Short-term effects of soybean oil supplementation on performance, digestion, and metabolism in dairy cows fed sugarcane-based diets

We aimed to quantify the productive and metabolic responses, and digestive changes in dairy cows fed various concentrations of soybean oil (SBO) in high-concentrate, sugarcane-based diets. Eight rumen-cannulated multiparous Holstein cows in mid lactation (574 ± 19.1 kg of body weight and 122 ± 6.9 d in milk), averaging 22.5 ± 1.22 kg/d of milk were assigned to replicated 4 × 4 Latin squares. The experimental period lasted 21 d as follows: 14 d for adaptation, followed by a sampling period from d 15 to 21. The diets were formulated with increasing concentrations of SBO [% of dry matter (DM)]: control (0%), low (LSBO; 1.57%), medium (MSBO; 4.43%), and high (HSBO; 7.34%). Dry matter intake decreased quadratically in response to SBO addition. The greatest decrease in DM intake was observed in MSBO and HSBO diets. Both milk and energy-corrected milk yield were quadratically affected by the SBO inclusion, with a slight decrease up to MSBO and substantial decrease in the HSBO diet. The milk fat concentration linearly decreased from 3.78% in the control to 3.50% in the HSBO diet. The potentially digestible neutral detergent fiber digestibility in the rumen decreased from 55.7% in the control to 35.2% in the HSBO diet. The fractional rate of digestion of potentially digestible neutral detergent fiber in the rumen decreased linearly from 3.13 to 1.39%/h from the control to HSBO diet. The fractional rate of indigestible neutral detergent fiber passage in the rumen was quadratically affected, with the lowest value (2.25%/h) for the HSBO diet. Rumen pH increased from 6.42 to 6.67, and ammonia nitrogen decreased from 28.1 to 21.4 mg/dL, in the control and HSBO diets, respectively. Rumen volatile fatty acids decreased quadratically, with the greatest decrease observed in MSBO and HSBO diets. Serum concentrations of glucose, fatty acids, and β-hydroxybutyrate were unaffected by SBO inclusion. However, serum concentrations of total cholesterol and high- and low-density lipoproteins linearly increased with increasing concentrations of SBO in the diet. Inclusion of SBO at concentrations from 4.43 to 7.34% of the diet DM decreased DM intake, energy-corrected milk production, fiber digestibility, and rumen fermentation and was thus not recommended. Soybean oil supplementation at 1.57% of the diet DM proved to be a safe concentration for dairy cows fed high-concentrate diets with sugarcane as the sole forage

Effects of rumen undegradable protein on intake, digestibility and rumen kinetics and fermentation characteristics of dairy heifers

The aim of this work was to evaluate the influence of increasing amounts of rumen undegradable protein (RUP) on intake, nutrient digestibility, rumen kinetics and fermentation characteristics and N use efficiency of dairy Holstein heifers. Eight rumen-cannulated Holstein heifers (initial body weight 276 ± 8.3 kg) were used in a replicate 4 × 4 Latin square design with four dietary RUP amounts in the total dietary protein, as follows: 38% of RUP (38RUP), 44% of RUP (44RUP), 51% of RUP (51RUP) and 57% of RUP (57RUP). The experimental period was 84 days, subdivided into four periods of 21 days (14 days for adaptation + 7 days for collections). Eight spot collections of faeces, urine, ruminal content and omasal digesta were performed at 9-h intervals, as follows: on 15th day samples were collected at 0600 h and 1500 h; on 16th day samples were collected at 0000 h, 0900 h and 1800 h; on 17th day samples were collected at 0300 h, 1200 h and 2100 h. Two complete rumen evacuations were performed: one on 19th day 4 h after morning feeding and another on 21st day immediately before morning feeding. Total (kg/day) and relative (g/kg of body weight) intake of dry matter, crude protein (CP), neutral detergent fibre corrected for ash and protein were not affected (P >  0.10) by dietary RUP amounts. Ruminal (P =  0.06) and intestinal (P =  0.09) digestibilities of CP presented a tendency to decrease with increasing RUP. There were no effects of dietary RUP amounts (P >  0.10) on the rates of ingestion, passage and digestion (%/h) as well on the total volatile fatty acid concentration in the rumen. Urinary N excretion presented a tendency (P =  0.08) to decrease with increasing RUP. In addition, retained N presented a tendency (P =  0.09) to increase according to dietary RUP amounts and greater values were observed for treatments 51RUP and 57RUP. Microbial protein synthesis, microbial efficiency and the efficiency of use of N for microbial synthesis decreased with increasing RUP (P <  0.05). Metabolisable protein flow presented a tendency to increase (P =  0.091) and greater values were observed for 51RUP and 57RUP. In general, urinary N excretion decreased, while the flow of metabolisable protein and RUP increased with increasing RUP levels. As a consequence of this pattern, the treatments 51RUP and 57RUP presented increases in the retained N

Molecular Factors Underlying the Deposition of Intramuscular Fat and Collagen in Skeletal Muscle of Nellore and Angus Cattle

<div><p>Studies have shown that intramuscular adipogenesis and fibrogenesis may concomitantly occur in skeletal muscle of beef cattle. Thus, we hypothesized that the discrepancy of intramuscular fat content in beef from Nellore and Angus was associated with differences in intramuscular adipogenesis and fibrogenesis during the finishing phase. To test our hypothesis, longissimus muscle samples of Nellore (<i>n</i> = 6; BW = 372.5 ± 37.3 kg) and Angus (<i>n</i> = 6; BW = 382.8 ± 23.9 kg) cattle were collected for analysis of gene and protein expression, and quantification of intramuscular fat and collagen. Least-squares means were estimated for the effect of Breed and differences were considered at <i>P</i> ≤ 0.05. A greater intramuscular fat content was observed in skeletal muscle of Angus compared to Nellore cattle (<i>P</i>≤0.05). No differences were observed for mRNA expression of lipogenic and lipolytic markers <i>ACC</i>, <i>FAS</i>, <i>FABP4</i>, <i>SERBP–1</i>, <i>CPT–2</i>, <i>LPL</i>, and <i>ACOX</i> (<i>P</i> > 0.05) in skeletal muscle of Nellore and Angus cattle. Similarly, no differences were observed in mRNA expression of adipogenic markers <i>Zfp423</i>, <i>PPARγ</i>, <i>and C/EBPα</i> (<i>P</i>>0.05) However, a greater PPARγ protein content was observed in skeletal muscle of Angus compared to Nellore cattle (<i>P</i>≤0.05). A greater abundance of adipo/fibrogenic cells, evaluated by the PDGFRα content, was observed in skeletal muscle of Angus than Nellore cattle (<i>P</i>≤0.05). No differences in fibrogenesis were observed in skeletal muscle of Angus and Nellore cattle, which is in accordance with the lack of differences in intramuscular collagen content in beef from both breeds (<i>P</i>>0.05). These findings demonstrate that difference in intramuscular fat content is associated with a slightly enhanced adipogenesis in skeletal muscle of Angus compared to Nellore cattle, while no difference in fibrogenesis.</p></div

Performance and carcass traits of Angus and Nellore cattle.

<p>Performance and carcass traits of Angus and Nellore cattle.</p

Abundance of PDGFR_<i>α</i> in skeletal muscle of Angus and Nellore cattle.

<p>Quantification of PDGFR_<i>α</i> by western-blot using tubulin as a loading control as an indicator of the abundance of mesenchymal progenitor cells. Differences were considered at <i>P</i> ≤ 0.05 (*).</p