Mixture Of Corn Silage Research Articles

Ruminal inocula with distinct fermentation profiles differentially affect the in vitro fermentation pattern of a commercial algal blend.

The in vitro rumen batch technique is widely used for screening novel feed sources; however, it remains unclear to what extent the in vitro fermentability of non-conventional feed sources is affected by non-adapted ruminal inocula. Thus, in this study, we evaluated the effects of distinct ruminal inocula on the in vitro fermentation parameters of a sustainable non-conventional feed, a commercially available algal blend composed of microalgae (Chlorella vulgaris and Nannochloropsis oceanica) and seaweeds (Ulva sp. and Gracilaria gracilis). First, four late-lactation Holstein cows were fed four forage-based diets varying only in the proportions of basal forage (100% corn silage, 70% corn silage and 30% haylage, 30% corn silage and 70% haylage, and 100% haylage) in a 4 × 4 Latin square design with the last square omitted. After 3 weeks of adaptation, haylage-based diets resulted in ruminal fermentation parameters distinct from those promoted by corn silage-based diets, as reflected in increased pH, ammonia-N contents, and acetate proportions. Individual ruminal fluids derived from each of the four diets were further used as inocula in in vitro incubations. Here, a 1:1 mixture of corn silage and haylage was supplemented with 0, 5, 10, or 15% algal blend and incubated with each inoculum for 24 h in a 4 × 4 factorial design. Total gas and methane production decreased with inocula from cows fed haylage-based diets and with increasing algal blend supplementation levels. The fermentation pH increased and the ammonia-N contents decreased with inocula from cows fed haylage-based diets; however, these parameters were not affected by algal blend inclusion levels. The interaction between the ruminal inoculum source and the algal blend supplementation level affected the total volatile fatty acids (VFA) and the proportions of most individual VFA. Total VFA production decreased with increasing algal supplementation levels, particularly with inocula from cows fed 30% corn silage and 70% haylage; the acetate, propionate, and valerate proportions were only affected by algal blend levels under incubation with 100% corn silage inocula. Overall, our findings highlight the importance of the ruminal inoculum source when assessing the fermentability of non-conventional feed as well as the potential of the algal blend as a natural modulator of ruminal fermentation.

Green mass to biogas in Ukraine—bioenergy potential of corn and sweet sorghum

In current times, we heavily rely on the use of fossil fuels, which bring negative impacts on climate change; therefore, it is essential to place more focus on all renewable alternatives, especially bioenergy crops. This study is focused on the quantification and evaluation of biogas production from either corn or sweet sorghum, as well as their combination. The field data were obtained from 2013 to 2016 in central Ukraine. The Buswell equation was used for the calculation of the theoretical biogas and methane potential. The results show that corn and sweet sorghum were intercropping and had higher on 8.5–37.8% of green mass, and 9.5–28.7% estimated yield of biogas compared to the single use of these crops. Due to the higher dry matter content, the specific yield of biogas per unit of applied corn silage was higher by 33.7–50.6% compared to sweet sorghum. However, biogas yield was increased by 9.2–13.0% when using a mixture of corn silage and sweet sorghum compared to sweet sorghum alone. Results of biogas and methane yield per unit area show that the highest rates, 10.2 and 5.9 thousand m3/ha, were obtained in the combined growing of hybrids of sweet sorghum Dovista and corn Monica 350. Even though theoretical calculations have some limitations, the gathered results provide essential information on the potential of the examined green mass for biogas potential in Ukraine. Such information are crucial to be known for economic and energy reasons.

