Corn Silage Diet Research Articles

Does sugar cane ensiled with calcium oxide affect intake, digestibility, performance, and microbial efficiency in beef cattle?

Two trials were conducted to evaluate how calcium oxide (CaO) as an additive in sugar cane silage affects animal performance and diet digestibility. Experiment 1 included 35 crossbred steers (Holstein×Nellore) with an average body weight (BW) of 350±18.3kg, which were distributed across a randomized block design with five treatments and seven replicates. The five treatments consisted of sugar cane ensiled with four different levels of CaO (0, 5, 10, and 15g/kg; fresh basis) and a standard diet of corn silage. The forage concentrate ratio was 50:50 and was formulated to be isonitrogenous (120g/kg DM). The dry matter intake (DMI) was measured daily and individually. Indigestible acid detergent fiber (iADF) was used as an internal marker to estimate apparent nutrient digestibility. There was a quadratic positive effect (P=0.013) of the CaO levels on DMI (gDM/kgBW), organic matter (OM; P=0.032), and non-fiber carbohydrates (NFC; P=0.014) intake. The average daily gain (ADG) of steers that were fed corn silage diets was similar (P=0.11) to that of those fed sugar cane silage with 5g/kg of CaO. There was a positive linear effect of the percentage of CaO on the apparent total digestibility of DM (P=0.012), OM (P=0.001), crude protein (CP; P=0.022) and neutral detergent fiber (aNDF; P=0.015) of the diets. In Experiment 2, four ruminally and abomasally cannulated Nellore steers (184±10.2kgBW) were used with a 4×4 Latin square design to evaluate the effect of CaO levels on apparent total and ruminal digestibility of nutrients, ruminal characteristics, and microbial efficiency. The four treatments were composed of the same sugar cane silage diets used in Experiment 1. The aNDF intake decreased linearly (P=0.032) as the percentage of CaO increased. There was a linear positive effect of the percentage of CaO on the apparent total digestibility of DM (P=0.036), OM (P=0.007), CP (P=0.042), and aNDF (P=0.025). There were no effects of CaO levels on the ruminal pH values (P=0.52), ammonia concentration (P=0.22), or microbial efficiency (P=0.283). Adding CaO to sugar cane silage reduces the silage fiber. However, the addition of more than 5g/kg CaO to sugar cane at ensiling does not improve silage intake and animal performance. Additionally, the use of 15g/kg of CaO in sugar cane at ensiling decreases diet intake and growth of beef cattle.

Elephant grass ensiled with wheat bran compared with corn silage in diets for lactating goats

The objective of this study was to evaluate the use of wheat bran as an additive in elephant-grass silage on intake and digestibility of the nutrients, ingestive behavior, and yield and chemical composition of milk. Eight goats with 45 days of lactation were distributed in a (4 × 4) Latin square design.The treatments consisted of corn silage (CS), elephant-grass silage without wheat bran (EGS), elephant-grass silage with 10% wheat bran (EGS+10%WB), and elephant-grass silage with 20% wheat bran (EGS+20% WB). There was no difference in dry matter (DM) intake between diets EGS and CS in g d−1. However, the animals fed EGS+10%WB had lower DM and organic matter (OM) intakes than the animals fed CS in g kg−1 d−1 of body weight. There were lower non-fiber carbohydrate and metabolize energy intakes by animals fed diets based on elephant-grass silages than those fed CS. The EGS+20%WB diet provided lower digestibility coefficients of DM, OM, crude protein, ether extract, neutral detergent fiber (NDF) and digestible nutrients of the diet than the diet with CS. The NDF digestibility coefficient with diet EGS was greater than that obtained with diet CS. The diets with corn and elephant-grass silages provided similar milk yield levels. However, the animals fed diets based on EGS+20% WB produced less total-solids-corrected milk than the animals fed CS. No difference was found in the milk physicochemical properties and ingestive behavior of goats in this study. Corn silage can be replaced by elephant-grass silage harvested at 50 days of regrowth and elephant-grass silage with 10% wheat bran without influencing goat performance, behavioral variables, physiological variables, milk yield or the milk physicochemical properties.

Exchanging physically effective neutral detergent fiber does not affect chewing activity and performance of late-lactation dairy cows fed corn and sugarcane silages

