher 1 phase, and excreted less urinary N during both the Finisher 1 (P = 0.029) and 2 (P = 0.027) phases than those fed the high-amino acid grower diet. These results indicate that pigs subjected to early dietary amino acid restrictions compensated completely and decreased N excretion during both the restriction and realimentation phases. Compensatory growth can, therefore, have a positive effect not only on the overall efficiency of pig production but also on environment.

A regional evaluation of chromium tripicolinate supplementation of diets fed to reproducing sows1,2

A cooperative research study involving 353 litters was conducted at three stations to determine the effects of graded levels of supplemental Cr from chromium tripicolinate (CrPic) on reproductive performance of sows and preweaning performance of their pigs. Primiparous and multiparous sows were fed fortified corn-soybean meal diets with supplemental levels of 0, 200, 600, or 1,000 ppb Cr (as-fed basis). Each station used at least three of the supplemental Cr levels, with two of those levels being 0 and 200 ppb. Station effects were observed for sow gestation weight gain, lactation weight change, lactation feed intake, litter size at birth and weaning, and pig weight at birth and weaning (P = 0.001 to 0.087). Supplemental Cr increased the number of pigs born live per litter (9.49, 9.82, 10.94, and 10.07; quadratic, P = 0.05) and sow lactation weight change (-0.2, 0.8, -4.1, and -3.9 kg; linear, P = 0.01) but decreased individual birth weight of total pigs born (1.61, 1.57, 1.47, and 1.56 kg; quadratic, P = 0.10). Tissues were obtained from a subset of sows from one station after they had completed three parities on the study. The content of Cr in the adrenal gland (16.4, 20.0, 34.0, and 48.4 ppb), kidney (35.8, 56.4, 132.6, and 176.0 ppb), and liver (22.8, 37.4, 87.6, and 92.2 ppb) was increased linearly (P = 0.001 to 0.005) by increasing CrPic supplementation. The results suggest that the supplementation level that maximizes the biological response is above that currently allowed. Additionally, supplementation of Cr at 1,000 ppb (five times currently permitted supplementation levels) was not detrimental to sow performance, even when fed continuously for three parities. There may be merit to continued research to evaluate higher supplementation rates.

Growth performance, dry matter and nitrogen digestibilities, serum profile, and carcass and meat quality of pigs with distinct genotypes

We investigated the effect of distinct genotypes on growth performance, DM and N digestibilities, serum metabolite and hormonal profiles, and carcass and meat quality of pigs. Eight control-line and eight select-line pigs with an equal number of gilts and castrated males per genotype were chosen from the group of pigs subjected to selection for lean growth efficiency. Pigs were housed individually and allowed ad libitum access to common grower, finisher 1, and finisher 2 diets when they reached approximately 20, 50, and 80 kg, respectively, and water throughout the study. Although genotype had no effect on growth performance during the finisher 2 phase and overall, select-line pigs grew faster and more efficiently (P < 0.05) during the grower and finisher 1 phases than did control-line pigs. Dry matter and N digestibilities during the grower phase were lower (P < 0.05) in select-line pigs compared with control-line pigs. Select-line pigs had less ultrasound backfat (P < 0.05) at the end of the grower and finisher 2 phases. Serum urea N (P < 0.05) and leptin concentrations were lower in select-line pigs than in control-line pigs, but the effect of genotype on serum glucose, triglyceride, or insulin concentration was rather inconsistent. Select-line pigs had heavier heart (P < 0.05), liver (P = 0.08), and kidneys (P < 0.01), implying a higher metabolic activity. Less 10th-rib carcass backfat (P < 0.01) and a trend for larger carcass longissimus muscle area (P = 0.10) were reflected in the greater (P < 0.01) rate and efficiency of lean accretion in select-line pigs. Select-line pigs had lower subjective meat color (P < 0.01), marbling (P < 0.05), and firmness (P < 0.01) scores. Final serum leptin concentration was correlated positively with carcass backfat thickness (r = 0.73; P < 0.01) and negatively with overall feed intake (r = -0.77; P < 0.01). These results indicate that pigs with distinct genotypes exhibited differences in the growth rate, metabolite and hormonal profiles, and body composition. Further research is necessary to determine whether pigs with distinct genotypes respond differently to dietary manipulations, which would have an effect on developing optimal feeding strategies for efficient and sustainable pig production.