Corn silage supplementation for dairy cows grazing annual ryegrass at two pasture allowances

ABSTRACT Corn silage supplementation for dairy cows grazing in temperate annual pastures has rarely been investigated. The aim of this study is to compare two supplementation levels (0 and 4kg dry matter [DM]/day of a 7:1 mixture of corn silage and soybean meal) in dairy cows strip-grazing annual ryegrass (Lolium multiflorum Lam.) at two pasture allowances (PA, low= 25 and high = 40kg DM/d at ground level). The study was carried out according to an incomplete 4 × 3 Latin square design, using 12 cows and three experimental periods of 12 days. The green leaves allowances were only 4.9 and 8.5kg DM/d at the low and high PA, respectively. The total DM intake and milk production increased in supplemented cows compared to un-supplemented cows at the low PA, but were similar between supplementation levels at the high PA. The PI was unaffected by the PA, whereas the substitution rate was 0.68 in cows at the low PA and 1.35 in cows at the high PA. Corn silage supplementation may improve the total DM intake and milk production of dairy cows grazing in temperate annual pastures, but only at a low PA.

Effects of corn silage inclusion in preweaning calf diets

The objective of this research was to evaluate the effects of corn silage inclusion in starter feed provided to calves after birth through weaning at 7 wk of age. Thirty-six heifer calves and 9 bull calves were individually housed in hutches. Calves in treatment groups received pasteurized milk with all calf starter, 25% calf starter and 75% corn silage, or all corn silage. Values were recorded daily for feed intake and health, which included fecal, respiratory, and attitude scores; and at wk 2, 4, and 8 for concentrations of serum protein, hematocrit, and serum β-hydroxybutyrate. Body weight, withers height, and hip height were measured at wk 2, 4, 8, and 52. Nine bull calves (3/treatment) were killed at 8 wk of age for assessment of rumen and intestinal tissue morphology. Feed intake and average daily gain were not different among treatments. Least squares means of rumen papillae lengths were significantly different and decreased as corn silage inclusion increased. Crypt depths and total thickness of epithelium were reduced for the corn silage group. Least squares means of body weight, heart girth, hip height, withers height, serum protein, hematocrit, and β-hydroxybutyrate concentrations did not differ among treatments. These data indicated that the mixture of corn silage and starter did not affect growth, feed intake, or intestinal morphology but did affect rumen wall morphology. Feeding solely corn silage as starter feed stunted the growth of rumen papillae and tended to impair intestinal morphology, indicating that only calf starter or a mixture of calf starter and corn silage is more appropriate.

청보리사일리지 및 옥수수사일리지 급여가 육성기 재래 흑염소의 영양소 이용률, 성장 및 혈액성상에 미치는 영향

*ABSTRACTThis study examined the effects of feeding whole-crop barley silage(BS), corn silage(CS) and the mixture of BS and CS(CB) on feed consumption, daily gain, nutrients apparent digestibilities and blood parameters in order to investigate the feed evaluation in Korean black goats. BS, CS, and CB were fed to twelve Korean black goats, which were allocated into three groups in metabolic cages according to the latin-square design. As a result, dry and organic matter intakes for goats per day have shown a tendency to decrease in the order of CS, CB and BS, but there were no significant differences. We also found a similar tendency when the intakes of crude protein, crude fat, and non-fiber carbohydrates(NFC) were examined. However, ADF and NDF consumptions showed a decreasing tendency in the order of CB, BS and CS. Dry matter intakes per metabolic body weight showed the decreasing tendency in the order of CS (57.6g), CB(53.8g) and BS(52.7g), however with no statistical differences. Average daily gain of 64.2g in CB was significantly higher than the other groups(42.0g to 46.0g). Nitrogen intakes and nitrogen retention showed a decreasing tendency in the order of CS, CB and BC. Nevertheless, nitrogen retention in CS group was higher by 30% than that of the BC group with p<0.05. Apparant digestibilities of dry and organic matters were 72.6 and 72.8% for the CS group respectively, which were significantly higher than those of the BS group(67.5 and 69.0%) and the CB group(66.0 and 67.1%). In conclusion, the results of this study demonstrated that the CS group showed more positive feed consumption, digestibility, and nitrogen retention in Korean black goats than those of BS group. The CB group, however, showed similar results to the results of the CS group.(Key words: Whole-crop barley silage, Corn, Silage, Apparant digestibility, Growth performance, Nutrients intakes)

Effects of essential oils on milk production, milk composition, and rumen microbiota in Chios dairy ewes