The objective of this study was to determine whether replacing the physically effective neutral detergent fiber (peNDF) of corn silage with sugarcane silage peNDF would affect performance in dairy cows. Twenty-four late-lactation Holstein cows were assigned to eight 3×3 Latin squares with 21-d periods. The dietary treatments were (1) 25% peNDF of corn silage, (2) 25% peNDF of sugarcane silage, and (3) 12.5% peNDF of corn silage + 12.5% peNDF of sugarcane silage. The physical effectiveness factors (pef) were assumed to be 1 for corn silage and 1.2 for sugarcane silage, as measured previously by bioassay. Thus, peNDF was calculated as neutral detergent fiber (NDF) × pef. The concentrate ingredients were finely ground corn, soybean meal, pelleted citrus pulp, and mineral-vitamin premix. Dry matter intake (22.5±0.63kg/d), 3.5% fat-corrected milk yield (28.8±1.13kg/d), milk composition (fat, protein, lactose, urea, casein, free fatty acids, and somatic cell count), and blood metabolites (glucose, insulin, and nonesterified fatty acids) were unaffected by the treatments. The time spent eating, ruminating, or chewing was also similar among the diets, as was particle-sorting behavior. By contrast, chewing per kilogram of forage NDF intake was higher for the sugarcane silage (137min/kg) than the corn silage diet (116min/kg), indicating the greater physical effectiveness of sugarcane fiber. Based on chewing behavior (min/d), the estimated pef of sugarcane silage NDF were 1.28 in the corn silage plus sugarcane silage diet and 1.29 in the sugarcane silage diet. Formulating dairy rations of equal peNDF content allows similar performance if corn and sugarcane silages are exchanged.

Replacing corn silage with different forage millet silage cultivars: Effects on milk yield, nutrient digestion, and ruminal fermentation of lactating dairy cows

This study investigated the effects of dietary replacement of corn silage (CS) with 2 cultivars of forage millet silages [i.e., regular millet (RM) and sweet millet (SM)] on milk production, apparent total-tract digestibility, and ruminal fermentation characteristics of dairy cows. Fifteen lactating Holstein cows were used in a replicated 3×3 Latin square experiment and fed (ad libitum) a high-forage total mixed ration (68:32 forage:concentrate ratio). Dietary treatments included CS (control), RM, and SM diets. Experimental silages constituted 37% of each diet DM. Three ruminally fistulated cows were used to determine the effect of dietary treatments on ruminal fermentation and total-tract nutrient utilization. Relative to CS, RM and SM silages contained 36% more crude protein, 66% more neutral detergent fiber (NDF), and 88% more acid detergent fiber. Cows fed CS consumed more dry matter (DM; 24.4 vs. 22.7kg/d) and starch (5.7 vs. 3.7kg/d), but less NDF (7.9 vs. 8.7kg/d) than cows fed RM or SM. However, DM, starch and NDF intakes were not different between forage millet silage types. Feeding RM relative to CS reduced milk yield (32.7 vs. 35.2kg/d), energy-corrected milk (35.8 vs. 38.0kg/d) and SCM (32.7 vs. 35.3kg/d). However, cows fed SM had similar milk, energy-corrected milk, and solids-corrected milk yields than cows fed CS or RM. Milk efficiency was not affected by dietary treatments. Milk protein concentration was greatest for cows fed CS, intermediate for cows fed SM, and lowest for cows fed RM. Milk concentration of solids-not-fat was lesser, whereas milk urea nitrogen was greater for cows fed RM than for those fed CS. However, millet silage type had no effect on milk solids-not-fat and milk urea nitrogen levels. Concentrations of milk fat, lactose and total solids were not affected by silage type. Ruminal pH and ruminal NH3-N were greater for cows fed RM and SM than for cows fed CS. Total-tract digestibility of DM (average=67.9%), NDF (average=53.9%), crude protein (average=63.3%), and gross energy (average=67.9%) were not influenced by dietary treatments. It was concluded that cows fed CS performed better than those fed RM or SM likely due to the higher starch and lower NDF intakes. However, no major differences were noted between the 2 forage millet silage cultivars.

<b>Feedlot performance of bulls and steers fed on three levels of concentrate in the diets

Current study evaluated the effect of different sexual groups and different concentrate levels in diets on animal performance, feed efficiency and carcass characteristics of bovines finished in feedlot. Ninety four bulls and 75 steers Purunã with average age 19 months at the beginning of the feedlot period were used. Animals were maintained in individual pens during 116 days and fed with a diet of corn silage and three concentrate levels (0.8, 1.1, and 1.4% of body weight). The concentrate was formulated with 25% soybean meal, 73% corn grain, 1.0% of a mineral mix and 1.0% limestone and adjusted at every 28 days. The interaction between sexual groups and concentrate levels was not significant for any of the studied variables. Bulls were more efficient than steers ones, with higher average daily gain (1.33 vs. 1.12 kg day-1), better feed conversion ratio (6.6 vs. 7.6 kg DM intake kg-1 gain), and higher carcass gain (86.6 vs. 69.2 kg). Increase in concentrate level in diet did not influence animal performance even though a higher DM was observed for animals fed on 1.4% (8.8 kg) and 1.1% (8.4 kg) levels of concentrate when compared with those fed on 0.8% level (7.7 kg).