Variability in mixing efficiency and laboratory analyses of a common diet mixed at 25 experiment stations

An experiment involving 25 experiment stations in the North Central and Southern regions (NCR-42 and S-288, respectively) was conducted to assess the degree of uniformity of diet mixing among stations and to assess the variability among station laboratories in chemical analysis of mixed diets. A fortified corn-soybean meal diet was mixed at each station using a common diet formula (except for vitamin and trace-mineral additions). The diet was calculated to contain 14% crude protein (CP), 0.65% Ca, 0.50% P, and 125 ppm Zn (based on 100 ppm added Zn). After mixing, samples were collected from the initial 5% of feed discharged from the mixer, after 25, 50, and 75% was discharged, and from the final 5% of discharged feed. The five samples were sent to the University of Kentucky, finely ground, and divided into subsamples. Each set of five subsamples from each station was distributed to three randomly selected stations for analysis of CP, Ca, P, and Zn (i.e., each station analyzed five diet sub-samples from three other stations). In addition, two commercial and two station laboratories analyzed composites of the five subsamples from each of the 25 mixed diets. Based on the laboratories that analyzed all diets, means were 13.5, 0.65, and 0.52%, and 115 ppm for CP, Ca, P, and Zn, respectively. Ranges of 11.8 to 14.6% CP, 0.52 to 0.85% Ca, 0.47 to 0.58% P, and 71 to 182 ppm of Zn were found among the 25 diet mixes. The coefficients of variation among the 25 diet samples for CP, Ca, P, and Zn were 4.3, 9.3, 4.1, and 17.4%, and among the 25 laboratories were 3.6, 12.5, 10.7, and 11.1%, respectively. Overall analyses of the five sub samples were, respectively, CP: 13.4, 13.6, 13.4, 13.5, and 13.4% (P < 0.06); Ca: 0.66, 0.67, 0.67, 0.66, and 0.67%; P: 0.50,0.51,0.51,0.50, and 0.50%; and Zn: 115, 116, 112, 113, and 120 ppm (P < 0.001). Diets were not uniformly mixed at all stations (station x sample No. was P < 0.08 for Ca and P < 0.01 for CP, P, and Zn). Among stations, the range of the five samples, expressed as a percentage of the mean and averaged for CP, Ca, P, and Zn, varied from +/- 1.1% (i.e., 98.9 to 101.0%) to +/- 12.9% (84.6 to 110.4%), with an overall average of +/- 5.2%. Neither type nor volume of mixers was related to mixing uniformity. The results suggest that uniformity of diet mixes varies among experiment stations, that some stations miss their targeted levels of nutrients (especially Zn), and that the variability among experiment station laboratories in analysis of dietary Ca, P, and Zn in mixed diets is quite large.

Degree of amino acid restrictions during the grower phase and compensatory growth in pigs selected for lean growth efficiency

A total of 32 select line (SL) and 32 control line (CL) Duroc pigs were used in two trials to determine the effect of dietary amino acid contents during the grower (G) phase and selection for lean growth efficiency on growth performance, carcass traits, and meat quality. In each trial, pigs weighing 20 kg were assigned to 16 pens with two gilts or two castrated males per pen, and pens were randomly assigned within the genetic line to corn-soybean meal G diets formulated to contain 5.0, 7.0, 9.0, or 11.0 g lysine/kg. After 50 kg, all pigs were fed common finisher 1 (F1) and finisher 2 (F2) diets. Pigs were allowed ad libitum access to feed and water. After the initial statistical analyses, the data sets from the two trials were combined. During the G phase, pigs consumed less feed [linear (Ln), P < 0.001] and more lysine (Ln, P < 0.001), grew faster (Ln, P < 0.05) but utilized feed more and lysine less efficiently (Ln, P < 0.001) for weight gain as the amino acid content of G diets increased. Increasing dietary amino acids resulted in less ultrasound backfat (Ln, P < 0.001) and more serum urea nitrogen [Ln, P < 0.001; quadratic (Qd), P < 0.01] at the end of the G phase. Pigs grew more slowly during the F1 (Ln, P < 0.01 and Qd, P = 0.05) and F2 (Ln, P = 0.07) phases and utilized feed and lysine less efficiently (Ln, P < 0.05) for weight gain during the F1 phase as the amino acid content of G diets increased. The grower diet had no effect on overall weight gain and feed efficiency, carcass traits, or meat quality scores. The efficiency of lysine utilization for overall weight gain (Ln, P < 0.001) and lean accretion (Ln, P < 0.05) improved as the amino acid content of G diets decreased. The SL pigs grew faster (P < 0.05) and had less (P < 0.001) ultrasound backfat throughout the study compared with the CL pigs. The SL pigs had less 10th rib backfat (P < 0.001) and tended to have larger longissimus muscle area (P = 0.09) than the CL pigs, which were reflected in greater rate (P < 0.001) and efficiency (P < 0.05) of lean accretion. Marbling (P < 0.05) and meat color (P = 0.07) scores were lower in the SL pigs. No grower diet x genotype interactions were observed in response criteria of interest. The results indicate that pigs subjected to dietary amino acid restrictions during the G phase (as low as 5.0 g lysine/kg) compensated completely in terms of growth rate and body composition regardless of the genotype. Compensatory growth can have a positive impact not only on the overall efficiency of pig production but also on the environment by reducing excretion of unused nutrients.

