Impact of dietary analyzed calcium to phosphorus ratios and standardized total tract digestible phosphorus to net energy ratios on growth performance, bone, and carcass characteristics of pigs.

A total of 2,184 pigs (337 × 1,050, PIC; initially 12.4 ± 0.17 kg) were used in a 143-d study to evaluate the effects of feeding varying analyzed calcium to phosphorus ratios (Ca:P) at two standardized total tract digestible (STTD) phosphorus to net energy ratios (STTD P:NE). Pens of pigs (26 pigs per pen) were assigned to 1 of the 6 dietary treatments in a 2 × 3 factorial with main effects of STTD P:NE and Ca:P ratio. Diets consisted of two levels of STTD P:NE; High (1.80, 1.62, 1.43, 1.25, 1.10, and 0.99 g STTD P/Mcal NE from 11 to 22, 22 to 40, 40 to 58, 58 to 81, 81 to 104, and 104 to 129 kg, respectively); or Low (75% of the High levels), and three analyzed Ca:P ratios (0.90:1, 1.30:1, and 1.75:1). There were 14 pens per treatment. Diets were corn-soybean meal-based and contained a constant phytase concentration within each dietary phase with levels decreasing throughout the trial (phases 1 through 3, 500 FTU/kg, assumed release of 0.13% STTD P; phase 4, 400 FTU/kg, assumed release of 0.11% STTD P; phase 5, 290 FTU/kg, assumed release of 0.09% STTD P; and phase 6, 210 FTU/kg, assumed release of 0.07% STTD P). Overall, there was a Ca:P × STTD P:NE interaction (P < 0.05) observed for average daily gain (ADG), feed efficiency (G:F), final body weight (BW), hot carcass weight (HCW), bone mineral density, bone mineral content, and bone-breaking strength. When feeding Low STTD P:NE levels, increasing the analyzed Ca:P ratio decreased (linear, P < 0.001) ADG final BW, HCW, and tended to worsen G:F, bone mineral density, and bone mineral content (linear, P < 0.10). However, when feeding High STTD P:NE levels, increasing the analyzed Ca:P ratio significantly improved bone mineral content and bone mineral density (linear, P < 0.05), and tended to improve ADG and final BW (linear, P < 0.10) and G:F (quadratic P < 0.10). Additionally, increasing the analyzed Ca:P ratio worsened ADG, G:F, and bone mineralization with Low STTD P:NE but had marginal impacts when adequate STTD P:NE was fed.

Calcium (Ca) and phosphorus (P) are the most abundant minerals in the pig and are involved in lean tissue deposition and synthesis and maintenance of the skeletal structure. Swine diets are typically formulated with low margins of safety for P and excess P in the diet can lead to increased P excretion, which can result in negative environmental effects. To have an adequate utilization of both Ca and P, it is important to consider the Ca:P ratio when formulating pig diets. Research has shown that a wide Ca:P is detrimental to pig growth performance and bone mineralization when diets are low in STTD P. Therefore, the objective of this study was to evaluate the impact of varying Ca:P ratios fed at two levels of STTD P:NE on growth performance, bone, and carcass characteristics of pigs from 12 to 129 kg. When P levels were below requirement estimates, widening the Ca:P ratio from 0.90:1 to 1.75:1 reduced growth performance and bone mineralization; however, widening the Ca:P ratio improved performance and bone mineralization when P levels of the diet were above requirement estimates.

Optimal Standardized Ileal Digestible Total Sulfur Amino Acids to Lysine REQUIREMENTS Are Increased in Nursery Pigs Raised under Antibiotic-Free Feeding Regime.

