Development and validation of equations to predict the metabolizable energy value of corn for pigs.

Three experiments were conducted with the aim of developing and validating an equation to predict the ME of corn for pigs from its chemical composition, physical characteristics and particle size. Exp. 1: Eight lots of corn were ground in a hammer mill, using 5 sieves with different screen opening sizes, generating 40 batches of ground corn. The chemical composition (DM, CP, ether extract, crude fiber, ADF, NDF, and ash) and physical characteristics (bulk density- BD and 1,000-kernel weight- TKW) were determined in the 8 lots and geometric mean diameter (GMD) and N-corrected ME (AMEn) were determined in the 40 batches of corn. The AMEn values were determined in 16 metabolism assays with pigs. Mathematical models were adjusted by regression analysis, based on the Akaike Information Criterion. Based on statistical parameters ( = 0.76 and prediction error = 1.05%), number of predictor variables, and easiness of measurements, an equation with 2 segments was chosen: y = 2845.41 + 0.9385 × BD - 20.8784 × CP, if GMD ≤ 522.98 and y = 3105.75 - 0.4978 × GMD + 0.9385 × BD - 20.8784 × CP, if GMD > 522.98. Exp. 2 and 3: Sixty four gilts (Exp. 1; 29.5 ± 3.8 kg) and 64 barrows (Exp. 2; 29.3 ± 3.6 kg), 1 lot of corn, and 3 particle sizes (GMD = 483, 632, and 904 µm) were used in a 3 × 2 factorial arrangement with 2 methods of diet formulation, differing in ME value of corn: "FIX" (value from nutrient composition table) vs. "ESTIMATED" (estimated for each particle size using the equation developed in Exp. 1). In Exp. 2, ADFI was greater ( < 0.05) and feed efficiency was lower ( < 0.05) in the diet with GMD of 904 µm compared to the diets with GMD of 632 or 483 µm, but only for diet formulation by the FIX method. In the treatments with GMD of 483 µm, gilts fed with the diet formulated by the ESTIMATED method had greater ( < 0.10) ADFI, backfat, fat area, and fat:meat ratio than gilts fed the diet formulated by the FIX method. In Exp. 3, particle size and formulation method did not affect ( > 0.10) growth performance and carcass traits of barrows. The equation developed was effective to adjust the ME value of corn, considering particle size variation. However, improvement to the proposed equation is necessary to achieve greater precision for predicting corn ME. Validation of the equation with more lots of corn of different chemical compositions and densities appears necessary to assess the efficacy of the equation regarding the variation of the other predicting variables.

Live performance, carcass quality, and economic assessment of over 100kg slaughtered pigs / Desempenho, qualidade de carcaça e avaliação econômica de suínos abatidos acima de 100kg

Recent genetic improvement has developed pigs with maximum potential for protein deposit at higher weights; however, their optimal slaughter weight still needs to be determined. The objective of the study was to evaluate live performance, carcass traits, and economic viability of 417 Agroceres PIC pigs slaughtered with 100, 115, 130, and 145kg live weight. Pigs were reared in pens with 10-11 barrows and gilts each, offered a feed allowance of 2.8kg/pig/day until the following slaughter weights (SW): 99.65±0.82kg, 118.53±0.98kg, 133.97±1.17kg, and 143.90±1.24. There was no interaction between sex and SW (P>0.05). Backfat thickness, fat area, and loin eye area linearly increased with SW (P<0.001; R2: 70.12-77.44%), and carcass yield increased in a quadratic manner (P<0.001; R²=24.66%). Lean yield was not affected (P>0.05), and feed conversion ratio (R²=43.29%) linearly worsened with SW (P<0.001), but the effect of SW on live production cost (R$/kg) was quadratic, with the minimum point at 134.8kg. It was concluded that, under the applied management, increasing SW results in larger amount of lean tissue with no change in its yield and little effect on growth performance.

A evolução das linhagens sintéticas de suínos propiciou a obtenção de animais com potencial máximo de deposição proteica em pesos superiores; entretanto o peso ótimo de abate dessas linhagens não é conhecido. O objetivo do estudo foi avaliar o desempenho, características de carcaça e avaliação econômica de 417 suínos da linhagem Agroceres PIC abatidos com 100, 115, 130 e 145kg de peso vivo. Os suínos foram criados em baias com 10-11 machos ou fêmeas, com fornecimento programado de 2,8kg de ração por animal, por dia, a partir de 80kg até os pesos de abate (PA) de 99.65±0.82kg, 118.53±0.98kg, 133.97±1.17kg, e 143.90±1.24. Não houve interação entre sexo e PA (P>0,05). A espessura de toucinho, área de gordura e área de olho de lombo aumentaram linearmente com o PA (P<0,001; R² entre 70,12 e 77,44%), e o rendimento de carcaça aumentou de forma quadrática (P<0,001; R²=24,66%). A porcentagem de carne magra não foi afetada (P>0.05) e a conversão alimentar (R²=43,29%) apresentou discreta piora linear com o PA (P<0,001), mas o efeito sobre o custo de produção (R$/Kg) foi quadrático, com ponto de mínima aos 134,85kg. Conclui-se que, com o manejo utilizado, a elevação do PA resulta em aumento na quantidade de carne produzida sem alteração no seu rendimento e apresenta pouco efeito sobre o desempenho.