Growth performance and carcass traits of pigs subjected to marginal dietary restrictions during the grower phase

Sixty-four individually housed pigs were used to investigate the effect of amino acid content of finisher diets on growth performance of pigs subjected to marginal dietary amino acid restrictions (80% of the 1988 NRC lysine recommendation) during the grower phase. In each of the two trials, low- and high-amino-acid grower diets (.421 and .765 g lysine/MJ DE, respectively) and four finisher diets (.421, .516, .612, and .707 g lysine/MJ DE) were randomly assigned within sex to 16 gilts and 16 castrated males weighing 23.0 +/- 2.0 kg in a 2 x 4 factorial arrangement of treatments. The average weight of pigs after a completion of diet change was 50.4 +/- 2.1 kg. All pigs were slaughtered at an average weight of 105.2 +/- 4.1 kg. Ultrasound backfat thickness was measured at the time of diet change and before slaughter. Pigs were allowed ad libitum access to feed and water. During the grower phase, pigs fed the high-amino-acid diet grew faster (P < .001) and more efficiently (P < .001) and had less ultrasound backfat (P < .001) than those fed the low-amino-acid diet. The grower diet had no effect on weight gain during the finisher phase. Consequently, pigs fed the high-amino-acid grower diet had better overall weight gain (P < .01) than those fed the low-amino-acid diet. The rate of lean accretion was, however, similar between the two groups of pigs. Furthermore, pigs fed the low-amino-acid grower diet seemed to have better carcass quality, as indicated by less ultrasound backfat (P < .01) and larger carcass longissimus muscle area (P < .05). Average and 10th rib carcass backfat decreased linearly (P < or = .05) and lean accretion rate improved linearly (P < .05) as the amino acid content of finisher diets increased, but there was no grower x finisher diet interaction in these and other response criteria. Although no evidence of compensatory weight gain was observed, it is possible that compensatory lean tissue growth may have occurred in pigs subjected to early amino acid restrictions at the expense of fatty tissue growth.

Supplemental lysine for sows nursing large litters

A cooperative experiment involving 501 litters was conducted at four stations to assess the effects of supplemental lysine on lactational performance of sows nursing large litters. Basal diets were formulated to contain .60% lysine from corn or sorghum and soybean meal. Lysine.HCl (78.8% lysine) was substituted for grain to achieve dietary lysine levels of .75 and .90%. First-parity sows nursed a minimum of nine pigs per litter and older sows a minimum of 10 pigs per litter by d 3 of lactation. Overall mean litter size at 21 d of age was 9.7 pigs. Sows remained on treatment for three successive parities unless culled for structural unsoundness or reproductive failure. Dietary lysine did not affect body weight or backfat loss during lactation, sow ADFI, interval from weaning to estrus, or litter size at birth or at 21 d of age. Mean pig weights at birth and at 21 d of age increased quadratically to increasing lysine, with improvements found at all stations from increasing lysine from .60 to .75%. Twenty-one-day pig weights did not increase at the highest lysine level at stations feeding corn, but did improve at the station feeding sorghum, which resulted in a treatment x station interaction (P < .05). The different responses to lysine on different grain sources indicates intake of one or more other amino acid may have limited lactation performance at the highest level of lysine. These data indicate that a 13% CP corn-soybean meal containing .60% lysine is inadequate for sows nursing large litters and that supplemental synthetic lysine beyond .15% additional lysine will not be beneficial due to a deficiency of one or more other amino acids.

