Increase In Dry Matter Intake Research Articles

The influence of reproductive physiology and nutrient supply on the periparturient relaxation of immunity to the gastrointestinal nematode Trichostrongylus colubriformis in Merino ewes

A pen experiment was conducted to investigate the interaction of early-weaning and nutrient supply on the periparturient relaxation of immunity to the gastrointestinal nematode (GIN) Trichostrongylus colubriformis in Merino ewes. Mixed-age pregnant and non-pregnant (dry) ewes were infected with 8,000 T. colubriformis L3/week, and fed either a high or low quality diet. Following parturition, lambs were either removed from their mothers at 2 days of age or allowed to continue suckling. Systemic immunity began to wane during late pregnancy with circulating eosinophils and plasma total antibody (Ab) levels declining from day −37 (relative to the midpoint of lambing) and day −24, respectively. Pregnant ewes fed the low quality diet exhibited an increasing faecal worm egg count (WEC) from day −24 and had higher intestinal worm burdens on day 13, whereas ewes fed the high quality diet had a delayed transient rise in WEC of lower magnitude. Dry and early-weaned ewes remained highly resistant to T. colubriformis at all times. In the post-lambing/lactation period, ewes fed the high quality diet had higher levels of local total Ab and numbers of goblet cells (GC) in the small intestine on days 13 and 41. Lactating/suckled ewes had a lower anti-parasite local immune response as indicated by reduced titres of total Ab, IgG1, IgM and IgA and lower numbers of mucosal mast cells (MMC), globule leukocytes (GL) and GC in small intestinal tissue compared to their dry and early-weaned counterparts. Early-weaning resulted in rapid recovery of blood eosinophils and total Ab. On day 13 post-lambing, titres of total Ab, IgG1, IgM, IgA and IgE, and numbers of MMC and GL were greater than those measured in dry and suckled ewes. When fed the high quality diet, ewes had a higher dry matter (DM) intake, maternal weight, fat score, greater fat depth and eye muscle depth, birthed heavier lambs that had higher growth rates, and produced more milk. The physiological status of pregnancy resulted in a higher DM intake but lower measures of fat depth and eye muscle depth, and suckling led to an increase in DM intake but a reduction in body weight and fat score through mobilisation of fat and muscle reserves. Despite the marked effect of diet quality on production traits, some inconsistencies were observed between body composition and apparent parasite resistance, measured by WEC and worm counts, suggesting that the nutritional influence was not necessarily always mediated through changes in body composition. Although reproductive status affected blood leptin levels, diet had no effect within suckled ewes and therefore it was concluded that leptin has no causative role in maintaining the periparturient relaxation of immunity to T. colubriformis.

Effects of dietary Astragalus polysaccharide and Astragalus membranaceus root supplementation on growth performance, rumen fermentation, immune responses, and antioxidant status of lambs

The aim of this study was to investigate effects of dietary Astragalus membranaceus root (AMT) and Astragalus polysaccharide (APS) supplementation on growth performance, blood metabolites, rumen fermentation, immune responses and antioxidant status of weaned lambs. Twenty-four male Ujumqin weaned lambs (a local breed) with average age of 60±10.3d and similar genetic background were randomly assigned to one of three treatments for a 30d feeding period. Treatments consisted of the lambs’ basal diets with addition of: (1) nothing (control), (2) 15g/kg APS or (3) 50g/kg AMT of the diet (dry matter (DM) basis). Blood samples were collected at day 0 and 30 and ruminal fluid samples at day 0, 15 and 30. Results showed that APS supplementation increased DM intake of lambs (P=0.003), but that average daily gain, feed efficiency and apparent digestibility of nutrients did not differ among treatments. Concentrations of ammonia N (P=0.004) and total volatile fatty acids (P=0.005) were affected by an interaction between treatment and feeding time. Both APS and AMT feeding increased propionic acid (P=0.025) which resulted in a reduction in the acetic acid to propionic acid ratios in ruminal fluid (P=0.014). Feeding APS and AMT increased total antioxidant capacity (P<0.001) and total superoxide dismutase activities (P<0.001), and decreased cortisol levels (P<0.001) in plasma. However, blood plasma metabolites such as blood urea N, high and low density lipoprotein–cholesterol, triglyceride, glucose and total protein, which are reflective of animal metabolism, were not affected by APS and AMT feeding. Only dietary AMT supplementation affected immune responses, including increased immunoglobulin M production (P<0.001) and lymphocyte numbers (P=0.024) in whole blood. Results suggest that APS and AMT feeding mainly improved antioxidant capacity and affected rumen fermentation patterns of lambs, while AMT supplementation affected immunity, but both additives failed to improve apparent digestibility of nutrients in weaned lambs.