The effect of the addition of an essential oil (EO) preparation (containing a mixture of natural and nature-identical EO) on the performance of dairy ewes of the Chios breed was investigated. Eighty lactating ewes were allocated into 4 equal groups in a randomized block design, each with 4 replicates of 5 ewes housed in the same pen. The 4groups were fed the same total mixed ration allowance, the roughage being a mixture of corn silage, lucerne hay, and wheat straw, and the concentrate based on cereals and oil cakes. Control ewes were fed their daily allowance of total mixed ration without any EO. The other 3groups were supplemented with EO at levels of 50, 100, and 150mg/kg of the concentrated feed, respectively. Individual milk yield was recorded daily and feed refusals were recorded on a pen basis weekly during the first 5 mo of lactation. Milk samples were analyzed for chemical composition, somatic cell count, and urea content. Rumen samples were analyzed for pH, NH3-N content, and protozoa, cellulolytic, hyper-ammonia-producing, and total viable bacteria counts. Results showed that inclusion of EO increased milk production per ewe, the effect being dose dependent [1.565, 1.681, 1.876, and 2.119 L/d (standard error of the difference ± 0.176) for the control, 50, 100, and 150mg of EO/kg of concentrate diets, respectively], and thus improved feed utilization. Although the inclusion of EO did not affect milk composition, it lowered urea concentration and somatic cell count in milk samples at the highest supplementation level compared with the control. Total counts of viable and cellulolytic bacteria and protozoa were not influenced by EO supplementation; however, counts of hyper-ammonia-producing bacteria were decreased at the 2 highest supplementation levels compared with the control group. Rumen pH was not affected by EO supplementation, but rumen NH3-N was reduced at the highest EO supplementation level, and acetate rumen concentrations tended to decrease and propionate to increase in a dose-dependent manner. In conclusion, EO supplementation may improve feed utilization and performance of the high-yielding dairy Chios ewes; however, the underlying mechanisms leading to this improvement merit further investigation.

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.

Effect of Live Yeast and Mannan-oligosaccharides on Performance of Early-lactation Holstein Dairy Cows

This study evaluated the effects of live yeast and yeast cell-wall mannan-oligosaccharide supplementation on performance and nutrient digestibility during early lactation in cows fed a diet based on a mixture of corn silage and alfalfa hay as forage sources. Eight multiparous Holstein dairy cows (average days in milk, 27±6) were used in a replicated 4×4 Latin square design. Diets contained 45% forage and 55% concentrate on a dry matter (DM) basis and treatments were: i) basal diet without additive (Control), ii) basal diet with 32 g/d of mannan-oligosaccharides (MOS), iii) basal diet with 1.2×10 10 colony forming units per day (cfu/d) of live yeast (Saccharomyces cerevisiae CNCM 1-1077; SC), and iv) basal diet with a mixture of MOS (32 g/d) and SC (1.2×10 10 cfu/d; MOS+SC). Treatments had no effect (p>0.05) on DM intake and yields of milk, 3.5% fat-(FCM) and energy-corrected milk (ECM), and on milk fat percentage, body condition score and blood metabolites. Compared with the Control, only supplementation of SC resulted in numerically higher yields of FCM (41.9 vs. 40.1 kg/d) and ECM (41.8 vs. 40.3 kg/d), and milk fat percentage (3.64 vs. 3.43%). While the MOS diet had no effects on performance compared to the Control, the combination treatment MOS+SC increased milk protein percentage (p<0.05). Also, the MOS supplementation, both alone or in combination with SC, numerically increased milk fat percentage. The SC supplementation increased apparent digestibility of DM and crude protein while the MOS supplementation did not affect digestibility. Concentrations of total volatile fatty acids (VFA) and ruminal pH were similar across treatments. Overall results indicated that supplementation of MOS produced variable and inconsistent effects on rumen metabolism and performance, whereas SC supplementation improved nutrient digestibility and numerically increased FCM and ECM yields, which could not be enhanced by the