An assessment of dietary folic acid levels during gestation and lactation on reproductive and lactational performance of sows: a cooperative study. S-145 Committee on Nutritional Systems for Swine to Increase Reproductive Efficiency

Crossbred female swine (n = 393) were used in a multiparity study at five experiment stations to evaluate the effects of dietary supplementation of folic acid (FA) on serum folates status and reproductive performance. The dietary treatments were a corn-soybean meal basal diet (calculated FA, .34 ppm) supplemented with 0, 1, 2, or 4 ppm FA. Experimental diets were fed continuously from a minimum of 21 d before first mating throughout the entire study. At one station, blood samples for radioimmunoassay determination of serum folates concentration were collected by vena cava puncture at mating, d 55 of gestation, d 110 of gestation, and at weaning. Stage of reproduction and dietary FA supplementation affected (P < .005) serum folates concentrations. Serum folates declined from mating to d 55, remained low at d 110, and returned to higher levels at weaning. Linear increases (P < .001) in serum folates with increasing level of dietary FA were observed at each reproductive stage. Over the course of the study, reproductive performance criteria including total pigs born, live pigs at birth and d 21, and individual pig and litter weight at birth and d 21 were not affected (P > .10) by inclusion of FA in the diet. The number of days postweaning to estrus also was not affected by FA treatment. Under the conditions of this experiment, increasing level of FA in the diet had a pronounced effect in attenuating decreased serum folates concentration during gestation but was without benefit to reproductive performance.

Amino acid and energy interrelationships in pigs weighing 20 to 50 kilograms: II. Rate and efficiency of protein and fat deposition

Two experiments were conducted to investigate the relationships between amino acids and DE for pigs weighing 20 to 50 kg. In Exp. 1, there were three dietary lysine levels that were either adjusted (1.50, 2.35 and 3.20 g/Mcal DE) for five DE levels (3.00 to 4.00 Mcal/kg) or unadjusted (.45, .71 and .96% of the diet) for three DE levels (3.50 to 4.00 Mcal/kg). In Exp. 2, diets containing six lysine:DE ratios (1.90 to 3.90 g/Mcal) at two DE levels (3.25 and 3.75 Mcal/kg) were fed. Pigs were housed individually, and could eat and drink ad libitum. When pigs weighed 50 kg, their empty body composition was determined by the urea dilution technique in Exp. 1 and by prediction equations based on backfat in Exp. 2. For the adjusted diets in Exp. 1, protein deposition and protein deposition:DE intake increased (P less than .01) slightly as DE levels increased. These criteria decreased linearly (P less than .001), and fat deposition increased (P = .11) as DE increased when lysine:DE ratios were not maintained. As lysine levels increased, protein deposition and protein deposition: DE intake increased (P less than .001) in both the adjusted and unadjusted diets. In Exp. 2, there was no effect of DE on either the rate or efficiency of protein deposition. Both protein deposition and protein deposition:DE intake increased (P less than .001) and fat deposition decreased as lysine:DE ratios increased up to 3.00 g lysine/Mcal DE. Protein deposition: lysine intake decreased (P less than .01) progressively as the lysine:DE ratio increased. Regression analyses indicated the protein deposition increased up to 3.00 g lysine/Mcal DE. The results demonstrate the need to adjust lysine according to energy levels and indicate that the optimum ratio for protein deposition was approximately 3.00 g lysine/Mcal DE (or 49 g of balanced protein/Mcal DE).

Amino acid and energy interrelationships in pigs weighing 20 to 50 kilograms: I. Rate and efficiency of weight gain

The relationships between dietary amino acids and DE for pigs weighing 20 to 50 kg were investigated in two experiments. In Exp. 1, there were three dietary lysine levels that were either adjusted (1.50, 2.35 and 3.20 g/Mcal DE) for five DE levels (3.00 to 4.00 Mcal/kg) or unadjusted (.45, .71 and .96% of the diet) for three DE levels (3.50 to 4.00 Mcal/kg). In Exp. 2, the effects of six lysine:DE ratios (1.90 to 3.90 g/Mcal) at two DE levels (3.25 and 3.75 Mcal/kg) were investigated. In both experiments, diets were formulated using a constant ratio of corn and soybean meal. Pigs (equal numbers of barrows and gilts) were housed and fed individually and had ad libitum access to feed and water. Digestible energy intake was not affected by energy content of the diets. In Exp. 1, lysine intake did not differ with DE in the adjusted diets but decreased (P less than .001) as DE increased in the unadjusted diets. Weight gain was relatively consistent and gain:DE intake increased (P less than .001) as DE increased in the adjusted diets, but both decreased (P less than .005) with increasing DE in the unadjusted diets. Both criteria increased (P less than .001) in response to higher lysine:DE in the adjusted and lysine in the unadjusted diets. In Exp. 2, weight gain increased (P less than .005), but there was no effect (P greater than .05) on gain:DE intake as DE increased. Both weight gain and gain:DE intake increased (P less than .001) and backfat decreased (P less than .01) as lysine:DE ratios increased. The results demonstrate the need to increase dietary amino acid levels in concert with increases in energy contents. Regression analyses indicated that weight gain and gain:DE intake for 20- to 50-kg pigs were maximized at approximately 3.0 g lysine/Mcal DE (or 49 g of balanced protein/Mcal DE).

