The present study was intended to evaluate the effect of forage source (alfalfa hay; ALF vs. corn silage; CS) along with a supplemental fat source (soybean oil; SO vs. rumen-inert palm fatty acids; PF) on growth performance, nutrient digestibility, and ruminal fermentation in dairy calves. Forty-eight new-born Holstein female calves (3 d old) were assigned to one of 4 treatments: (1) alfalfa hay with soybean oil (ALF-SO); (2) alfalfa hay with palm fatty acids (ALF-PF); (3) corn silage with soybean oil (CS-SO); (4) corn silage with palm fatty acids (CS-PF). Starter diets had equal amounts of forage (100 g/kg dry matter; DM) and fat source (30 g/kg DM). Calves were fed a constant amount of milk (d 1 to 63) and had ad libitum access to water and starters (d 1 to 83). The lowest and greatest starter intakes during the preweaning period occurred in ALF-SO and CS-PF, respectively. This coincided with forage × fat source interaction for average daily gain (ADG) during preweaning. The forage source affected total DM intake and ADG over the entire period, body weight (BW) at weaning, and final BW with greater values in calves that received CS compared with ALF. The concentrations of total short-chain fatty acids and butyrate were increased, whereas concentration of acetate and acetate:propionate ratio were decreased in the rumen of calves fed CS compared with ALF. Feeding CS increased urinary excretion of allantoin and, as a trend, total purine derivatives (PD) and estimated microbial protein synthesis in comparison with ALF. The fat source affected starter intake, ADG, and BW postweaning with the highest values in PF. The digestibility of neutral detergent fiber, crude protein and, as a trend, organic matter were higher in calves fed PF compared with SO. Calves fed PF had lower ruminal ammonia-N concentration and urinary N excretion and greater urinary excretion of allantoin and total PD. Calves receiving SO had a lower ruminal protozoa population. In conclusion, supplementing starter diets with CS and PF is superior to ALF and SO. Interaction of the positive effects of CS and PF on performance underlines that concurrent supplementation of CS with PF is especially recommendable in young calves before weaning.

This study was conducted to investigate the effect of decreasing concentrations of dietary neutral detergent fiber (NDF) at high rumen undegradable protein (RUP) on performance, digestibility, chewing activity, blood attributes, and carcass characteristics in 32 weaned male Afshari lambs (90 days of age; 26 kg initial body weight; BW). Dietary metabolic energy (ME) was increased from 10.6–11.5 and 11.8 MJ/kg dry matter (DM) by replacing alfalfa hay with grain to achieve NDF concentrations of 270, 245, and 220 g/kg DM, respectively, at 66.6 g/kg DM of RUP. The control (CON) diet contained 10.9 MJ/kg ME, 270 g/kg NDF and 59.6 g/kg RUP on DM basis. Rations containedsimilar concentrations of crude protein (CP, 160 g/kg DM). Lambs were slaughtered after a 56-d feeding period. The increase in dietary RUP had no effect on BW and average daily gain (ADG) but tended to decrease apparent digestibility of CP and DM, significantlydecreasedplasma urea concentration, and increased carcass CP content. Other body or carcass characteristics were unchanged. Decreasing dietary fiber at high RUP did not result in adverse effects on BW, ADG, body length, withers height, apparent digestibility of DM and CP, and BFT, but decreased DM intake (1539 vs. 1706 g/d) and feed conversion ratio (FCR; 4.33 vs. 5.39) compared with CON. Gradual reduction in NDF and physically effective NDF did not affecteating, ruminating or chewing times. Plasma glucose concentration was greater for NDF220 than for the three other treatments (p = 0.015).Slaughtering traits were not affected by dietary treatment except for hot carcass weight, which increased in NDF220 and NDF245 compared with NDF270 (p = 0.021). The concentration of meat CP increased in NDF270 versus CON (167 vs. 152 g/kg). Quadratic effects occurred for meat ether extract concentration (highest in NDF220) and fat-tail weight (highest in NDF245). In conclusion, the results showed that increasing the proportion of RUP within dietary CP improves carcass protein accretion. Decreasing dietary NDF to 220 g/kg DM at high RUP does not impair eating behavior and improves FCR in 3-month-old fat-tailed lambs.

