Impact of high-energy diets on the rumen environment and digital cushion in confined cattle

ABSTRACT: This study aimed to identify gross and microscopic changes, caused by high-energy diets, in the rumen environment and hoof of confined beef cattle. The study sample comprised 40 confined heifers (Bos taurus) with no disease history divided into four experimental groups using different diets: Group 1 (D1, control), 48:52 forage:concentrate ratio; Group 2 (D2), 30:70 forage:concentrate ratio; Group 3 (D3), 30:70 forage:concentrate ratio + sucrose; Group 4 (D4), 100% concentrate. All animals underwent clinical examination, assessment of ruminal fluid pH and lameness, and sample collection after slaughter for histopathology of the hoof laminae and digital cushion and ruminal tissue. All dependent variables of the study were compared using the SPSS 20.0 statistical software. The variables that did not show normality (HR, RM, ST, and CRT) were compared with application of the Kruskal-Wallis test followed by the Dunnet’s multiple comparison test. All other variables were submitted to analysis of variance (ANOVA) followed by Tukey’s test. The different diets had an impact on the rumen environment (p<0.05) of the heifers assessed, with momentary general depression in the first 12 h after sucrose induction (D3), as well as mild clinical signs in D4. The animals in D3 and D4 presented lower motility (p<0.05) and ruminal pH (p<0.01) than those in D1. Of the 40 heifers, 27.5% (n=11) showed gross lesions in the epithelium of ruminal pillars, whereas 22.5% (n=9) of those in D3 and D4 presented these lesions. Sole corium thickness varied between heifers in D3 compared with those in D1 and D2 (p<0.05). Therefore, high-energy diets, as used in this study, alter some clinical parameters and the rumen environment, causing lesions in the rumen mucosa, and of lesser intensity, in the hoof corium and laminae, suggestive of laminitis.

Characteristics of the non-carcass components of steers fed different sources of dietary carbohydrates

We evaluated the characteristics of the non-carcass components of 24 steers (Charolais × Nelore) fed different carbohydrate sources (ground corn, soybean hulls, or wheat bran) in the diet. The animals were 353.2 kg and 22 months of age at early termination, and had been fed forage consisting of sorghum silage at a forage:concentrate ratio of 40.2:59.8. The carbohydrate sources had no effect on the weights of the carcass, vital organs, and blood. The absolute weights of the intestines and rumen fat were higher (P < 0.05) in animals fed corn than in those fed soybean hulls or wheat bran (10.87 vs. 8.89 and 8.87 kg and 5.26 vs. 4.12 and 3.64 kg, respectively). The same pattern was observed when these organs weights were adjusted for empty body weight. The weight of the omasum was highest (P < 0.05) in the wheat bran-fed animals (6.02 vs. 4.70 and 5.49 kg in the corn- and soybean hull-fed animals, respectively). Animals fed soybean hulls had a higher absolute weight of kidney fat (1.6 kg) than steers receiving wheat bran (1.06 kg) or corn (0.79 kg). Wheat bran gave the highest leg weight compared with corn and soybean hulls (2.46 vs. 2.22 and 2.23 kg per 100 kg of empty body weight, respectively).

Animal nutrition strategies to reduce greenhouse gas emissions in dairy cattle

The objective of this study was to analyze different animal nutrition strategies from published papers to reduce greenhouse gas (GHG) emissions, particularly methane (CH4) and nitrous oxide (N2O) in dairy cattle. Ration data used (n = 32 diets) was obtained from 15 published papers selected according to differences between forage:concentrate ratio and crude protein (CP) content. An empirical model was used to estimate enteric methane emissions based on fiber and CP content in the diets. The N2O emission was calculated according to Intergovernmental Panel of Climate Change (IPCC) recommendations. Differences between CH4 and N2O affected by FC or CP content were analyzed through a variance analysis. Furthermore, a correlation analysis was carried out to compare CP content and nitrogen excretion in feces, urine and milk. Estimations of enteric CH4 were not significantly different between diets with various forage content levels. Diets with high concentrate content had lower GHG intensity. Nitrogen excretion in feces and urine increased linearly as dietary protein level was increased from the lowest to the highest concentrations, but conversion of nitrogen intake to nitrogen excreted in milk was not affected by increasing dietary protein. In conclusion, dietary manipulation could decrease GHG emissions by unit of produced milk.