Meat quality and cut yield of pigs slaughtered over 100kg live weight / Qualidade de carne e rendimento de cortes de suínos abatidos acima de 100kg de peso vivo

Meat quality and cut yield of pigs slaughtered between 100 and 150kg live weight were evaluated. Pigs (417 Agroceres PIC barrows and gilts) were fed a daily allowance of 2.8kg per head from 80kg until 100.71±0.85, 118.58±0.99, 134.07±1.18 or 143.90±1.24kg live weight. Seventy-one pigs were used for the evaluation of primal and subprimal cuts. There was no interaction between sex and slaughter weight for any of the evaluated parameters. Ham, shoulder, and loin weights linearly increased (P<0.01; R2: 84.3-93.2%) with increasing slaughter weight, which, however, had little effect on primal cuts meat yield. Increasing slaughter weight promoted a linear (P<0.05) and a quadratic (P<0.01) increase of red/green coordinate (a* value) of the loin and ham, respectively. Shear force showed a quadratic response (P<0.05), with minimum value estimated at 122kg slaughter weight. It was concluded that, under the applied management, increasing slaughter weight increased the volume of meat, but had little effect on meat yield. The meat of pigs slaughtered at heavier weights showed more intense red color and the same intramuscular fat content as lighter pigs, while tenderness was slightly affected.

Foi avaliada a qualidade da carne e os cortes de suínos abatidos entre 100 e 145kg de peso vivo. Os suínos (417 machos castrados e fêmeas, linhagem Agroceres PIC) foram mantidos sob fornecimento programado de 2,8kg de ração por animal por dia a partir de 80kg até o abate aos: 100,71±0,85, 118,58±0,99, 134,07±1,18 ou 143,90±1,24kg de peso vivo. Destes, 71 suínos foram usados para avaliação dos cortes primários e secundários. Não foi observada interação entre sexo e peso de abate em nenhuma das variáveis avaliadas. Os pesos do pernil, da paleta e do carré aumentaram linearmente (P<0,01; R2entre 84,3 e 93,2%) com o peso de abate, com pouco efeito sobre o rendimento da carne. A coordenada vermelho/verde (valor de a*) aumentou linearmente (P<0,05) no lombo e de forma quadrática (P<0,01) no pernil com o aumento do peso de abate. A força de cisalhamento apresentou resposta quadrática (P<0,05), com redução até o valor mínimo estimado para os 122kg de peso vivo. Conclui-se que, com o manejo utilizado neste estudo, a elevação do peso de abate resulta em aumento na quantidade de carne produzida, com pouco efeito sobre o rendimento de carne. A carne de suínos abatidos em pesos elevados apresenta cor vermelha mais intensa e mesmo nível de gordura intramuscular que a carne de suínos mais leves, enquanto a maciez é alterada apenas de maneira discreta.

Effects of genotype and dietary oil supplementation on performance, carcass traits, pork quality and fatty acid composition of backfat and intramuscular fat.

A 42-day study was conducted to evaluate the effect of genotype: terminal sire line Duroc×F1 (DC×F1); terminal sire line Embrapa MS-115×F1 (MS-115×F1); and MS-115×Moura (MS-115×MO) and three dietary oil sources: soybean; canola; and canola+flax, on performance, carcass traits, pork quality, and fatty acid composition. Genotype affected the technological quality of pork and fatty acid profile. MS-115-sired pigs had better meat color and Duroc-sired pigs had higher intramuscular fat content, more saturated fat and better omega-6/omega-3 ratio. Moura breed influenced positively meat tenderness and intramuscular fat. Diet did not affect the technological quality of the meat. Canola or canola+flax oil diet supplementations increased monounsaturated and C18:3 and decreased C18:2 fatty acids, reducing the omega-6/omega-3 ratio. The best omega-6/omega-3 ratio was obtained through supplementation with canola+flax.