The Effect of Silage and Concentrate Type on Intake Behavior, Rumen Function, and Milk Production in Dairy Cows in Early and Late Lactation

The objective of this experiment was to evaluate the effect of feeding total mixed rations (TMR) that differ in structural and nonstructural carbohydrates to dairy cows in early and late lactation on short-term feed intake, dry matter intake (DMI), rumen fermentation variables, and milk yield. A 5×5 Latin square experiment with 15 dairy cows was repeated during early and late lactation. The 5 treatments were a TMR with (all on dry matter basis) 55% roughage (a 50:50 mixture of corn silage and grass silage) and 45% concentrate (a 50:50 mixture of concentrate rich in structural carbohydrates and concentrate rich in nonstructural carbohydrates; treatment CON), a TMR with the concentrate mixture and 55% grass silage (RGS) or 55% corn silage (RCS), and a TMR with the roughage mixture and 45% of the concentrate rich in structural carbohydrates (CSC) or the concentrate rich in nonstructural carbohydrates (CNS). Meal criteria, determined using the Gaussian-Gaussian-Weibull method per animal per treatment, showed an interaction between lactation stage and treatment. Feed intake behavior variables were therefore calculated with meal criteria per treatment-lactation stage combination. Differences in feed intake behavior were more pronounced between treatments differing in roughage composition than between treatments differing in concentrate composition, probably related to larger differences in chemical composition and particle size between corn silage and grass silage than between the 2 concentrates. The number of meals was similar between treatments, but eating time was greater in RGS (227 min/d) and lesser in RCS (177 min/d) than the other treatments. Intake rate increased when the amount of grass silage decreased, whereas meal duration decreased simultaneously. These effects were in line with a decreased DMI of the RGS diet vs. the other treatments, probably related to the high neutral detergent fiber (NDF) content. However, this effect was not found in CSC, although NDF content of the TMR, fractional clearance rate of NDF, and fractional degradation rate of NDF was similar between CSC and RGS. Rumen fluid pH was lesser, and molar proportions of acetic acid and of propionic acid were lesser and greater, respectively, in RCS compared with all other diets. Milk production did not differ between treatments. There was no effect of type of concentrate on milk composition, but diet RCS resulted in a lesser milk fat content and greater milk protein content than diet RGS. Lactation stage did affect short-term feed intake behavior and DMI, although different grass silages were fed during early and late lactation. The results indicate that short-term feed intake behavior is related to DMI and therefore may be a helpful tool in optimizing DMI and milk production in high-production dairy cows.

The Effects of Nitrogen and Forage Source on Feed Efficiency and Structural Growth of Prepubertal Holstein Heifers

Eighty Holstein heifers averaging 189.6 ± 6.8kg of BW were used to evaluate the effects of forage level and rumen degradable nitrogen source on feed efficiency and structural growth. A randomized complete block design was used with heifers blocked according to BW (≤ 136.0kg and > 136.0 kg) and assigned to 1 of 4 treatment diets in a 2 x 2 factorial design. Treatments were constructed with 2 levels of forage (65 or 75%) and 2 nitrogen sources. Forage sources were a mixture of corn silage and chopped timothy hay. Nitrogen sources were either soybean meal (SBM) or a slow-release, polymer-coated urea product (Optigen 1200, CPG Nutrients, Syracuse, NY), which was fed at 1.8% of diet DM on low-forage diets and at 1.3% of diet DM on high-forage diets. Average daily gain and feed efficiency did not differ between rations of different forage level or nitrogen source, averaging 0.87 ± 0.05kg and 7.4 ± 0.5, respectively, across treatments. Similarly, no differences were observed in change of withers height, hip height, hip width, or heart girth. No differences were observed in plasma urea nitrogen, which averaged 12.3 ± 0.4 mg/dL across treatments. Results of this experiment suggest that feeding moderately different levels of forage along with either SBM or a polymer-coated urea product does not result in any significant differences in feed efficiency or structural growth. Polymer-coated urea can be used in heifer diets to effectively replace SBM as a nitrogen source in either low- or high-forage nations.