This study aimed to investigate the effect of increasing the standardized ileal digestible (SID) total sulfur amino acid to lysine (TSAA:Lys) on the growth performance of nursery pigs raised with or without antibiotics (AGP) and to determine the optimal SID TSAA:Lys in nursery pigs raised without AGP. In Exp. 1, 924 nursery pigs (7.9 ± 1.3 kg), blocked by initial BW and sex, were randomly allotted to one of six treatments, with seven pens per treatment and twenty-two pigs per pen. The treatments were arranged in a 2 × 3 factorial design, with two AGP levels (0 or 50 mg/kg Carbodox) and three levels of SID TSAA:Lys (51.0, 58.5 or 66.0%). In Exp. 2, 990 weaned piglets (5.1 ± 0.9 kg), blocked by initial BW and sex, were randomly allotted to one of five dietary treatments (SID TSAA:Lys at 51, 58, 65, 72 or 79%) in the absence of AGP, with nine pens per treatment and twenty-two pigs per pen. Competing heteroskedastic models including broken-line linear (BLL), broken-line quadratic (BLQ), and quadratic polynomial (QP) were fitted for the growth performance data to estimate the optimal TSAA:Lys. In Exp. 1, AGP supplementation increased (p < 0.05) ADG and ADFI during the 21 d period. Increasing SID TSAA:Lys in the diets with AGP did not affect growth performance; however, increasing SID TSAA:Lys in the diets without AGP resulted in a linear increase (p < 0.05) in ADG and G:F. In Exp. 2, the best-fitting models for ADG and G:F from d 0 to 21 post-weaning were BLL, which yielded the optimal SID TSAA:Lys of 62% and 72%, respectively. The best-fitting models for ADG and G:F from d 21 to 42 post-weaning were BLL, which yielded the optimal SID TSAA:Lys of 59% and 58%, respectively. In conclusion, SID TSAA to Lys requirements under an antibiotic-free feeding regime during the first 21 d post-weaning were 62% and 72% in terms of ADG and G:F, respectively, whereas an SID TSAA:Lys of approximately 58% was required to maximize ADG and G:F for the late nursery phase.

Soybean oil supplementation for sows in the first three days after farrowing.

One of the main causes of death in newborn piglets is the low level of energy reserves to maintain their body temperature, which can lead to hypothermia and, subsequently, death. Thus, the objective of this study was to evaluate the effect of soybean oil supplementation to sows in the first three days after farrowing to save piglet fat reserves through the higher nutritional intake of sow milk. In total, 604.5, 750, 1000, 1250 and 1500 g of soybean oil were provided for each sow during the three days of supplementation. A total of 60 sows were evaluated per treatment, distributed in a random block design, supplemented in the first three days after farrowing with soybean oil added on top of the feed at the time of feeding. Performance and reproductive data and milk samples were collected from the sows to determine fat levels. Piglets were evaluated for fall-back rate and survival. There was no significant effect of soybean oil supplementation on any of the parameters evaluated for both sows and their milk. Therefore, soybean oil supplementation for sows in the first three days after farrowing does not influence performance parameters, reproduction and milk fat of the sows and mortality and fall-back rate of the piglets.

Impact of feed intake in early gestation on maternal growth and litter size according to body reserves at weaning of young parity sows.

The effect of increasing the feed level (1.8, 2.5, and 3.2 kg/d) during early gestation in parity 1 (PO1) and parity 2 (PO2) sows on maternal growth and litter size was evaluated. A total of 361 sows were group-housed and fed a diet based on a corn-soybean meal (3.15 Mcal Metabolizable Energy (ME) per kg and 0.68% standardized ileal digestible lysine) from day 6 of gestation until day 30. Sows were weighed at weaning and on day 30 of gestation. Farrowing rate, number of total piglets born, piglets born alive, stillborn piglets, and mummified fetuses were recorded at farrowing. The effect of feed level on the total number of piglets born was also evaluated according to classes of body weight (BW), body condition score (BCS), backfat (BF), and caliper unit at weaning for each parity order. There was no evidence for significant effect of the interaction between feed level × parity on the variables related to maternal growth and reproductive performance (P ≥ 0.128). Greater feed levels linearly increased the gains in body condition (i.e., BW, BCS, BF, and caliper unit) between weaning and day 30 of gestation (P < 0.001). Farrowing rate was not influenced by the feed level (P ≥ 0.200) and parity (P ≥ 0.209). The number of total piglets born decreased linearly as the feed level increased (P = 0.041), whereas no evidences for differences were observed on piglets born alive among treatments (P ≥ 0.317), neither between parities (P ≥ 0.904). For PO1 sows, the total piglets born on BW classes (≤183 vs. >183 kg) and on classes of BF (≤11.5 vs. > 11.5 mm) were quadratically affected by the feed levels (P ≤ 0.041). In contrast, the number of total piglets born was marginally affected (linear; P ≤ 0.094) by the feed level in the different classes of BW, BCS, and caliper unit in PO2 sows. There was no evidence for differences for the interaction of feed level and classes of body condition (P ≥ 0.199) for PO2 sows. Similarly, no interactions between feed level and classes of BW, BCS, and BF at weaning were observed (P ≥ 0.233) for PO1 sows; however, the total piglets born were affected by an interaction between feed level and caliper unit class (P = 0.042). In conclusion, increased feed intake from day 6 of gestation until day 30 resulted in increased maternal BW gain but reduced the number of total piglets born. Furthermore, lighter and in a poor BCS PO1 sows at weaning produced fewer total born piglets with no benefits from greater amounts of feed.