Protein supplementation for growing cattle fed a corn silage–based diet

<h2>ABSTRACT</h2> The objectives were to determine effects of protein supplementation in corn silage–based diets on growing cattle performance and economics of gain. In Exp. 1, steers (n=144; initial BW=269±60kg) were blocked by BW. The 6 pens within each block were randomly assigned to 1 of 3 protein supplements: 1) urea, 2) soybean meal, or 3) dried distillers grains with solubles (DDGS). The diets contained 79% corn silage and 21% CP, vitamin, and mineral supplement (DM basis). Protein supplements were formulated to achieve 11.5% total dietary protein (DM basis) and were fed for 84 d. In Exp. 2, steers (n=34, initial BW=198±28kg) and heifers (n=19, initial BW=194±42kg) were blocked by sex and allotted to 9 pens (3 pens of heifers and 6 pens of steers). Pens within block were randomly assigned to 1 of 3 protein supplements: 1) 11% CP, 2) 12% CP, or 3) 13% CP. Urea was used to increase protein concentrations by treatment, and diets contained 90% corn silage and 10% corn-based supplement containing urea, vitamins, and minerals (DM basis). In Exp. 1, cattle fed DDGS and soybean meal had greater (P<0.01) ADG, DMI, G:F, and final BW than those fed urea-based protein supplements with corn-silage diets. Ingredient price differences resulted in cattle fed DDGS having the least (P<0.01) cost per kilograms of BW gain. In Exp. 2, increasing dietary urea concentration tended to linearly decrease (P=0.08) ADG and G:F. Cattle fed 11 or 12% CP had the least cost per kilograms of BW gain. Cattle fed soybean meal or DDGS with corn silage had comparable growth performance, and using DDGS as a protein supplement to corn silage–based diets provided the most economical return.

Características da carcaça e da carne de bovinos não-castrados ou castrados terminados em confinamento e alimentados com três níveis de concentrado

The objective of this experiment was to evaluate quantitative and qualitative characters of carcass and meat from bulls and steers finished in feedlot during a 116 day period, in individual stalls and fed with a diet of corn silage and three levels of concentrate (0.70; 0.97 and 1.23% of body weight). The concentrate was formulated with 25% soybean meal, 73% of ground corn grain 1% of a mineral mix and 1% of limestone. A total of 169 composite Puruna animals, being 94 bulls and 75 steers with average age of 20 months. The interaction between physiological condition and level of concentrate was not significant (P>0.05) for any of the studied variables. Likewise, no effect of level of concentrate was detected upon the same traits. The bulls presented heavier slaughter weight (493.1 kg) in comparison with the steers (450.0 kg) as well as higher carcass yield (55.2 vs. 53.5%), resulting in a hot carcass weight 12.1% heavier than bulls animals, though with a lower degree of carcass finishing (3.6 vs. 4.2 mm, respectively). Bulls produced carcasses with better conformation and higher area of Longissimus dorsi (68.6 vs. 63.3 cm2), and higher percentage of muscle in comparison with castrated (66.5 vs. 62.8%). The meat from bulls was darker and with lower degree of marbling in relation to steers. Nevertheless, no differences were observed for tenderness nor for juiciness, though steers had more palatable meat.

Methane production, digestion, ruminal fermentation, nitrogen balance, and milk production of cows fed corn silage- or barley silage-based diets

This study evaluated the effects of replacing barley silage (BS) with corn silage (CS) in dairy cow diets on enteric CH4 emissions, ruminal fermentation characteristics, digestion, milk production, and N balance. Nine ruminally cannulated lactating cows were used in a replicated 3×3 Latin square design (32-d period) and fed (ad libitum) a total mixed ration (TMR; forage:concentrate ratio 60:40; dry matter basis) with the forage portion consisting of either barley silage (0% CS; 0% CS and 54.4% BS in the TMR), a 50:50 mixture of both silages (27% CS; 27.2% CS and 27.2% BS in the TMR), or corn silage (54% CS; 0% BS and 54.4% CS in the TMR). Increasing the CS proportion (i.e., at the expense of BS) also involved increasing the proportion of corn grain (at the expense of barley grain). Intake and digestibility of dry matter and milk production increased linearly as the proportion of CS increased in the diet. Increasing dietary CS proportion decreased linearly the acetate molar proportion and increased linearly that of propionate. Daily CH4 emissions tended to respond quadratically to increasing proportions of CS in the diet (487, 540, and 523 g/d for 0, 27, and 54% CS, respectively). Methane production adjusted for dry matter or gross energy intake declined as the amount of CS increased in the diet; this effect was more pronounced when cows were fed the 54% CS diet than the 27% CS diet. Increasing the CS proportion in the diet improved N utilization, as reflected by decreases in ruminal ammonia concentration and urinary N excretion and higher use of dietary N for milk protein secretion. Total replacement of BS with CS in dairy cow diets offers a strategy to decrease CH4 energy losses and control N losses without negatively affecting milk performance.