Avaliação da silagem de capim papuã (Brachiaria plantaginea) por meio do desempenho de bezerros de corte confinados

O experimento teve como objetivo estudar os parâmetros relativos ao desempenho de bezerros de corte em confinamento, alimentados com três dietas, contendo diferentes fontes de volumoso: SPSI - silagem de capim papuã (Brachiaria plantaginea) sem inoculante bacteriano, SPCI - silagem de capim papuã com inoculante bacteriano e SMMS - mistura de silagem de milho (Zea mays) e silagem de sorgo (Sorghum bicolor). Foram utilizados 36 bezerros com média de peso vivo inicial de 159kg e média de idade de sete meses. O confinamento compreendeu 105 dias de avaliação, sendo divididos em cinco períodos de 21 dias. A relação volumoso:concentrado foi de 65:35 para todas as dietas testadas. O uso de inoculante bacteriano, na silagem de papuã, não afetou (P&gt;0,05) as variáveis estudadas. Não houve interação (P&gt;0,05) entre fonte de volumoso e período de avaliação para os consumos médios de matéria seca (CMS) e de energia digestível (CED), expressos em kg dia-1 e Mcal dia-1 (CMSD e CEDD), por 100kg de peso vivo (PV) (CMSP e CEDP) e por unidade de tamanho metabólico (CMSM e CEDM), ganho de peso médio diário (GMD), conversão alimentar (CA) e eficiência energética (EE). A análise de contraste entre as dietas que incluíam silagem de capim papuã (SPSI + SPCI) contra a que incluía a mistura de silagem de milho e sorgo (SMMS) revelou que os animais alimentados com silagem de capim papuã apresentaram menor CMSD (4,99 contra 5,56kg dia-1) sem diferença para o CMSP e CMSM, menor GMD (0,800 contra 1,061kg dia-1) e pior CA (6,26 contra 5,30) em relação à mistura de silagens de milho e sorgo.

Milk Production and Composition from Cows Fed High Oil or Conventional Corn at Two Forage Concentrations

Twelve multiparous Holstein cows (63±24 d in milk) were used in a replicated 4×4 Latin square with 28-d periods to evaluate conventional and high oil corn grains when fed at two different forage-to-concentrate ratios. Dietary treatments consisted of conventional or high oil corn supplementing a diet with a 25:25:50 mixture of corn silage: alfalfa: concentrate mix, or a high forage diet with a 30:30:40 mixture of corn silage: alfalfa: concentrate mix. Dry matter intake (28.1, 28.7, 26.9, and 26.2kg/d for normal diets with conventional and high oil corn, and high forage diets with conventional and high oil corn, respectively) and milk yields (36.8, 37.2, 35.5, and 35.2, kg/d) were similar for conventional and high oil corn diets and were lower with the high forage diet, regardless of corn source. Milk fat concentrations were greater when cows were fed diets containing 60% forage (4.03 vs. 3.88%, for the 60 and 50% forages, respectively), but milk protein concentrations were not affected by forage content. Corn source did not affect milk fat or protein concentrations. Long-chain fatty acid concentrations, unsaturated fatty acid concentrations, and total 18:1 fatty acid concentrations were greater when cows were fed high oil corn but were unaffected by forage content of the diet. Concentrations of transvaccenic acid (0.58, 0.81, 0.62, and 0.69g/100g of fatty acids) and cis-9, trans-11 conjugated linoleic acid (0.28, 0.39, 0.32, and 0.33g/100g of fatty acids) were greater when cows were fed high oil compared with conventional corn when fed 50% forage but were similar for both corn sources at 60% forage. Total n-3 fatty acids were not affected by corn source or forage content. High forage diets decreased milk production and increased milk fat concentration. Feeding high oil corn increased concentrations of long-chain, unsaturated, transvaccenic, and conjugated linoleic fatty acids in milk; however, production of transvaccenic and conjugated linoleic acids were attenuated by high forage diet.