Growth performance of finishing feedlot lambs fed maize silage inoculated with Bacillus subtilis and lactic acid bacteria

Whole-crop maize forage was ensiled without inoculant (control), inoculated with Lactobacillus buchneri and L. plantarum at a rate of 1 × 105 cfu/g fresh forage per bacterium (LBLP), or inoculated with Bacillus subtilis and L. plantarum at a rate 1 × 105 cfu/g fresh forage per bacterium (BSLP) with the goal to investigate the growth performance of finishing feedlot lambs. Thirty Dorper × Santa Ines lambs (29 ± 3.5 kg initial body weight) were used in the feedlot programme and assigned (n = 10) to one of three diets containing control, LBLP or BSLP silages in a 60:40 forage:concentrate ratio. Inoculation of maize silage did not alter dry matter intake (overall mean = 1.16 kg/day) and average daily gain (overall mean = 0.217 kg/day) of lambs. Consequently, feed efficiency remained unchanged. Inoculation of maize silage did not alter carcass and meat traits of lambs, with the exception of meat colour, wherein yellowness (b*) decreased by feeding LBLP and BSLP diets compared with the untreated diet. Regarding ruminal fermentation, there was an interaction between diets and the interval at which ruminal fluid was sampled for determining total volatile fatty acid concentration, but inoculation yielded no obvious results. In conclusion, the use of diets based on maize silage inoculated with L. plantarum combined with either L. buchneri or B. subtilis did not display relevant effects on growth performance of lambs; this response might be related to the limited impact of these bacterial inoculants on silage composition.

Diet-induced milk fat depression is associated with alterations in ruminal biohydrogenation pathways and formation of novel fatty acid intermediates in lactating cows

The biohydrogenation theory of milk fat depression (MFD) attributes decreases in milk fat in cows to the formation of specific fatty acids (FA) in the rumen.Trans-10,cis-12-CLA is the only biohydrogenation intermediate known to inhibit milk fat synthesis, but it is uncertain if increased ruminal synthesis is the sole explanation of MFD. Four lactating cows were used in a 4×4 Latin square with a 2×2 factorial arrangement of treatments and 35-d experimental periods to evaluate the effect of diets formulated to cause differences in ruminal lipid metabolism and milk fat synthesis on the flow of FA and dimethyl acetal at the omasum. Treatments comprised total mixed rations based on grass silage with a forage:concentrate ratio of 35:65 or 65:35 containing 0 or 50 g/kg sunflower oil (SO). Supplementing the high-concentrate diet with SO lowered milk fat synthesis from −20·2 to −31·9 % relative to other treatments. Decreases in milk fat were accompanied by alterations in ruminal biohydrogenation favouring thetrans-10 pathway and an increase in the formation of specific intermediates includingtrans-4 totrans-10-18 : 1,trans-8,trans-10-CLA,trans-9,cis-11-CLA andtrans-10,cis-15-18 : 2. Flow oftrans-10,cis-12-CLA at the omasum was greater on high- than low-concentrate diets but unaffected by SO. In conclusion, ruminaltrans-10,cis-12-CLA formation was not increased on a diet causing MFD suggesting that other biohydrogenation intermediates or additional mechanisms contribute to the regulation of fat synthesis in the bovine mammary gland.

Performance and carcass characteristics of cattle fed lipid sources in the diet

The aim of this study was to determine the effect of the inclusion of different lipid sources [whole cottonseed (CS) and protected fat in diets containing sugarcane, corn, citrus pulp, CS meal, and urea] on animal performance, hot carcass dressing (HCD), ribeye area (RA), fat thickness (FT), and postmortem pH of the meat of Nellore cattle during finishing. The treatments evaluated were feed with 2.50% CS (control diet, T1 treatment); feed with 11.50% CS (high CS, T2 treatment); and feed with 3.13% CS added of protected lipid (PL) (T3 treatment), all on a DM basis. The forage:concentrate ratio of the diet was 50:50. Thirty-nine intact steers with average initial body weight of 494 kg and 36 months old were confined for 63 d. The addition of lipid sources tested in this study did not affect dry matter intake, crude protein intake, neutral detergent fiber intake, final live weight, average daily weight gain, HCD, RA, FT, and meat pH. It was concluded that the addition of PLs in the diet did not affect weight gain and carcass characteristics.

Metabolic profile of lactating goats fed integral mango meal

SUMMARY The work was conducted to evaluate the metabolic profile of lactating goats fed diets containing integral mango meal as a replacement for corn. Four levels of replacement (0, 33, 66 and 100%) were evaluated in diets with forage:concentrate ratio of 60:40. Eight crossbred multiparous lactating Saanen goats (48.72 ± 1.99 kg of BW) were introduced in the experiment 48 days postpartum and maintained up to 124 days of lactation. It was used a double Latin Square (4x4) experimental design, with four treatments, four periods and four animals per square. There was no effects (P>0.05) for the integral mango meal level on the intake of DM (1890 g/day), CP (278 g/day) and NDF (959 g/day). However, the intake of NFC and TDN decreased (P<0.05) 27.9 g/day and 0.082 kg/day, respectively, as the dietary integral mango meal increased. The concentrations of urea, creatinine, gamma glutamyl transferase, aspartate aminotransferase, albumin, total protein, glucose, triglycerides, total cholesterol, and magnesium were not altered (P>0.05) by replacement levels, with average values of 54.52 mg/dl, 0.71 mg/dl, 52.59 UI, 77.37 UI, 4.69 g/dl, 9.32 g/dl, 74.44 mg/dl, 40.10 mg/dl, 39.39 mg/dl, and 11.09 mg/dl, respectively. Considering the metabolic profile, mango meal whole can totally replace corn in diets of dairy goats.