Effect of dietary inclusion of whole ear corn silage on stomach development and gastric mucosa integrity of heavy pigs at slaughter

The effect of dietary inclusion of whole ear corn silage on stomach development and on the incidence of gastric lesions was studied in heavy pigs. Three groups of 14 castrated male pigs were fed a control cereal-based diet and two diets containing whole ear corn silage (15% or 30% DM) from 90kg bodyweight to slaughter at 170kg. The diets with whole ear corn silage increased the amount of neutral detergent fibre in the stomach contents, the weight of the organs and the area of the pyloric region. Follicular gastritis was significantly lower and gastritis less severe in pigs fed the whole ear corn silage diets than pigs fed the control diet. The inclusion of whole ear corn silage in the diet influenced the development of the stomach and reduced the incidence of gastritis in heavy pigs.

Effects of feeding corn modified wet distillers grain plus solubles co-ensiled with chopped whole plant corn on heifer growth performance and diet digestibility in beef cattle1

Two experiments were conducted to evaluate the effect of feeding corn modified wet distillers grain plus solubles (MWDGS; 48% DM) co-ensiled with chopped whole plant corn (WC) on growth performance, dietary intake, and nutrient digestibility of beef cattle. In Exp. 1, 96 Angus-crossed heifers (2 yr old; 522 ± 49.1 kg BW; 5.3 ± 0.1 BCS) were stratified and blocked according to BW and stratified by BCS in each block in a randomized complete block design (24 pens; 4 heifers/pen; 6 treatment replications). Groups were assigned to 1 of 4 dietary treatments for a 62 d trial. Treatments were 1) corn silage (CS) and soybean meal (CON), 2) MWDGS co-ensiled with chopped whole plant corn (WC; CO-EN), 3) CS mixed with MWDGS at feeding (CS+WDG), and 4) CS mixed with dry distillers grain plus solubles (DDGS) at feeding (CS+DDG). In Exp. 2, 4 crossbred beef steers (initial BW = 278 ± 18 kg) fitted with permanent ruminal cannulas were used in a balanced 4 × 4 Latin square to test the effects of feeding MWDGS co-ensiled with WC on DM intake, ruminal fermentation characteristics, and total tract digestibility. There were four 14-d periods, with 10 d for diet adaptation and 4 d for samples collection. Orthogonal contrasts were used and compared CON vs. diets containing distillers grains (DGD), CO-EN vs. diets where distillers grains were mixed at feeding (MIX), and CS+WDG vs. CS+DDG. In Exp. 1, the CON fed heifers resulted in greater G:F (P = 0.04) compared with those fed DGD. However, ADG (P = 0.03), final BW (P = 0.04), and BW gain (P = 0.03) were greatest for DGD diets compared with CON and greatest (P = 0.04) for CO-EN when compared with MIX. Apart from a slightly greater acetate concentration (P = 0.05), which resulted in a greater acetate to propionate ratio (P = 0.03) for the CON diet compared with DGD, no important differences were observed on intake, diet digestibility, or fermentation characteristics when comparing the CON treatment with DGD or when comparing CS+WDG with CS+DDG. However, the CO-EN diet resulted in decreased DMI (P = 0.05) and consequently decreased OM (P = 0.05), N (P = 0.04), and NDF (P = 0.02) intakes compared with MIX. Data from these studies suggest that MWDGS co-ensiled with WC can successfully replace traditional corn-based diets supplemented with soybean meal and corn silage diets supplemented with distillers grains without compromising digestibility and growth performance in pregnant heifers.

Corn silage in dairy cow diets to reduce ruminal methanogenesis: Effects on the rumen metabolically active microbial communities

Methane produced by the methanogenic Archaea that inhabit the rumen is a potent greenhouse gas and represents an energy loss for the animal. Although several strategies have been proposed to mitigate enteric CH4 production, little is known about the effects of dietary changes on the microbial consortia involved in ruminal methanogenesis. Thus, the current study aimed to examine how the metabolically active microbes are affected when dairy cows were fed diets with increasing proportions of corn silage (CS). For this purpose, 9 ruminally cannulated lactating dairy cows were used in a replicated 3 × 3 Latin square design and fed a total mixed ration (60:40 forage:concentrate ratio on a dry matter basis) with the forage portion being either alfalfa silage (0% CS), corn silage (100% CS), or a 50:50 mixture (50% CS). Enteric CH4 production was determined using respiration chambers and total rumen content was sampled for the determination of fermentation characteristics and molecular biology analyses (cDNA-based length heterogeneity PCR, quantitative PCR). The cDNA-based length heterogeneity PCR targeting active microbes revealed similar bacterial communities in cows fed 0% CS and 50% CS diets, whereas important differences were observed between 0% CS and 100% CS diets, including a reduction in the bacterial richness and diversity in cows fed 100% CS diet. As revealed by quantitative PCR, feeding the 100% CS diet increased the number of total bacteria, Prevotella spp., Archaea, and methanogenic activity, though it reduced protozoal number. Meanwhile, increasing the CS proportion in the diet increased propionate concentration but decreased ruminal pH, CH4 production (L/kg of dry matter intake), and concentrations of acetate and butyrate. Based on these microbial and fermentation changes, and because CH4 production was reduced by feeding 100% CS diet, this study shows that the use of cDNA-based quantitative PCR to estimate archaeal growth and activity is not reliable enough to reflect changes in ruminal methanogenesis. A more robust technique to characterize changes in archaeal community structures will help to better understand the microbial process involved in ruminal methanogenesis and, hence, enabling the development of more effective dietary CH4 mitigation strategies.