Urinary pH and mineral excretion of cows fed four different forages supplemented with increasing levels of an anionic compound feed

Effects of progressive supplementation of four different basal forage diets with a compound feed having a high negative cation/anion difference (about −750 meq./kg dry matter (DM)) on urinary pH and urinary mineral excretion was evaluated in dry cows. Four diets made up of 6 kg DM/day forage (Italian ryegrass (R), meadow hay (M), mixture of corn silage (C) and R or alfalfa (A) and R) and 3 kg DM/d of a compound feed, were offered in equal portions at 8.00 and 16.00 h to four dry, non-pregnant Friesian cows. Diets and cows were arranged in a 4×4 Latin Square design having experimental periods of 21 days. In each period, starting from the afternoon meal of day 11, the compound feed was gradually substituted in three 1 kg increments with the same compound feed supplemented with anionic salts. Interactions between type of forage and concentrate were significant for urinary pH values. Urine pH decreased at an increasing rate after anionic feed supplementation at different rates for the different of basal forage diets, with the lowest value for R and the highest for A diet. The 1 and 2 kg levels of substitutions elevated urinary Cl and urea concentrations, but not Na and K concentrations or urine volume: thus the osmolality increased from 266 to 334 mOsm/kg. The highest level of anionic feed supplementation (3 kg) sharply changed urine output patterns with increased urine volumes from 3.14 to 4.63 l/6 h and lowered urinary Cl and urea concentrations resulting in reduced urine osmolality from 334 to 277 mOsm/kg. The anionic compound feed caused a marked increase of the Ca concentration in urine, from 0.96 to 4.30 mmol/l, while P levels were not affected. Overall the anionic supplementation caused a progressive increase in urinary output of Cl and Ca (577–1085 and 2.50–15.53 mmol/6 h, respectively), while only the highest level of anionic compound feed resulted in significant increases in urea, Na and K outputs. Given the different effect of dietary forages on the pH decline of urine after anionic supplementation, the metabolic acidotic condition in close up dry cows should be monitored by the urinary pH to calibrate the dosage of anionic compound feed.

Effects of Forage Species on Milk Protein Production by Lactating Dairy Cows11Supported by federal Hatch funds and the College of Agricultural and Life Sciences, University of Wisconsin, Madison, WI 53706.

Abstract Eighteen multiparous early lactation Holstein cows were assigned to a replicated 3 × 3 Latin square with 28-d periods to evaluate milk protein production potential when corn silage ( CS ) or small grain silage ( SGS ) was added to diets based on alfalfa silage ( AS ). Treatments consisted of all AS, a mixture of AS and CS, or a mixture of AS and SGS. Treatment diets were isonitrogenous, isofibrous, and contained maximal amounts of carbohydrates to challenge the milk protein production of cows under intensive milk production systems fed these forages. Lactation performance, milk composition, nutrient intakes, and diet digestibilities were measured. There were no significant differences in milk yield of the cows fed diets containing AS, CS, or SGS. Cows fed diets containing all AS-produced milk with a higher fat percentage than did cows fed CS, and cows fed diets containing all AS produced more milk fat and protein than cows fed CS or SGS. There were no significant differences in the percentage of casein, whey protein, or true protein in milk when cows were fed AS, CS, or SGS. There were also no significant differences in the percentage or production of lactose or solids-not-fat when cows were fed diets containing different silages. Similarly, there were no significant differences in DMI or dietary DM digestibility by cows when fed diets containing different silages. Data suggest that adding CS or SGS to AS-based diets does not improve DMI, lactation performance, or milk protein production of lactating cows.