Many dairy producers are keen to feed low-producing late-lactation cows only once per day (1×) to reduce production costs. This study examined effects of feeding frequency (FF: thrice versus once daily) on behavioral patterns, ruminal fermentation, and milk production performance of cows and supplementation of yellow grease oil (YO) rich in 18:2n-6 as a potential strategy to alleviate the possible negative effects of 1× daily feeding. Twenty-four late-lactation Holstein cows (215 ± 53.8 DIM) housed in tiestalls were assigned to 4 treatments according to a 2 × 2 factorial arrangement with 2 FF [3 times daily (3×) at 0800, 1400, and 2000 h; or 1× at 0800 h] and 2 high-forage total mixed rations (TMR), without (CON) or with 25 g/kg of dry matter of YO (YGO), in a randomized complete block design. Treatments were applied for 21 d. Feeding behavior was recorded every 5 min over a 24-h period on d 19. Fresh TMR and orts were sampled (d 15 to 21) and separated using a 3-screen (19, 8, and 1.18 mm) Penn State Particle Separator for sorting activity. Ruminal fluid samples were collected using oral stomach tubing on d 21. Cows on 1×-CON spent more time eating during the first 6 h after feeding at 0800 h than did cows on 3×-CON or 1×-YGO. Decreasing FF increased meal length and tended to increase meal size for CON cows, but supplementing YO increased meal bouts and reduced meal length and size for cows fed 1×. Cows on 1×-CON had the greatest ruminating time between 2000 and 0800 h compared with other treatments. Total and daytime distribution of lying time did not vary by treatments. Sorting activity was higher for cows fed frequently, and the extent of sorting was increased by oil supplementation. In the morning ruminal fluid samples, pH was not different among treatments, but in the evening samples 1× daily feeding reduced ruminal pH compared with 3×. In the morning and evening samples, ratios of acetate to propionate were the lowest for 1×-CON cows compared with other treatments. Dry matter intake and milk yield were similar among the groups. Milk fat content and yield decreased with 1×-CON treatment, but supplementing YO numerically increased milk fat for cows fed 1×. These results suggest that decreasing FF from 3× to 1× daily increases meal length, particularly after feed delivery, in cows fed high-forage diets; but supplementation of plant oil changes feeding patterns and may improve ruminal pH and milk fat in cows fed once a day.

The objectives of this study were to investigate the effect of a maximum recommended oil supplementation on growth performance, eating behavior, ruminal fermentation, and ruminal morphological characteristics in growing lambs during transition from a low- to a high-grain diet. A total of 21 Afshari male lambs with an initial body weight (BW) of 41.4 ± 9.1 kg (mean ± SD) and at 5–6 months of age were randomly assigned to one of three dietary treatments (n = 7 per group), including (1) a grain-based diet with no fat supplement (CON), (2) CON plus 80 g/d of prilled palm oil (PALM), and (3) CON plus 80 g/d soybean oil (SOY); oils were equivalent to 50 g/kg of dry matter based on initial dry matter intake (DMI). All lambs were adapted to the high-grain diet for 21 d. In the adaptation period, lambs were gradually transferred to a dietary forage-to-concentrate ratio of 20:80 by replacing 100 g/kg of the preceding diet every 3 d. Thereafter, lambs were fed experimental diets for another 22 days. Fat-supplemented lambs had greater DMI, body weight (BW), and average daily gain (ADG), with a lower feed to gain ratio (p < 0.05), compared to CON lambs. The highest differences of DMI between fat-supplemented and CON-lambs were observed in week 3 of the adaptation period (p = 0.010). PALM- or SOY-supplementation lowered DM and NDF digestibility compared with CON (p < 0.05), and SOY caused the lowest organic matter (OM) digestibility