Effect of fiber source and crude protein level on nursery pig performance and fecal microbial communities

Evaluating increasing levels of sodium diformate in diets for nursery and finishing pigs on growth performance, fecal dry matter, and carcass characteristics

Two studies were conducted to evaluate the effects of sodium diformate in swine diets. For Exp. 1, 360 barrows (DNA 200 × 400; initially 5.9 ± 0.06 kg) were used in a 38-d study. At weaning, pigs were randomly assigned to pens with five pigs per pen. Each pen was allocated to one of six treatments with 12 pens per treatment. Treatments were formulated to provide none, 0.40%, 0.60%, 0.80%, 1.00%, or 1.20% sodium diformate added at the expense of corn. Diets were fed in three phases: phase 1 from weaning to day 9, phase 2 from days 9 to 24, and phase 3 from days 24 to 38. From days 0 to 24 (phases 1 and 2), increasing sodium diformate increased (linear, P = 0.001) gain-to-feed (G:F). However, sodium diformate did not affect average daily gain (ADG) or average daily feed intake (ADFI). From days 24 to 38 (phase 3) and overall (days 0 to 38), there was no evidence of differences due to increasing sodium diformate for any growth response criteria. There was no evidence for differences in fecal dry matter (DM) on day 9. However, fecal DM decreased (linear, P < 0.05; quadratic, P = 0.097) as sodium diformate increased on day 24. In Exp. 2, 2,200 pigs (Duroc sire [PIC 800 or DNA 600] × PIC Camborough; initially 24.2 ± 0.30 kg) were used in a 117-d growth trial. Pens of pigs (25 pigs per pen) were randomly assigned to one of four treatments with 22 pens per treatment. Treatments were formulated with additions of none, 0.25%, 0.50%, or 0.75% sodium diformate. Diets were fed in six phases from 24 to 141 kg. For period 1 (days 0 to 32), ADFI tended to decrease then increase (quadratic, P = 0.081) with increasing sodium diformate, whereas G:F increased then decreased (quadratic, P < 0.001) with increasing sodium diformate. For period 2 (days 32 to 60), there was no evidence for differences in ADG or ADFI; however, there was a tendency for G:F to increase then decrease (quadratic, P = 0.093) with increasing sodium diformate. From days 60 to 93, increasing sodium diformate increased (linear, P < 0.01) ADG and ADFI. From days 93 to 117, increasing sodium diformate increased (linear, P < 0.05) ADG, ADFI, and G:F. Overall (days 0 to 117), pigs fed increasing sodium diformate had increased (linear, P < 0.01) ADG and a tendency for increased (linear, P = 0.075) ADFI; however, there was no evidence for differences in G:F. There were no treatment differences for any carcass characteristic. In summary, increasing sodium diformate may increase G:F in the early nursery and improve ADG after day 60 (approximately 82 kg) in the finishing period.

The Improvement of Semen Quality by Dietary Fiber Intake Is Positively Related With Gut Microbiota and SCFA in a Boar Model

Although fiber-rich diets have been positively associated with sperm quality, there have not been any studies that have examined the effects of dietary fiber and its metabolites on sperm quality in young or pre-pubescent animals. In this study, we aimed to explore the effect of dietary fiber supplementation on semen quality and the underlying mechanisms in a boar model. Sixty purebred Yorkshire weaning boars were randomly divided into the four groups (T1–T4). Groups T1, T2, and T3 boars were fed diets with different levels of fiber until reaching 160 days of age and were then fed the same diet, while group T4 boars were fed a basal diet supplemented with butyrate and probiotics. Compared with T1 boars, sperm motility and effective sperm number were significantly higher among T3 boars. Meanwhile, at 240 days of age, the acetic acid and total short-chain fatty acid (SCFA) contents in the sera of T3 and T4 boars were significantly higher than those in T1 boars. The abundance of microbiota in T2 and T3 boars was significantly higher than that in T1 boars (P < 0.01). Moreover, dietary fiber supplementation increased “beneficial gut microbes” such as UCG-005, Rumenococcus, Rikenellaceae_RC9_gut_group and Lactobacillus and decreased the relative abundance of “harmful microbes” such as Clostridium_sensu_stricto_1, Romboutsia and Turicibacter. Collectively, the findings of this study indicate that dietary fiber supplementation improves gut microbiota and promotes SCFA production, thereby enhancing spermatogenesis and semen quality. Moreover, the effects of dietary fiber are superior to those of derived metabolites.

Dietary Fibre Supplementation Improves Semen Production by Increasing Leydig Cells and Testosterone Synthesis in a Growing Boar Model

Testicular development is imperative to spermatogenesis, and pre-puberty is the key period for testis development. This study, therefore, investigated the effects of fibre supplementation on testis development and its possible mechanism in a growing boar model. Thirty Yorkshire boars were randomly divided into a control group (Control) and a fibre group (Fibre) from day 0 to 90 after weaning, with three pigs per pen and five pens per treatment. Blood and testes were collected for analysis. Dietary fibre supplementation had no significant effect on growth performance, testicular volume, or libido but increased the semen production of boars. Boars fed with fibre had lower serum cholesterol (CHO) and low-density lipoprotein (LDL) levels compared to those on the Control diet; however, testicular CHO, triglyceride (TG), and LDL concentration in the Fibre group were significantly higher than the Control group (P &lt; 0.01). Testicular histological analysis showed that seminiferous tubules and testicular germ cells of 120-day-old boars were densely arranged in the Fibre group, and the number of Leydig cells was significantly higher than that of the Control group (P &lt; 0.001). Furthermore, the diet supplemented with fibre significantly decreased leptin, leptin receptor (Leptor), and luteinising hormone (LH) concentrations in boar serum (P &lt; 0.05), whereas follicle-stimulating hormone (FSH) and testosterone concentrations were significantly increased (P &lt; 0.05). Meanwhile, the expression of AMH, AMHR2, and SYCP3 genes related to proliferation and differentiation, and hormone-related genes STAR and SOCS3, were significantly up-regulated (P &lt; 0.05). OCCLUDIN expression was up-regulated, whereas CDH2 expression was down-regulated. In conclusion, increased fibre intake during the pre-puberty period in growing boar is crucial for Leydig cell proliferation, up-regulating the expression of genes related to hormone synthesis and thereby promoting the secretion of testosterone and semen production.