Efficacy of the urea dilution technique in estimating empty body composition of pigs weighing 50 kilograms

The efficacy of the urea dilution technique in estimating the empty body composition of pigs weighing 50 kg was evaluated in three trials using 17 contemporary (Large White X Landrace X Hampshire X Duroc) and 8 Nebraska Gene Pool X contemporary pigs. Blood samples were collected via ear catheter before infusion (-60, -30 and 0 min) and at various times (3 to 90 min) after urea infusion (2.16 mmol/kg live BW), and analyzed for plasma urea. Backfat thickness of live pigs from the contemporary line was measured ultrasonically. Pigs then were killed by euthanasic injection, and total bodies (with gastrointestinal contents removed) were analyzed for water, protein and fat. In Trials 1 and 2, there were linear relationships (P less than .001) between chemically determined body water and fat and between body water and protein. Urea space was related (P less than .05) to empty body components with few exceptions, but regression coefficients for urea space in Trial 3 were different from those of Trials 1 and 2. Inclusion of additional independent variables with urea space improved estimation of empty body components. Although backfat alone did not estimate empty body components (except fat) as well as urea space alone, the addition of other common independent variables resulted in better estimates using backfat than urea space. The results of this experiment indicate that the urea dilution technique can be used to estimate the body composition of growing pigs. However, the accuracy obtained depended on the population of pigs being investigated and was no greater than the accuracy with appropriate equations based on backfat.

Effect of dietary fat on pig performance and dust levels in modified-open-front and environmentally regulated confinement buildings

Four trials were conducted with 1,480 pigs (initial wt: 23 kg in trial 1,29 kg in trial 2 and 49 kg in trial 3 and 4) to determine the effect of dietary fat on pig performance, nutrient separation in an automated feed distribution system, dust levels in swine buildings and integrity of the respiratory system of swine. Two modified-open-front (B-1 and B-2) and two environmentally regulated (E-1 and E-2) growing-finishing buildings, of identical design, were used in each trial. In trial 1, 250 pigs (25 pens of 10 pigs/pen) in B-1 were fed a ground, mixed, corn-soybean meal diet (15% crude protein) with added tallow (5%), and 250 pigs in B-2 were fed the same diet but without added tallow. The assignment of diets to buildings were reversed in trial 2 in which 2.5% tallow was used instead of 5%. Each diet was fed ad libitum to pigs, and was distributed by an automated "Flexauger" system in trials 1 and 2. In each of trials 3 and 4, 120 pigs (12 pens of 10 10 pigs/pen) in E-1 were fed a corn-soybean meal diet (14% crude protein) with added tallow (5%) and 120 pigs in E-2 were fed the same diet but without added tallow. Overall, pigs fed the diet with tallow gained faster (P less than .002), consumed less feed (P less than .02) and converted feed more efficiently (P less than .002) than those fed the diet without tallow in trials 1 and 2. Pig performance was also improved by the addition of tallow to the diet in trials 3 and 4 (P less than .002). Crude protein, Ca, P and Cu contents of both diets were similar at each location sampled throughout the automated distribution system in trials 1 and 2. Addition of tallow to the diets reduced aerial dust levels, both with the feed distribution auger running (P less than .002) and without the auger running (P = .06) in trials 1 and 2. In trials 3 and 4, adding 5% tallow to the diet reduced aerial dust concentrations of of particle sizes of 14, 4, and 1.5 micron (P less than .002) and .4 micron (P = .07). The amount of settled dust was lower (P less than .001, trials 1, 3 and 4) when tallow was included in the diet.(ABSTRACT TRUNCATED AT 400 WORDS)