Effect of forage to concentrate ratio and duration of feeding on growth and feed conversion efficiency of male lambs

Rations (DM basis) for spring-born male lambs consisting of concentrates ad libitum (CON), 50:50 (50% concentrate:50% forage), and forage ad libitum (FORG) were evaluated across feeding periods of three durations (36, 54, and 72 d). Lambs on CON diets were offered ad libitum access to concentrate along with 400 g of fresh weight silage (daily), while 50:50 diets were offered 0.9 and 3.0 kg of concentrate and silage, respectively. Lambs on FORG were offered ad libitum access to 25.5% DM silage. These rations were fed to 99 spring-born male Texel cross Scottish Blackface lambs which were assigned to a 3 × 3 factorial arrangement. Lambs were slaughtered following completion of their respective treatments. Lambs fed CON diets had greater ADG, FCE, and carcass weight (P < 0.001) and carcasses with greater conformation score (P < 0.001) than lambs fed 50:50 or FORG diets. Duration of feeding had no effect on production variables across all three concentrate inclusion levels. It was concluded that the inclusion of concentrates is needed to adequately finish lambs fed indoors. Feeding lamb’s 50:50 diets resulted in modest responses and may be a viable option for finishing lambs or to maintain growth in lambs when the cost of concentrate feed is high relative to the financial return on the lamb meat.

Effect of backgrounding and transition diets on fecal concentration and strain types of commensalEscherichia coliin beef cattle

Su, R., Munns, K., Beauchemin, K. A., Schwartzkopf-Genswein, K., Jin-Quan, L., Topp, E. and Sharma, R. 2011. Effect of backgrounding and transition diets on fecal concentration and strain types of commensal Escherichia coli in beef cattle. Can. J. Anim. Sci. 91: 449–458. The aim of the study was to assess the effect of four different backgrounding diets [55% corn silage in combination with 40% of either temper rolled barley-grain, wheat dried distillers' grain, corn dried distillers' grain or millrun (dry matter basis)] and a transition diet containing increasing amount of concentrate (60 to 90%) on fecal Escherichia coli in feedlot heifers. Heifers were fed backgrounding forage based diets for 91 d and then were shifted to a transition diet for an additional 18 d. Strain characterization of E. coli (n=224) was carried out at time time points over 109 d and indicated that heifers fed the barley–grain diet shed higher (P<0.001) total and tetracycline-resistant (Tetr) E. coli in the backgrounding phase. Of the total E. coli examined (n=224), 70.3% showed resistance to one or more of the 14 antimicrobials examined, which increased to 82.3% by day 109. Among the recovered E. coli, 23 phenotypes and 154 pulsed field gel electrophoresis patterns grouped into 38 clusters indicative of extensive E. coli diversity in heifers. Although supplementation of 40% barley-grain was correlated to higher total E. coli shedding in the backgrounding phase, the backgrounding diets did not influence strain clustering. Strains collected during the transition phase clustered more closely than those collected during the backgrounding phase. This increased strain clustering with high concentrate inclusion in the transition diet was observed within 18 d of the transition phase. Our study indicated variations in E. coli shedding rates and strain clustering in relation to time and diet.

Effect of concentrate: voluminous ratio on the performance of Santa Inês lambs

The experiment was carried out in the sheep division of Universidade Federal de Lavras, aiming to evaluate the effect of different concentrate : voluminous ratio on the performance of Santa Inês lamb after wean. 40 lambs, male uncastrated, were used and fed with four different diets: diet A (100% concentrate), diet B (75:25 concentrate : voluminous) , diet C (50:50 concentrate : voluminous) , diet D (25:75 concentrate : voluminous). The experimental diets were isoproteic, differing only on its levels of concentrate : voluminous and balanced to meet the nutritional demands according to the recommendation of the Agricultural Research Council (1980). The experimental period was not pre-established, because it corresponded to the necessary period for the last lamb to reach the live weight of 35kg. The dry matter consumption (DMC), crude protein consumption (CPC), fiber in neutral detergent consumption (FNDC) and fiber in acid detergent consumption (FADC), were affected by the different concentrate : voluminous ratio, in which, the animals that received diets with higher concentrate inclusion presenting better results for the variables related to the development. The lambs fed with the diet containing higher inclusion of voluminous did not present weight gain, on the contrary, presented weight loss, since none of the animals reached slaughter weight and the mortality rate was extremely high (80%).