Impact of increasing weaning age on pig performance and belly nosing prevalence in a commercial multisite production system.

The effects of increasing weaning age in a commercial production system on nursery and finishing performance were evaluated. A total of 1,176 pigs (PIC 337 × Camborough) were used in a 136-d growth trial with 14 and 10 replications/weaning age on the nursery and finishing phases, respectively. Treatments included weaning litters at 19, 22, 25, or 28 d of age. In the nursery, as weaning age increased, initial (5.04, 5.70, 6.52, and 7.26 kg) and final body weight (BW) (18.2, 19.8, 23.0, and 25.1 kg) increased (linear, P < 0.001). Increasing the weaning age reduced (linear, P < 0.001) the prevalence of pigs exhibiting belly nosing (27.6%, 15.0%, 6.5%, and 1.4%) during the first 3 wk. The percentage of pigs losing weight during the first week after weaning (35.1%, 28.7%, 12.4%, and 9.2%) decreased (linear, P < 0.001) as weaning age increased. Average daily gain (ADG; 295, 320, 374, 406 g/d) and average daily feed intake (493, 534, 619, 661 g/d) increased (linear, P < 0.001), while feed efficiency (G:F) (596, 599, 604, and 615) tended to increase (linear, P = 0.081) with weaning age. Removal rate (8.01%, 3.79%, 2.29%, and 1.65%) declined (linear, P = 0.001) as weaning age increased, while there was no evidence of difference (P = 0.463) in mortality rate (0.71%, 0.36%, 0.96%, 1.04%). In the finishing period, BW at 136 d post-weaning (114.9, 117.8, 124.7, and 126.5 kg) and ADG (1.02, 1.04, 1.08, and 1.07 kg/d) improved (linear, P < 0.001). There was no evidence of differences (P > 0.24) in removal (1.5%, 2.4%, 1.0%, and 0.0%) or mortality rates (0.9%, 1.0%, 1.0%, and 1.4%) with changes in weaning age. When performance was analyzed at a common day of life (164 d of age), no effects of weaning age (P > 0.25) were found for BW (125.2, 124.4, 128.0, and 126.5 kg) and lifetime ADG (growth rate from birth to market) (754, 751, 774, and 762 g/d). The BW sold per pig weaned increased (linear, P < 0.001) with weaning age. Even though the slope indicated a linear response, the magnitude of improvement was high until 25 d, before exhibiting diminishing returns from 25 to 28 d. Thus, the study suggests that increasing the weaning age can be an effective strategy to improve the overall performance in a commercial system. Although lifetime performance was not affected by the weaning age range studied, the consistent effect in the nursery and the increment in the number of pigs reaching the market facilitated by the improvement in the removal rate in the nursery phase imply that 25 d is the optimal weaning age.

Feeding level and diet type during the wean-to-estrus interval on the reproductive performance of sows / Efeito da quantidade e tipo de dietas durante o intervalo desmame-estro sobre o desempenho reprodutivo de matrizes suínas

ABSTRACT: This study was conducted to evaluate how the amount and type of diet consumed during the wean-to-estrus interval (WEI) affects reproductive performance and WEI duration in sows. A total of 542 sows were distributed into the following treatment groups based on a 2 × 2 factorial design: feed amount during WEI (2.75 or 3.75 kg/day) and diet (gestation [G] or lactation [L]) groups. Dietary treatments were as follows: high supply of G diet (GH), low supply of G diet (GL), high supply of L diet (LH), and low supply of L diet (LL). Sows were randomly allocated to groups according to their body score Caliper and birth order. There was an interaction (P < 0.05) between the factors for WEI duration, which was 0.2 days shorter in the GH and LL groups than in the other groups. No difference was observed between treatments (P>0.05) for the birth rate, total births, stillbirths, or total litter weight. There was a trend (P<0.10) toward a higher rate of live births in sows fed with G diet and sows receiving a low diet supply, with an average of 91.95% for both groups. In addition, there was a positive trend (P < 0.10) for live weight of the litter, where GH and LL treatments resulted in higher birth weight (17.9 and 17.7 kg, respectively) than other treatments. In conclusion, a supply of 3.75 kg/day or the use of a more energetic feed (lactation) during the WEI did not improve the reproductive performance of the subsequent cycle of sows in good body condition.