CARCASS TISSUE YIELD AND DISTRIBUTION IN THREE BIOLOGICAL TYPES OF CATTLE FED GRAIN OR FORAGE-BASED DIETS

One hundred and eighty-nine steers comprising 63 small (S) rotational crossbreds, 66 large (L) rotational crossbreeds and 60 Holsteins (H) were fed either a concentrate diet based on corn silage and high-moisture corn, or a forage diet based on a mixture of corn silage and alfalfa haylage. All steers were fed ad libitum and slaughtered to cover a range in external fatness (0–15 mm subcutaneous fat). Steers were removed from feed 36 h and water 16 h prior to slaughter. The left side of each carcass was separated into depot fat, lean and bone. At the same proportion of subcutaneous fat (63 g/kg carcass), S and L carcasses had greater proportions of carcass lean (P &lt; 0.001), but less fat (P &lt; 0.01) and bone (P &lt; 0.001) than carcasses from H Steers. Small and large carcasses had greater muscle to bone ratios (P &lt; 0.001) than carcasses from H steers. Diet had no effect on lean tissue proportions, but forage feeding increased carcass bone (P &lt; 0.001) and decreased carcass fat (P &lt; 0.01). Forage feeding also resulted in carcasses with lower muscle to bone ratios (P &lt; 0.01) than carcasses produced from grain feeding. Holstein-carcasses had more carcass fat partitioned into the body cavity depot and less into the subcutaneous depot than S and L carcasses, but diet had no effect on fat partitioning. Biological type (S, L or H) and diet were found to have a minor effect on fat distribution. The results are discussed with reference to carcass evaluation of beef and dairy cattle fed diets based on forage or grain. Key words: Biological type, diet, carcass composition, carcass grading

Individual Versus Group Feeding of Constant Versus Variable Forage:Concentrate of Total Mixed Rations Through Two Lactations and Intervening Dry Period

Total mixed rations were fed for ad libitum consumption to four groups of cows through two lactations and intervening dry period. Treatments were: 1) group fed 50:50 (roughage:concentrate, dry matter) ration, 2) individually fed 50:50 ration, 3) individually fed 65:35 ration, and 4) individually fed 50:50 ration for 150 days postpartum and an 80:20 ration thereafter and through the dry period. Roughage was a 4:1 mixture of corn silage:grass-legume silage. Of the original 31, 11, 11, and 11 cows on treatments 1 to 4; 22, 11, 7, and 9 cows refreshened for second lactations. Fatty degenerated livers were in 5, 2, 1, and 0 cows that died soon after refreshing. Weight gains between freshening and the end of the dry period during first lactation were 151, 153, 115, 101kg. No treatment differences were found in 305-day yields of milk or milk components. Results indicate a disadvantage to feeding high concentrate treatments through the lactation and dry period.

COMPARISONS OF DIFFERENT FORAGE FEEDING SYSTEMS FOR DAIRY COWS

Four different forage feeding systems were compared for milk production efficiency using 40 Holstein cows divided into four equal groups and assigned to the different forage rations for 3 consecutive yr. Two groups grazed on a ladino-timothy pasture for 130 days; for the 235 days of winter season the first group (PH) was fed ad libitum timothy-red clover hay, while the second group (PC) received ad libitum corn silage and 3 kg of hay per cow per day. The other two groups were kept in confinement; one (CA) was fed a mixture of corn silage and alfalfa-timothy silage in a 1:1 ration on a dry matter (DM) basis, the other (CR) was fed a complete ration consisting on a DM basis of 30% corn silage, 30% alfalfa-timothy silage and 40% concentrate. Concentrate was fed to the PH, PC and CA groups according to the level of milk fat production. Daily DM intake and fat-corrected milk (FCM) production were 17.4, 17.2, 14.9, 15.1 kg/cow and 18.2, 19.2, 19.1, 19.1 kg/cow, for groups PH, PC, CA and CR, respectively. Feed to FCM ration was higher (P &lt; 0.05) for PH than PC which was higher (P &lt; 0.05) than CA and CR cow groups. Milk fat production was lower (P &lt; 0.05) for PH than for other systems. Average yearly FCM and hectare required per cow, when allowing for land required for concentrate production, were 3417, 3905, 4403, 3502 kg/ha and 1.45, 1.44, 1.29, 1.64 ha/cow/yr for groups PH, PC, Ca and CR, respectively. Health and breeding status were also recorded for each cow.