The response of dairy cows of high genetic merit to increasing proportion of concentrate in the diet with a high and medium feed value silage

Forty-eight high genetic merit Holstein/Friesian dairy cows with Predicted Transmitting Abilities for milk fat plus protein yield, calculated using 1995 as the base year (PTA95 fat plus protein), of 40·0 kg, were used in an eight treatment, two period (period length = 8 weeks) change-over design experiment. Diets were offered ad libitum in the form of a complete diet. Treatments comprised a high and medium feed value silage, with concentrates being incorporated into the diet at proportional inclusion rates of 0·10, 0·30, 0·50 and 0·70 of total dry matter with the high feed value silage, and at 0·32, 0·48, 0·64 and 0·80 of total dry matter with the medium feed value silage. The high feed value silage was produced from a primary regrowth herbage (regrowth interval of 33 days) which was wilted prior to ensiling, while the medium feed value silage was produced from a primary growth herbage harvested on 9 June 1995. The high and medium feed value silages had estimated metabolizable energy concentrations of 12·4 and 11·3 MJ/kg DM respectively. Animals commenced treatments after a mean post calving interval of 26 days.Irrespective of silage feed value, total dry matter intake and milk yield tended to increase with increasing proportion of concentrate in the diet. Milk protein concentrations increased to concentrate inputs of 0·50 and 0·64 of total DM with the high and medium feed value silages respectively, but decreased at the highest concentrate inclusion rates. Milk fat concentrations tended to decrease at higher concentrate inclusion rates. The milk yield responses to increasing proportion of concentrate in the diet have been described by a pair of significantly different equations: Y = 34·2−11·9×0·0101x and Y = 34·2−28·5×0·0101x for the high and medium feed value silages respectively (where Y = milk yield (kg/day) and x = concentrate proportion in the diet on a dry matter basis). Similarly, milk fat and milk protein yields for the two silage types have been described by pairs of significantly different equations. Using these milk yield response equations, it can be calculated that at a concentrate proportion in the diet of 0·32 total dry matter, an additional 3·7 kg of milk per day would be produced by offering the high, rather than the medium feed value silage, while at a concentrate proportion of 0·70 total dry matter, the milk yield benefit associated with the high feed value silage was reduced to 0·6 kg per day. Similarly, total dry matter intakes for animals offered the high feed value silage were 7·4 and 0·8 kg per day greater than for animals offered the medium feed value silage, at concentrate proportions in the diet of 0·32 and 0·70 total dry matter, respectively. These responses indicate that at low concentrate inclusion rates in the diet, silage feed value has a major influence on animal performance, while at higher concentrate inclusion rates, the importance of silage feed value is reduced.

Maize silage, grain sorghum silage and forage sorghum silage in diets with different proportions of concentrate for the finishing of weaner lambs.

The potential of diets, based on maize silage (M), non-bird-resistant grain sorghum silage (NBRGS), bird-resistant grain sorghum silage (BRGS) and forage sorghum silage (FS), in different proportions with concentrate for each silage, was evaluated for the finishing of weaner lambs. On a dry basis the ratios of silage: concentrate were 70: 30, 60:40, 50:50, 40: 60 and 30: 70 respectively for each of the silages. The concentrate mixtures were composed of different quantities of maize meal and soya-bean oilcake meal in order to balance the crude protein contents of the different diets used from weaning to 35 kg live weight and from 35 kg live weight to slaughter at 140 and 110 g/kg respectively.Better apparent digestibilities of dry matter, crude protein and acid-detergent fibre as well as food conversion to live weight were found for diets with M or NBRGS as roughage sources compared with those with BRGS and FS as roughage sources. At the lower levels of concentrate inclusion in the diets the dressing proportions, carcass grades and food conversion to carcass weight for the diets with M and NBRGS as roughage sources were also better than were those with BRGS and FS as roughage sources. Although higher levels of concentrate inclusion in the diets to a large extent rectified these biological disadvantages of the diets based on BRGS and FS, they will also cause a rise in the price of the diet.