RESUMO: Este experimento foi conduzido com o objetivo de avaliar os efeitos da quantidade e tipo de dieta consumida durante o intervalo desmame-estro (IDE) sobre o desempenho ao parto subsequente e tempo de IDE de fêmeas suínas. Foram utilizadas 542 fêmeas, distribuídas em um delineamento fatorial 2×2 com duas quantidades de alimento fornecido durante o IDE (2,75 ou 3,75 kg/dia) e dois tipos de dieta (gestação - G ou lactação - L), sendo: Alto fornecimento de dieta G (GA), menor fornecimento de G (GM), alto fornecimento de L (LA) e menor fornecimento de L (LM). As fêmeas foram aleatoriamente distribuídas entre os tratamentos em blocos de acordo com o escore corporal Caliper e ordem de parto. Houve interação para tempo de IDE (P<0,05) entre a quantidade de ração e o tipo da dieta consumida durante o período, o qual foi 0,2 dias mais curto nos grupos GA e LM. Não houve diferença entre os tratamentos (P>0,05) sobre a taxa de parto, total de nascidos, natimortos e peso total da leitegada. Houve uma tendência para maior taxa de nascidos vivos (P<0,10) nas fêmeas que consumiram a dieta G, e nas fêmeas que receberam o menor fornecimento de ração, com média de 91,95%, para ambos os fatores. Além disso, foi observada tendência positiva (P<0,10) para o peso vivo da leitegada, em que GA e LM apresentaram maior peso ao nascer (17,9 e 17,7 kg, respectivamente). Em conclusão, o fornecimento de 3,75 kg/dia, ou o uso de uma dieta mais energética (lactação) durante o IDE, não melhora o desempenho reprodutivo do ciclo subsequente de fêmeas suínas em boa condição corporal.

Maternal nutrition during early and late gestation in gilts and sows under commercial conditions: impacts on maternal growth and litter traits1.

The effects of two different feeding levels, offered in two phases during gestation, on body measurements and litter traits were evaluated in 152 gilts and 551 sows. The treatments consisted of the combination of two gestation phases (phase 1-days 22 to 42; phase 2-days 90 to 110) and two feed amounts (1.8 or 3.5 kg/d). Females were weighed on days 22, 42, 90, and 110 of gestation. Born alive and stillborn piglets were weighed within 12 h of birth. Total placental efficiency (ratio between litter weight and total placental weight) was measured in 518 females. Variables concerning body measurements at days 42 and 90 of gestation were analyzed considering the effects of feed amount, parity order (PO) and its interaction as a 2 × 2 factorial arrangement. Body measurements at day 110 of gestation and litter traits were analyzed considering the effects of feed amounts in phase 1, feed amounts in phase 2, PO and their interactions, as a 2 × 2 × 2 factorial arrangement. As expected, BW, backfat, and caliper units were greater at days 42, 90, and 110 (P ≤ 0.006) for females fed 3.5 kg/d during the previous phase than those fed 1.8 kg. No differences were observed among feed levels in total number of piglets born, mummified fetuses, sum of born alive and stillborn piglets, and within-litter birth weight CV (P ≥ 0.118). The percentage of stillborn piglets was affected by a three-way interaction (feed level at phase 1 × feed level at phase 2 × PO). Gilts fed 1.8 kg/d at phase 1 and 3.5 kg/d at phase 2 had fewer stillborn piglets than the other females (P ≤ 0.004). Birth weight was not affected by feed levels (P ≥ 0.153); however, sows had heavier piglets than gilts (P < 0.001). Females fed 3.5 kg/d during phase 2 tended to have heavier litters (P = 0.054) than those fed 1.8 kg/d. Feeding a high level at phase 2 reduced the occurrence of lightweight piglets in gilts, but not in sows (feed level phase 2 × PO; P = 0.031). Total placental weight, average placental weight, and total placental efficiency were not affected by feed level at phase 1, feed level at phase 2 or interactions (P > 0.14). Sows had total placental weight and average placental weight greater (P ≤ 0.003) than gilts. In conclusion, increasing feed intake during phase 1, phase 2, or both phases resulted in increased maternal BW gain, without expressive effects on litter traits. Feeding 3.5 kg/d to gilts during phase 2 reduced the occurrence of lightweight piglets.