compared with CON and PALM lambs (62.0 vs. 67.6 and 66.9; p < 0.05). Ruminal pH was higher for PALM and SOY compared with CON (p = 0.018). Lambs in SOY tended to have the highest ammonia-N concentrations (p = 0.075), together with a trend for higher concentrations of propionic acid, at the expense of acetic acid in ruminal fluid, on the last day of the adaptation period (diet × time, p = 0.079). Fat-supplemented lambs had lower isovaleric and valeric acid concentrations compared with CON on d 40 (diet × time, p < 0.05). PALM and SOY-fed lambs had a longer eating time (min/d and min/kg of DMI), chewing activity (min/d), meal frequency (n), and duration of eating the first and second meals after morning feeding (p < 0.05), and the largest meal size (p < 0.001). Fat supplemented lambs had greater ruminal papillary length (p < 0.05) and width (p < 0.01), and thicker submucosal, epithelial, and muscle layers, compared with the CON (p < 0.01). Blood metabolites were not influenced by dietary treatments (p > 0.05). The results from this study suggest that fat supplementation to high-grain diets may improve the development of ruminal epithelia and modify ruminal fermentation via optimized eating behavior or the direct effect of oils on the ruminal environment, resulting in better growth performance in growing lambs.

The feeding of high-concentrate diets commonly results in lowered pH and ruminal dysbiosis which cause shifts in uptake dynamics of short-chain fatty acids (SCFA) and altered epithelial function. Therefore, the current study evaluated the effect of dietary polyunsaturated fatty acids (PUFA) on ruminal fermentation products, gene expression in the ruminal epithelium and the associated changes in ruminal microorganisms in lambs fed a high-concentrate diet. Twenty-six Afshari lambs adapted to a high-concentrate diet during a completely randomised design were fed with a basal diet supplemented with 100 g oil supplement (OS; 60 g sunflower oil and 40 g fish oil) for 10 (OS10), 20 (OS20) and 30 (OS30) d, respectively (n = 6). Lambs with no oil supplementation (OS0, n = 8) were considered as control and slaughtered at d 0 of the experiment, and the remaining lambs were slaughtered at 10, 20 and 30 d on feed. After slaughter, ruminal digesta was collected for evaluating fermentation and microbial community. Ruminal papillae were taken for assessment of epithelial gene expression. Compared with OS0 lambs, supplemental PUFA in OS30 lambs tended to decrease total SCFA concentration with decreased acetic and increased propionic acid concentrations. Acetate:propionate ratios were decreased and ruminal pH was increased in OS20 and OS30 lambs compared to OS0. All groups with included OS had decreased concentrations of iso-valeric and valeric acids compared to OS0. Relative mRNA abundance of monocarboxylate transporter isoforms 1 and 4, insulin-like growth factor binding protein 3, sterol regulatory element-binding proteins 1 and 2 decreased with increasing OS duration. The relative abundance of 3-hydroxy-3-methylglutaryl-CoA synthase 1 mRNA transcript was higher for OS10 and OS20 lambs relative to OS0 lambs. OS20 and OS30 showed a decrease of lipopolysaccharide binding protein mRNA expression compared with OS0. Feeding supplemental PUFA decreased Ciliate protozoa and increased Butyrivibrio fibrisolvens in OS20 and OS30 lambs, whereas Megasphaera elsdenii was increased in OS30 lambs. In conclusion, combined supplementation of sunflower and fish oil to a high-concentrate diet affects the ruminal microbial community with prominent decreases in ruminal ciliate protozoa and increases in B. fibrisolvens and M. elsdenii. These results lead to a more stabilised ruminal pH and a fermentation shift towards more propionate generation. Consideration of nutrients digestion will help to fully understand the benefits of feeding PUFA with a high-concentrate diet.