Effect of feed withdrawal and dietary energy source on muscle glycolytic potential and blood acid-base responses to handling in slaughter-weight pigs.

The effects of dietary energy source and feed withdrawal on muscle glycolytic potential (GP) and blood acid-base responses to handling were investigated in slaughter-weight pigs (initial BW 94.7 ± 1.01 kg). Crossbred pigs (n = 96; 48 barrows, 48 gilts) were used in a randomized complete block design with a 4 × 2 × 2 factorial arrangement of treatments: l) diet [control, high fat (10% supplemental fat), low-digestible carbohydrate (20% total starch), and high-fat/low-digestible carbohydrate (10% supplemental fat and 20% total starch)]; 2) feed withdrawal (0 and 36 h); and 3) sex (barrow and gilt). Diets were fed for 28 d before the feed withdrawal treatment was applied, at the end of which all pigs were individually moved through a 12.20-m-long × 0.91-m-wide passageway for 16 laps (195 m total distance), with the assistance of an electric goad (2 times per lap). Longissimus muscle biopsies were collected at the beginning of the feeding and feed withdrawal periods and immediately after and 4 h after the handling procedure. Venous blood was collected 2 h before and immediately after the handling procedure to measure acid-base responses. At the end of the feeding period, pigs fed the control and high-fat diets were heavier (P < 0.001) than those on the low-digestible carbohydrate and the high-fat/low-digestible carbohydrate diets (129.8, 130.9, 114.0, and 122.1 kg, respectively; SEM 1.91). Diet, feed withdrawal, and sex did not affect (P > 0.05) blood acid-base responses to handling. Muscle GP at the end of the feeding period and 4 h posthandling was least (P < 0.05) for pigs fed the high-fat diet and similar for the other 3 diet treatments. Pigs subjected to 36 h compared with 0 h of feed withdrawal had less GP (P < 0.05) immediately after and 4 h after the handling procedure. There was an interaction between diet and feed withdrawal treatments for changes in GP from the start of feed withdrawal to 4 h posthandling. The reduction in GP was greater (P < 0.05) for fasted than for fed pigs receiving the control and high-fat diets, but was similar (P > 0.05) for fasted and fed pigs receiving the 2 low-digestible carbohydrate diets. In conclusion, neither dietary energy source nor fasting affected blood acid-base responses to handling; however, fasting-induced changes in LM GP were diet dependent.

Effect of feed withdrawal and handling intensity on longissimus muscle glycolytic potential and blood measurements in slaughter weight pigs.

This study was carried out to evaluate the effect of feed withdrawal and handling intensity on blood acid-base responses and muscle glycolytic potential in slaughter-weight pigs. Sixty crossbred pigs (BW = 107.7 +/- 0.56 kg; 44 barrows and 16 gilts) were used in a randomized complete block design with a 2 x 2 factorial arrangement of treatments: 1) feed withdrawal (0 vs. 24 h), and 2) handling intensity (low vs. high). The high-intensity handling treatment consisted of moving the pigs through a passage (12.2 m long x 0.91 m wide) for eight laps using an electric goad two times per lap. Pigs in the low-intensity handling treatment were moved at their own pace through the passage for eight laps using a livestock panel and paddle. Biopsy samples were collected from the LM at the beginning of feed withdrawal, at the end of the handling procedure, and 4 h after handling. Blood samples were collected 2 h before and immediately after the handling procedure. There were no interactions between feed withdrawal and handling intensity for any of the variables measured. Feed withdrawal decreased (P < 0.05) baseline and posthandling body temperature (38.85 vs. 38.65 degrees C; SEM = 0.060 and 39.70 vs. 39.37 degrees C; SEM = 0.04, respectively) and blood glucose, lowered (P < 0.05) baseline partial pressure of oxygen and partial pressure of carbon dioxide, and increased (P < 0.01) baseline and posthandling plasma free fatty acid concentrations. High-intensity handling produced higher (P < 0.01) posthandling lactate and glucose, and lower (P < 0.01) posthandling blood pH (7.33 vs. 7.18 +/- 0.02, respectively), bicarbonate, base excess, and total carbon dioxide than low-intensity handling. Longissimus muscle glycolytic potential of fasted pigs was lower (P < 0.01) than in fed pigs at the end of the handling procedure (177.2 vs. 137.0 micromol/g of wet tissue; SEM = 10.08, respectively). There was no effect of handling intensity on longissimus muscle glycolytic potential. Feed withdrawal did not attenuate the blood acid-base changes caused by handling; however, the combination of feed withdrawal and handling decreased muscle glycolytic potential.

Effects of dietary supplementation with L-carnitine and fat on blood acid-base responses to handling in slaughter weight pigs.