Effects of standardized total tract digestible phosphorus on growth performance of 11- to 23-kg pigs fed diets with or without phytase1,2.

Two experiments were conducted to determine the standardized total tract digestible phosphorus (STTD P) requirement for 11- to 23-kg nursery pigs fed diets with or without phytase. A total of 1,080 and 2,140 pigs (PIC 359 × Camborough, Hendersonville, TN; initially 11.4 ± 0.29 and 11.1 ± 0.24 kg) were used in Exp. 1 and Exp. 2, respectively. There were 23 to 27 pigs per pen with 6 and 12 replicate pens per treatment in Exp. 1 and Exp. 2, respectively. After weaning, pigs were fed a common pelleted diet with 0.45% STTD P for 7 d, and a common phase 2 meal diet with 0.40% STTD P for 14 d in Exp. 1 and 18 d in Exp. 2. Pens of pigs were then allotted to dietary treatments in a randomized complete block design with body weight (BW) as the blocking factor. In Exp. 1, dietary treatments consisted of 0.26%, 0.30%, 0.33%, 0.38%, 0.43%, 0.48%, and 0.53% STTD P. Treatments were achieved with the inclusion of monocalcium phosphate at the expense of corn. In Exp. 2, diets contained 1,000 phytase units (FYT; Ronozyme Hiphos 2500, DSM Nutritional Products, Inc., Parsippany, NJ) with assumed release value 0.132% STTD P, and treatments consisted of 0.30%, 0.33%, 0.38%, 0.43%, 0.48%, 0.53%, and 0.58% STTD P. These STTD P concentrations included the expected phytase release of 0.132% STTD P. In both experiments, a similar 1.17:1 Ca:P ratio was maintained across treatments. Statistical models included linear model (LM), quadratic polynomial (QP), broken-line linear (BLL), and broken-line quadratic (BLQ). In Exp. 1, increasing STTD P increased (linear, P < 0.001) ADG, ADFI, G:F, final BW, and grams of STTD P intake per day and per kilogram of gain. There was also a marginal quadratic response for G:F (P < 0.066). In Exp. 2, ADG and G:F increased quadratically (P < 0.05), whereas ADFI increased linearly (P = 0.060) with increasing STTD P. The BLL and QP model provided similar fit to G:F in Exp. 1, estimating the requirement for maximum G:F at 0.34% and 0.42%, respectively. The BLL was the best fitting model for ADG and G:F in Exp. 2, estimating the breakpoint at 0.40% and 0.37% STTD P, respectively. The BLL and BLQ models estimated the breakpoint for ADG as a function of STTD P intake in grams per day at 2.92 and 3.02 g/d, respectively. These data provide empirical evidence that for 11- to 23-kg pigs, the NRC (2012) accurately estimates the STTD P requirement on a g/d basis. As a percentage of the diet, the STTD P requirement for diets without or with 1,000 FYT added phytase ranged from 0.34% to 0.42%.

Standardized total tract digestible phosphorus requirement of 24- to 130-kg pigs1,2.