Replacing alfalfa silage with corn silage in dairy cow diets: Effects on enteric methane production, ruminal fermentation, digestion, N balance, and milk production

The objective of this study was to determine the effects of replacing alfalfa silage (AS) with corn silage (CS) in dairy cow total mixed rations (TMR) on enteric CH4 emissions, ruminal fermentation characteristics, apparent total-tract digestibility, N balance, and milk production. Nine ruminally cannulated lactating cows were used in a replicated 3×3 Latin square design (32-d period) and fed (ad libitum) a TMR [forage:concentrate ratio of 60:40; dry matter (DM) basis], with the forage portion consisting of either alfalfa silage (0% CS; 56.4% AS in the TMR), a 50:50 mixture of both silages (50% CS; 28.2% AS and 28.2% CS in the TMR), or corn silage (100% CS; 56.4% CS in the TMR). Increasing the CS proportion (i.e., at the expense of AS) in the diet was achieved by decreasing the corn grain proportion and increasing that of soybean meal. Intake of DM and milk yield increased quadratically, whereas DM digestibility increased linearly as the proportion of CS increased in the diet. Increasing the dietary CS proportion resulted in changes (i.e., lower ruminal pH and acetate:propionate ratio, reduced fiber digestibility, decreased protozoa numbers, and lower milk fat and higher milk protein contents) typical of those observed when cows are fed high-starch diets. A quadratic response in daily CH4 emissions was observed in response to increasing the proportion of CS in the diet (440, 483, and 434 g/d for 0% CS, 50% CS, and 100% CS, respectively). Methane production adjusted for intake of DM, and gross or digestible energy was unaffected in cows fed the 50% CS diet, but decreased in cows fed the 100% CS diet (i.e., quadratic effect). Increasing the CS proportion in the diet at the expense of AS improved N utilization, as reflected by the decreases in ruminal NH3 concentration and manure N excretion, suggesting low potential NH3 and N2O emissions. Results from this study, suggest that total replacement of AS with CS in dairy cow diets offers a means of decreasing CH4 output and N losses. However, the reduction in fiber degradation and the resulting increase in volatile solids content of the manure may lead to increased CH4 emissions from manure storage.

Short communication: Effects of level of rumen-degradable protein and corn distillers grains in corn silage-based diets on milk production and ruminal fermentation in lactating dairy cows

Two of the potential obstacles precluding inclusion of higher levels of dry distillers grains with solubles (DDGS) in corn-based dairy cow diets are the low levels of rumen-degradable protein (RDP) and the fatty acid content and composition of DDGS. Therefore, the objective of this experiment was to evaluate the production and rumen responses to dietary alterations in the level of RDP and DDGS for dairy cows fed a high corn silage diet. The experimental design was a replicated 4×4 Latin square with 21-d periods: 14 d of adaptation and 7 d of sampling; 16 uncannulated cows and 4 ruminally cannulated cows were blocked and assigned randomly to treatment sequences. Rations were provided as total mixed rations and were formulated to be high or low in RDP, with or without DDGS replacing soybean-based concentrates: high RDP, no DDGS (HRDP0); low RDP, no DDGS (LRDP0); low RDP, 10% DDGS; and low RDP, 20% DDGS. Body weight (696kg) and dry matter intake (26.6 kg/d) were not affected by treatment. Rumen ammonia concentration was greater for HRDP0 than LRDP0, but was unaffected by level of DDGS inclusion. The mean and minimum rumen pH and time pH was <5.5 were not different between diets. Milk production tended to be lower for cows fed HRDP0 than LRDP0 and tended to be linearly reduced as DDGS inclusion increased. Milk protein yield tended to be greater for cows fed LRDP0 than HRDP0, but was unaffected by DDGS level. Milk fat production, concentration, and fat-corrected milk were linearly reduced by increasing levels of DDGS. Based on these results, feeding DDGS at 20% of diet dry matter is not recommended for diets based on high corn silage.