Blood acid-base responses to handling were evaluated in slaughter weight pigs fed diets supplemented with l-carnitine and fat. The study was carried out as a randomized block design with a 2 x 2 factorial arrangement of treatments: 1) dietary L-carnitine supplementation (0 vs. 150 ppm, as-fed basis); and 2) dietary fat supplementation (0 vs. 5%, as-fed basis). Sixty pigs (91.1 +/- 5.14 kg BW) were housed in mixed-gender groups of five and had ad libitum access to test diets (0.68% true ileal digestible lysine, 3,340 kcal of ME/kg, as-fed basis) for 3 wk. At the end of the feeding period (110.3 +/- 7.52 kg BW), pigs were subjected to a standard handling procedure, which consisted of moving individual animals through a facility (12.2 m long x 0.91 m wide) for eight laps (up and down the facility), using electric prods (two times per lap). There was no interaction between dietary L-carnitine and fat supplementation for any measurement. Pigs fed 150 ppm of supplemental L-carnitine had lower baseline blood glucose (P < 0.05) and higher baseline blood lactate (P < 0.05) concentrations than the nonsupplemented pigs. After handling, pigs fed L-carnitine-supplemented diets had a higher (P < 0.05) blood pH and showed a smaller (P < 0.05) decrease in blood pH and base excess than those fed the nonsupplemental diets. Baseline plasma FFA concentrations were higher (P < 0.01) in pigs fed the 5% fat diet. After the handling procedure, blood glucose, lactate, and plasma FFA were higher (P < 0.05) in pigs fed the 5 vs. 0% fat diets, but blood pH, bicarbonate, and base excess were not affected by dietary fat. The handling procedure decreased (P < 0.01) blood pH, bicarbonate, base excess, and total carbon dioxide and increased (P < 0.01) blood lactate, partial pressure of oxygen, and glucose, and also increased (P < 0.01) rectal temperature. Free fatty acid concentrations were increased by handling in pigs fed both 0 and 5% fat and 150 ppm L-carnitine. In conclusion, dietary L-carnitine supplementation at the level and for the feeding period evaluated in the current study had a relatively small but positive effect on decreasing blood pH changes in finishing pigs submitted to handling stress; however, dietary fat supplementation had little effect on blood acid-base balance.

Effects of handling intensity and live weight on blood acid-base status in finishing pigs.

The objective of this study was to determine the effect of live weight on the plasma acid-base response of pigs subjected to various handling intensities. Eighty pigs (equal numbers of barrows and gilts) were used in a completely randomized block design with a 2 x 2 x 2 factorial arrangement of the following treatments: 1) live weight (light [104 kg] vs. heavy [128 kg]), 2) handling intensity (low vs. high), and 3) gender (barrows vs. gilts). Before the handling test, pigs were weighed, venous blood samples were taken to establish baseline levels, and rectal temperature was measured. Pigs were allowed to rest for 2 h before being subjected to the handling treatments, which consisted of moving the pigs through a course (12.2 m long x 0.91 m wide), for a total of eight laps. Animals on the high-intensity treatment were moved rapidly through the course and subjected to a total of 16 single shocks (two shocks per lap) with an electric livestock goad, whereas pigs on the low-intensity treatment were moved at their own pace using a moving panel and a paddle. Rectal temperature and a venous blood sample were taken immediately after handling and at 2 h after handling. Blood plasma was assayed for pH, partial pressure of carbon dioxide (PCO2), partial pressure of oxygen (PO2), saturated oxygen (SO2), total carbon dioxide (TCO2), bicarbonate (HCO3), base excess, and lactate. Live weight had no effect on the baseline measurements. After handling, light pigs had higher (P < 0.05) blood SO2 (65.6 vs. 57.2+/-2.80%) and showed a greater (P < 0.05) increase in PO2 from baseline to post-handling than heavy pigs (15.6 vs. 8.3+/-2.63 mmHg). Post-handling, pigs on the high- compared with the low-intensity handling treatment had greater (P < 0.001) lactate (19.1 vs. 4.9+/-0.56 mmol/L) and PO2 (51.6 vs. 36.5+/-2.44 mmHg) with lower (P < 0.001) TCO2 (18.6 vs. 34.7+/-0.64 mmol/L), pH (7.02 vs. 7.36+/-0.015), HCO3 (16.7 vs. 33.0+/-0.62 mmol/L), and base excess (-14.2 vs. 7.5+/-0.75) values. There were no effects of gender on blood measurements or rectal temperatures. Results from this study highlight a major effect of pig handling intensity, a limited effect of live weight, and no effect of gender on blood acid-base responses to handling.