An examination of the effect of method and level of concentrate feeding on milk production in dairy cows offered a grass silage-based diet

An experiment was conducted to examine the effect of method and level of concentrate feeding on milk production characteristics in dairy cows offered a grass silage-based diet. Twelve treatments were used with 24 Holstein/Friesian dairy cows in a four-period change-over design experiment. Treatments consisted of three methods of concentrate feeding (twice daily, four times daily or complete diet) and four levels of concentrate feeding (2, 4, 6 or 8 kg/day). Offering a complete diet significantly reduced silage substitution rate (0·28 kg silage dry matter (DM) per kg concentrate DM) compared with concentrates offered twice daily (0·50 kg silage DM per kg concentrate DM; P < 0·01). Method of concentrate feeding had no significant effect on milk yield or milk fat concentration (P > 0·05), although the response in milk protein concentration to increased concentrate food level was significantly greater with twice and four times daily concentrate feeding than with complete diet feeding (0·59, 0·56 and 0·44 g/kg per kg increase in concentrate food level; P < 0·05). Increasing concentrate inclusion level significantly reduced silage DM intake (P < 0·001) but significantly increased (P < 0·001) total DM intake. Milk yield and milk protein concentration were significantly increased (P < 0·001) and milk fat concentration significantly reduced (P < 0·02) with increasing concentrate inclusion level. Total ration apparent digestibility coefficients were unaffected (P > 0·05) by either method of feeding or concentrate inclusion level. However, modified acid-detergent fibre apparent digestibility decreased significantly with increasing concentrate inclusion (P < 0·01). Results suggested that offering complete diets, with concentrates comprising on average 0·33 of total DM intake, increased both silage and total DM intake although this was not reflected in either increased milk yield or improvements in milk composition.

A comparison of starchy and fibrous concentrates for milk production, energy utilization and hay intake by Friesian cows

SummaryTwenty-four Friesian cows were allocated to one of four diets for weeks 3–14 of lactation following 2 weeks on a common diet. The diets (kg air-dry feed/day) were 7–2 kg hay and 10·8 kg either starchy or fibrous concentrates (60S and 60F) or 3·5 kg hay and 14·0 kg either starchy or fibrous concentrates (80S and 80F). Rumen samples were taken by stomach tube in weeks 10 and 12 of lactation and the digestibility of the diets was measured with four cows per treatment during weeks 13 and 14. The digestibility of the same feeds was also measured in sheep at maintenance.The principal carbohydrate constituents of the concentrates were barley, wheat and cassava in the starchy concentrates and citrus pulp, sugar-beet pulp and wheat feed in the fibrous concentrates. The concentrates were designed to have similar concentrations of metabolizable energy (ME) and the diets were planned to provide similar intakes of digestible energy and crude protein.Milk yield and composition were very similar for treatments 60S and 60F. With the higher proportion of starchy concentrates (80S), milk yield was about 20% greater than on 60S, fat concentration fell severely but protein and lactose concentrations were unaffected. With the higher proportion of fibrous concentrates (80F), milk yield and the protein and lactose concentration were similar to values on 60F but fat concentration was lower, though not nearly so low as on 80S. Milk energy yield was reduced by the higher proportion of concentrates but was unaffected by type of carbohydrates. Live-weight changes were small.In both the sheep, consuming at maintenance, and the lactating cows consuming at about 3 times maintenance, digestibility of dry matter, organic matter and energy was higher with the higher concentrate diets but was unaffected by type of concentrate. The digestibility of fibre was greater with the fibrous concentrates but the effect of level of concentrate inclusion was inconsistent. Digestibility coefficients were consistently lower for the lactating cows than for the sheep.The proportion of acetic acid in the rumen volatile fatty acids in the cows was higher and the proportion of propionic acid was lower with the fibrous concentrates. The differences were much greater with the higher proportion of concentrates.During weeks 15–22 of lactation the cows were reallocated to concentrate treatments and given hay ad libitum. Hay intake was about 1 kg/day higher with the fibrous concentrates but the difference was not significant. Hay intake fell by about 0·6 kg/kg concentrate intake for both concentrate types. No significant differences in milk yield or composition were established, probably because of incomplete adaptation even after 8 weeks.It is concluded that at concentrate intakes of about 10 kg/day, the source of carbohydrate in the concentrates has little effect on milk production when the concentrates are of similar ME concentration. However, at higher levels of concentrate inclusion, although the diets may have similar ME concentrations, important differences in the yields of fat, protein and lactose occur due to carbohydrate source and these can be related to differences in rumen fermentation.