Betacarotene supplementation increases ovulation rate without an increment in LH secretion in cyclic goats

This study aimed to evaluate the effects of betacarotene (BC) supplementation on ovulation rate (OR) and luteinizing hormone (LH) secretion in adult goats during the breeding season. Additionally, total ovarian activity (TOA) comprising the total number of ultrasonographically detectable antral follicles (AF) and corpora lutea (OR) was also assessed. In early October, adult goats [n=22, 3.5 years of age, 7/8 Sannen-Alpine; 26°N, 103°W at 1117m.a.s.l.] were randomly assigned to: (i) BC group (BCG), orally supplemented with 50mg of BC/goat/day [n=10; live weight (LW)=45.9±2.0kg, body condition score (BCS; range: 0-emaciated to 5-obese)=3.0±0.1], and (ii) control group (CONT) [n=12; LW=46.2±2.0kg, BCS=3.0±0.1]. All animals received a basal diet of alfalfa hay, corn silage and corn grain, with free access to water and mineral salts. The whole experimental period spanned 34 days before and 17 days after ovulation. On day 23 of the experiment, estrus was synchronized with progestin-releasing intravaginal sponges; 36h prior to estrus, an intensive blood sampling (every 15min for 6h) was performed to determine mean LH concentrations, pulsatility (LH-PULSE) and area under the curve (LH-AUC) for serial LH concentrations. Afterwards, by the end of the luteal phase (i.e., 17 days after the onset of estrus), an ultrasonographic scanning was performed to evaluate OR and TOA [AF+OR]. The average LW and BCS did not differ (p>0.05) during the experimental period. BC-supplemented goats showed an increase in OR (3.4±0.2 versus 2.8±0.2; p<0.05) and exhibited lower (p<0.05) serum LH concentrations, LH-AUC and LH-PULSE compared to CONT. A positive correlation was recorded between OR and LW (r2=0.42, p<0.05) and BCS (r2=0.47, p<0.05). In addition, AF (5.0±0.6 versus 3.4±0.6) and TOA (8.4±0.6 versus 6.2±0.6) were greater (p<0.05) in the BC-supplemented group than CONT. Supplementation with BC enhanced ovarian follicular development and ovulation rate in adult female goats under decreased photoperiods through LHRH-independant pathways or direct effects of BC on ovarian function.

English

To determine the effects of two corn silage particle size (coarse particle with geometric mean of 5.83 ± 2.47 mm and fine particle with geometric mean of 4.74 ± 2.74 mm) and two levels of soybean oil (0 and 4% of DM) on ruminal matcomposition, distribution and consistency, four two years fistulated ruminant Zel ewes (BW = 34 ± 1.4 kg), fed with 50:50 roughage-concentrate diet, were allocated to a 4 × 4 change over design. The experiment was carried out in 4 periods of 28-days trial (adaptation, 14 days; collection period‎, 5 days; chewing activity measurement, 1 day; rumen evacuation, 8 days). Experimental diets were: 1) basal diet + coarse corn silage and 0% oil; 2) basal diet + coarse corn silage and 4% oil; 3) basal diet + fine corn silage and 0% oil and; 4) basal diet + fine corn silage and 4% oil. Based on calendar time, rumens were evacuated manually at 3, 7.5 and 12 h post-feeding of each period and total ruminal contents were separated into mat and liquids phase. Dry matter (DM) and organic matter (OM) intake were less in treatment 4 and neutral detergent fiber (NDF) intake in treatment 2 was higher than in the other diets. Physically, effective NDF intakes were higher in treatments 1 and 2 than in treatments 3 and 4, but DM and OM digestibility was higher in treatments 1 than in the other diets. The NDF digestibility was higher in coarse silage diets, but the NFC digestibilities were higher in fine corn silage diets. Rumen mat was greater in coarse silage diets than in fine silage diets (1.83 and 1.32 versus 1.06 and 0.76 kg) at 3 h after feeding. Non-escapable pool sizes in rumen content were higher in diets that contained coarse silage. At all time in post feeding, ruminal pH was less in fine silage particle size with oil supplement. Rumen particulate passage rates were higher in fine corn silage diets. However, passage rates from the lower gastrointestinal tract were similar. In addition, ruminal mean retention times were significantly greater in diets that contained coarse silage. Rumination time was shorter in fine corn silage with oil supplement diet but rumination time per kg of NDF and peNDF was longer in fine corn silage diets. In addition, although reduction of particle size decreased size of rumen mat and non-escapable fraction, oil supplementation reduced ruminal digestion and mean retention of ruminal particulate. However, it seems that oil supplementation can be helpful in fine corn silage diets for maintaining ruminal mat. Key words: Particle size, soybean oil, ruminal mat, Zel sheep

Short-term beta-carotene-supplementation positively affects ovarian activity and serum insulin concentrations in a goat model.