A study was conducted to determine the standardized total tract digestible phosphorus (STTD P) requirement for 24- to 130-kg finishing pigs housed under commercial conditions. A total of 1,130 barrows and gilts (PIC 359 × 1050, Hendersonville, TN; initially 24.2 kg) were used, with 26 to 27 pigs per pen with 7 replicates per treatment. Pens of pigs were allotted to treatments in a randomized complete block design with body weight (BW) as the blocking factor. The dietary treatments were fed in 4 phases and were formulated to contain 80%, 90%, 100%, 115%, 130%, and 150% of the National Research Council (NRC) requirement estimate for finishing pigs within each phase. Weight ranges for each phase were: 27 to 49, 49 to 76, 76 to 90, and 90 to 130 kg. Treatments were achieved by increasing the amount of monocalcium phosphate at the expense of corn in the diet with no added phytase. All diets were formulated to contain a similar 1.14:1 to 1.16:1 total Ca:P ratio across treatments in all phases. Increasing STTD P resulted in a quadratic response (P < 0.05) in average daily gain (ADG), gain-to-feed ratio (G:F), and final BW. The greatest improvement was observed with STTD P at 130% of NRC for ADG and final BW and at 115% STTD P for G:F. Average daily feed intake increased linearly (linear, P < 0.05) with the inclusion of STTD P. Increasing STTD P resulted in an increase (quadratic, P < 0.05) in hot carcass weight (HCW) and carcass ADG with the greatest response observed with STTD P at 130% of NRC. There was a marginally significant response (quadratic, P < 0.10) in carcass G:F, with the greatest improvement with STTD P at 115% of NRC. Carcass yield decreased (linear, P < 0.05) with increasing STTD P, while there was a marginally significant (linear, P < 0.10) decrease in backfat and increase in fat-free lean. At the end of the study, a metacarpal was collected and analyzed for bone ash. Increasing STTD P resulted in an increase (linear, P < 0.05) in bone ash weight and percentage ash. For ADG and G:F, the quadratic model demonstrated the best fit. The maximum response in ADG and G:F was estimated at 122% and 116% of NRC STTD P, respectively. The broken-line linear model best fit the data for percentage bone ash, with a plateau achieved at 131% of the NRC STTD P. In conclusion, the estimated STTD P requirement of 24 to 130 kg ranged from 116% to 131% of the NRC publication (2012) requirement estimate.

Calcium to phosphorus ratio requirement of 26- to 127-kg pigs fed diets with or without phytase1,2.

Two experiments were conducted to determine the effects of calcium to phosphorus (Ca:P) ratio in diets adequate in standardized total tract digestible (STTD) P on performance of 26- to 127-kg pigs fed diets with or without phytase. Pens of pigs (n = 1,134 in Exp. 1 and n = 1,215 in Exp. 2, initially 26.3 and 25.3 kg) were blocked by body weight (BW) and allotted to treatments in a randomized complete block design. There were 27 pigs per pen with 7 and 9 replicates per treatment in Exp. 1 and Exp. 2, respectively. Treatments were formulated to contain 0.75:1, 1.00:1, 1.25:1, 1.50:1, 1.75:1, and 2.00:1 analyzed Ca:P ratios in Exp. 1, and 0.75:1, 1.00:1, 1.25:1, 1.50:1, and 2.00:1 analyzed Ca:P ratios in Exp. 2. These correspond to a range of 0.96:1 to 2.67:1 and 0.95:1 to 2.07:1 STTD Ca:STTD P ratios in Exp. 1 and Exp. 2, respectively. Experiment 2 diets contained 1,000 phytase units of Ronozyme HiPhos 2500 (DSM Nutritional Products, Inc., Parsippany, NJ) with release values of 0.132% STTD P, 0.144% total Ca, and 0.096% STTD Ca. Diets contained 122% of NRC (2012) STTD P estimates for the weight range across 4 phases. In Exp. 1, increasing Ca:P ratio increased (quadratic, P < 0.05) average daily gain (ADG) and average daily feed intake (ADFI). Feed efficiency (G:F) worsened (quadratic, P < 0.05) at the highest ratio. Hot carcass weight (HCW) and bone ash increased (quadratic, P < 0.05) while carcass yield decreased (linear, P < 0.10) with increasing Ca:P ratio. The maximum responses in ADG, HCW, and bone ash were estimated at 1.38:1, 1.25:1, and 1.93:1 analyzed Ca:P and at 1.82:1, 1.64:1, and 2.57:1 STTD Ca:STTD P, respectively. In Exp. 2, increasing Ca:P ratio increased (quadratic, P < 0.05) ADG and bone ash, and improved G:F (linear, P < 0.05). There was a quadratic increase (P < 0.05) in HCW and decrease in carcass yield (P < 0.10). The maximum responses in ADG, HCW, and bone ash were estimated at 1.63:1, 1.11:1 to 1.60:1, and 1.25:1 analyzed Ca:P and at 1.75:1, 1.28:1 to 1.71:1, and 1.40:1 STTD Ca:STTD P, respectively. Expressing ADG on a STTD Ca:STTD P basis provided a more consistent estimate of the ideal Ca:P ratio among the 2 studies than analyzed Ca to analyzed P ratio. A STTD Ca:STTD P ratio between 1.75:1 to 1.82:1 can be used for 26- to 127-kg pigs that are fed diets adequate in STTD P with or without added phytase to maximize growth rate without reducing bone ash.