In early October 2010, adult goats (no.=22, 3.5 yr old, 7/8 Sannen-Alpine, 26° N, 103° W, at 1117 m), were randomly assigned to: i) beta-carotene group (BC) [no.=10; live weight (LW)=45.9±1.97 kg, body condition score (BCS) =3.04±0.08; orally supplemented with 50 mg of BC per goat per day]; ii) control group (CONT) (no.=12; LW=46.2±2.04 kg, BCS=3.0±0.08). Animals received a basal diet of alfalfa hay, corn silage, and corn grain, having free access to water, shade, and mineral salts. During the second half of October, estrus was synchronized by using intravaginal sponges. Thereafter, by mid-follicular phase, an intensive blood sampling (6 h × 60 min) was performed to evaluate serum insulin concentrations (INS) by radioimmunoassay. By the end of the luteal phase, an ultrasonographic scanning was performed to evaluate total ovarian activity (TOA) [TOA=total follicles (TF) + total corpus luteum (TCL)]. The whole experimental period consisted of 34 days pre- and 17 days post-ovulation, for a total of 52 days. Average LW and BCS did not differ (p>0.05) during the experimental period. Nonetheless, increases in TF no. (5.0 vs 3.4±0.6 units; p=0.05), TCL no. (3.4 vs 2.8±0.2 units; p=0.05), TOA (8.1 vs 6.2±0.6 units; p=0.05) and INS (4.6 vs 3.9±0.4 ng ml-1; p=0.05) favored to the BC-supplemented group. A positive correlation between LW (r(2)=0.42; p=0.04) and BCS (r(2)=0.47; p=0.02) with respect to ovulation rate, was detected. BC-supplementation increased ovarian activity in the female goat while positively affected the release pattern of insulin, suggesting a potential role of BC as a central and/or pancreas-activating molecule in adult goats; such results may hold not only physiologic but also clinical significance.

Use of manure concentrations of ash or specific minerals and nitrogen to estimate loss of volatile nitrogen from manure incubated under laboratory conditions

Changes in the ratio of volatile N to non-volatile specific minerals or total ash in manure can potentially be used to estimate losses of N from manure. The aim of this study was to evaluate the accuracy of using specific minerals (P, K, Ca, Mg, and Na) or total ash as markers to estimate volatile N losses from incubated manure slurries. Holstein cows were fed diets with the forage as predominantly corn silage (CS) or alfalfa silage (AS) or a diet identical to the CS diet except 5g/kg urea was added (CSU). Total output of urine and feces were measured and used to prepare two types of slurry mixtures (all slurry mixtures contained 1200g of manure per tray): (1) as excreted (AsEx) and (2) AsEx+sand (SAND). The SAND slurry was designed to mimic manure from barns that used sand as a bedding material. Feces and urine were mixed in the same proportion as excreted by the cows for both slurry types and 240g of sand were added to the SAND slurries. Initial and final (3d incubation period) slurry weights and concentrations of N, ash, and specific minerals were measured to calculate loss of volatile N. Losses of volatile N from the slurries were estimated as: (N intake−N milk)−[N/ash×(ash intake−ash milk)], where N and ash intake=g/d consumed by the cow; N and ash milk=g/d secreted in milk; and N/ash=ratio of N and ash concentrations in slurry samples at 3d. To evaluate specific minerals as markers, the same equation was used except that Ca, K, Mg, Na or P replaced the ash term. Measured N losses from the AsEx slurries were 0.44, 0.62, and 1.03g/3d for the AS, CS, and CSU treatments and estimated N losses (using N/ash) were 0.29, 0.49, and 1.14g/3d. Estimated losses were less than measured losses for cows with negative N balance and greater than measured losses for cows in positive N balance. For AsEx slurries, the use of N to specific mineral ratios was generally less accurate than using the N/ash ratio. Estimated N losses from SAND slurries were extremely inaccurate for all markers. The use of the N/ash ratio to estimate N volatilization from manure shows promise but markers that are in appreciable concentrations in bedding material will not be accurate.

Corn silage versus corn silage:alfalfa hay mixtures for dairy cows: Effects of dietary potassium, calcium, and cation-anion difference

Corn silage (CS) has replaced alfalfa hay (AH) and haylage as the major forage fed to lactating dairy cows, yet many dairy producers believe that inclusion of small amounts of alfalfa hay or haylage improves feed intake and milk production. Alfalfa contains greater concentrations of K and Ca than corn silage and has an inherently higher dietary cation-anion difference (DCAD). Supplemental dietary buffers such as NaHCO3 and K2CO3 increase DCAD and summaries of studies with these buffers showed improved performance in CS-based diets but not in AH-based diets. We speculated that improvements in performance with AH addition to CS-based diets could be due to differences in mineral and DCAD concentrations between the 2 forages. The objective of this experiment was to test the effects of forage (CS vs. AH) and mineral supplementation on production responses using 45 lactating Holstein cows during the first 20 wk postpartum. Dietary treatments included (1) 50:50 mixture of AH and CS as the forage (AHCS); (2) CS as the sole forage; and (3) CS fortified with mineral supplements (CaCO3 and K2CO3) to match the Ca and K content of the AHCS diet (CS-DCAD). Feed intake and milk production were equivalent or greater for cows fed the CS and CS-DCAD diets compared with those fed the AHCS diet. Fat percentage was greater in cows fed the CS compared with the AHCS diet. Fat-corrected milk (FCM; 3.5%) tended to be greater in cows fed the CS and CS-DCAD diets compared with the AHCS diet. Feed efficiencies measured as FCM/dry matter intake were 1.76, 1.80, and 1.94 for the AHCS, CS, and CS-DCAD diets, respectively. The combined effects of reduced feed intake and increased FCM contributed to increased feed efficiency with the CS-DCAD diet, which contained 1.41% K compared with 1.18% K in the CS diet, and we speculate that this might be the result of added dietary K and DCAD effects on digestive efficiency. These results indicate no advantage to including AH in CS-based diets, but suggest that improving mineral supplementation in CS-based diets may increase feed efficiency.

Short communication: Effects of replacing part of corn silage and alfalfa hay with Leymus chinensis hay on milk production and composition

The objective of this research was to investigate the effects of replacing part of corn silage (CS) and alfalfa hay (AH) with Leymus chinensis hay on milk production and composition. Twenty multiparous Holstein dairy cows were used in a randomized block design for a 14-week period and 2 treatments. Treatments were (dry matter basis): (1) Non-Leymus chinensis hay diet (NLC; 35% CS, 15% AH) and (2) added Leymus chinensis hay diet (ALC; 30% CS, 10% AH, 10% Leymus chinensis hay). Adding Leymus chinensis hay increased neutral detergent fiber content and in vitro digestibility of the diet. Cows receiving the ALC diet had higher dry matter intake, milk yield, milk protein yield, lactose yield, solids-not-fat yield, and milk fat content compared with those fed the NLC diet. Somatic cell counts of cows decreased in the ALC compared with the NLC treatment. Cis-11 18:1 and 18:2 contents in milk increased, whereas trans-9 and cis-9 18:1 fatty acid contents decreased. Trans-9, cis-11 conjugated linoleic acid content was not influenced by adding Leymus chinensis hay to the diet. Leymus chinensis hay can be used to replace part of CS and AH in diets of dairy cows to get higher milk yield and good milk quality.

Effect of long-term corn by-product feeding on beef quality, strip loin fatty acid profiles, and shelf life

The objective of this study was to evaluate the meat quality and shelf life of steaks from steers fed dried distillers grains with solubles (DDGS) or dried corn gluten feed (CGF) compared with soybean meal with corn (SBM) as a protein supplement from weaning to slaughter. Angus cross steers (n = 81; BW = 306 ± 26.1 kg) were randomly assigned to pens (n = 9) and fed a stocker diet of corn silage (75% of DM) with DDGS, CGF, or SBM and ground ear corn. After 84 d of stockering, 12 steers (BW = 397 ± 15.3 kg) were randomly selected from each treatment and finished using the same protein supplement at 25% of DM for 100 d. Carcass data were collected (24 h) and the longissimus lumborum was fabricated into steaks at 48 h postmortem. Steaks were assigned to proximate analysis, Warner-Bratzler shear force (7-, 14-, or 21-d aging), and retail display (1, 3, 6, or 9 d). Protein source did not affect carcass yield, quality, or longissimus lumborum composition (P > 0.05). After 7 d of aging, DDGS and CGF steaks were more tender (P < 0.01) than SBM, but were similar (P = 0.30) after 14 and 21 d of aging. Feeding corn by-products did not influence subjective overall color acceptance (P = 0.17) in this study, but acceptance declined over time (P < 0.01). Subjective redness was similar (P > 0.05) among diets except SBM steaks were more red (P < 0.01) than DDGS after 9 d. On d 3 and 6 of retail display, CGF steaks exhibited more discoloration (P < 0.04) than SBM or DDGS steaks. However, after 9 d DDGS steaks were more discolored (P < 0.01) than CGF or SBM. Objective L* was lighter for CGF (P < 0.04) over 9 d of display, and all treatments became darker (P < 0.01) as time increased. Redness (a*) declined (P < 0.01) over time with SBM steaks maintaining more color in the red spectrum than CGF and DDGS after 6 d of display. Protein source did not affect (P > 0.05) the rate of lipid oxidation. Total SFA concentrations were similar (P > 0.05) among treatments; however, total MUFA were less (P < 0.05) and total PUFA concentrations were greater (P < 0.05) in DDGS steaks compared with SBM or CGF steaks. These data show that DDGS or CGF can be fed as a protein supplement at 25% DM from weaning until slaughter while maintaining meat quality when compared with steers fed soybean meal as a protein supplement.