Evaluation of the optimal standardized ileal digestible valine:lysine ratio in lactating sow diets1.

An experiment was conducted with 430 sows to evaluate the ideal standardized ileal digestible (SID) Val:Lys on sow and litter performance during an 18.6-d lactation period. The SID Val:Lys ratios measured were based on the previously published literature and then values above and below reported values. Sows were randomly allotted within parity block (parity 1, parity 2, and parity 3+) to one of five corn-soybean meal-based lactation diets formulated to contain different levels of SID Val:Lys (0.50, 0.62, 0.75, 0.88, and 1.00, respectively). All diets were formulated to be isocaloric (3.35 ME Mcal/kg) with 0.95% SID Lys and contained vitamins and minerals that exceeded recommendations (NRC, 2012). Experimental diets were given to sows from 112 d of pregnancy throughout the 23-d lactation period. Litters were standardized within 48 h after farrowing. Sows were fed with the Howema computerized feeding system that mixed the high and low diets to create the intermediate diets, weighed the feed for each sow and then delivered the feed to each individual feeding hopper to record daily sow feed intake during lactation. Data were analyzed as a randomized complete block design using the PROC MIXED procedure of SAS with sow as the experimental unit and treatment as a fixed effect and parity as the random effect. Results were considered significant at P ≤ 0.05 and considered a trend at P > 0.05 and P ≤ 0.10. Sow ADFI was not significantly different (5.2, 5.2, 5.2, 5.0, and 5.4 ± 0.15 kg/d, respectively). On average, sows consumed ~45 g of SID Lys per day. Sow wean to estrus (5.2, 4.7, 5.3, 5.5, and 4.5 ± 0.32 d, respectively) was not different as the Val:Lys ratio changed. Increasing the Val:Lys ratio resulted in no differences (2.66, 2.64, 2.76, 2.61, and 2.62 ± 0.08 kg; P > 0.10) in average daily litter gain. There were no differences in sow weight loss or subsequent total born across the dietary treatments. Overall, increasing levels of SID Val:Lys did not change sow reproductive performance or piglet growth rate.

Impact of feed intake during late gestation on piglet birth weight and reproductive performance: a dose-response study performed in gilts.

The effects of increasing feed intake (1.8, 2.3, 2.8, and 3.3 kg/d) during late gestation of gilts on piglet birth weight and female reproductive performance were evaluated. A total of 977 gilts were fed a diet based on corn-soybean meal (3.29 Mcal ME per kg and 0.64% standardized ileal digestible lysine) from day 90 of gestation until farrowing. Gilts were weighed on days 90 and 112 of gestation, at farrowing and weaning. Born alive and stillborn piglets were weighed within 12 h of birth. Colostrum yield (CY), lactation feed intake, and litter growth rate were measured in a randomly selected subsample of 245 gilts. The data were analyzed using generalized linear mixed models. As expected, gains in body weight (BW) were different at day 112 (P < 0.001) with the greatest values observed in the 3.3 kg/d treatment. As feed intake increased during late gestation, BW, body condition score (BCS), backfat (BF), and Caliper unit also increased between day 112 and weaning (P < 0.001). No differences were found among treatments in total number of piglets born, mummified fetuses, sum of born alive and stillborn piglets, and within-litter birth weight CV (P > 0.05). Tendencies for quadratic effect of feed intake were observed for born alive piglets (P = 0.079), average birth weight of piglets (P = 0.083), and litter weight (P = 0.059). Gilts with lower feed intake during late gestation had reduced percentages of stillborn piglets than gilts with greater feed intakes. The CY decreased linearly (P < 0.05) as the feed intake was increased. No differences among treatments were found at weaning in individual piglet weight and litter weight, as well as in percentage of weaned piglets (P > 0.05). Lactation feed intake decreased as gestation feeding level increased (P < 0.05). No differences in the subsequent cycle were observed among treatments for farrowing rate, retention rate up to the next farrowing, number of total piglets born, born alive, stillborn piglets, and mummified fetuses (P > 0.05). In conclusion, increased feed intake from day 90 of gestation until farrowing resulted in increased maternal BW gain and stillborn rate, but reduced CY and lactation feed intake. A slight increase in birth weight was observed for the 2.3 kg/d treatment. Furthermore, litter growth and subsequent female reproductive performance were not affected by feed intake during late gestation.