The effect of N-fertilisation rate or inclusion of red clover to timothy leys on fatty acid composition in milk of dairy cows fed a commercial silage : concentrate ratio

The aim of this experiment was to, under typical Swedish production conditions, evaluate the effects of grass silages subjected to different N-fertilisation regimes fed to dairy cows on the fatty acid (FA) composition of their milk, and to compare the grass silages in this respect to red clover-dominated silage. Grass silages made from first year Phleum pratense L. leys subjected to three N-fertilisation regimes (30, 90 and 120 kg N/ha, designated G-30, G-90 and G-120, respectively) and a mixed red clover–grass silage (Trifolium pratense L. and P. pratense L.; 60/40 on dry matter (DM) basis, designated RC–G) were produced. The experiment was conducted as a change-over design, including 24 primiparous and multiparous dairy cows of the Swedish Red breed, each of which was allocated to three of the four diets. The cows were offered 11 kg DM of silage and 7 kg concentrates. The silages had similar DM and energy concentrations. The CP concentration increased with increase in N-fertilisation level. There was a linear increase in DM intake of the different silages with increased N fertilisation. There were also differences in concentrations of both individual and total FAs amongst silages. The daily milk production (kg/day) did not significantly differ between treatments, but G-30 silage resulted in higher concentrations of 18:2n-6 in the milk compared with the other two grass silages. The highest concentrations of 18:3n-3 and cis-9, trans-11 18:2 were found in milk from cows offered the RC–G silage. The G-30 diet resulted in higher concentration of 18:2n-6 and the same concentration of 18:3n-3 in the milk as the other grass silages, despite lower intake levels of these FAs. The apparent recoveries of 18:3n-3 from feed to milk were 5.74%, 4.27%, 4.10% and 5.31% for G-30, G-90, G-120 and RC–G, respectively. A higher recovery when red clover is included in the diet confirms previous reports. The higher apparent recovery of 18:3n-3 on the G-30 treatment may be related to the lower silage DM intake, which led to a higher relative proportion of ingested FAs originating from concentrates compared with the G-90 and G-120 diets. With the rates and types of concentrates used in this study, the achieved differences in FA composition among the silages were not enough to influence the concentrations of unsaturated FAs in milk.

Soybean as supplement of growing cattle on tropical pasture: effects on intake, digestibility and animal performance

&lt;p&gt;An indoor trial was conducted with weaning heif­ers (experiment 1). Raw whole soybean (RSB), whole soybean heated with steam (SHSB) and extruded whole soybean (EXSB) were given as supplements at 0.7% of live weight (LW). One group was the control, with no supplement. All supplements increased total dry matter (DM) intake and did not affect hay intake. RSB was the most degradable crude protein (CP) source. Total digestive tract digestibility was not affected by treatments, except for apparent CP digestibility. Because total DM intake increased in supplemented animals, all supple­ments increased intake of digestible DM, organic matter (OM) and CP over the control. In another assay (experiment 2) a performance trial was conducted with forty weaned heifers. The same supplements used in experiment 1 were used. Heifers supplemented with EXSB gained the highest and had better apparent feed efficiency. Apparent feed efficiency was similar to those observed in protein supplementation, suggesting that some increase in DM intake from pasture may have occurred. RSB had the poorest apparent feed efficiency which agreed with the numerical lower OM intake observed in experiment 1. All supplemented heifers had higher gain, hip height change, thoracic perimeter and body condition score change than the control group.&lt;/p&gt;

Changes in rumen absorption processes during transition

Transition is defined as the period from 3 weeks before parturition until 3 weeks postpartum and is characterized by changes in endocrine status and by major alterations in the requirement for nutrients, vitamins and minerals. At parturition, the dry period diet is replaced by an ad libitum offered lactation diet, which causes changes of rumen fermentation because of its higher energy density and the overall increase of dry matter intake. Hence, ruminal fermentation parameters such as pH, volatile fatty acid (VFA) concentrations and osmotic pressure are changed. This causes alterations in the rumen epithelium generally termed adaptation: the modulation of enzyme activities, an increase in the number and size of papillae and enhanced transport rates of ions. These effects are well documented when sheep or cows are experimentally and independent of parturition shifted from a low energy (roughage) to a concentrate diet. Only a few studies have been conducted in cows during transition and, thus, data on diet dependent effects on postpartum rumen acidosis are absent and information regarding number and size of papillae is inconsistent. Furthermore, investigations of gene expression related to VFA absorption or metabolism have not shown diet dependent alterations. However, evidence from in vitro and in vivo studies exists that the stimulation of fermentation before parturition enhances the transport rates of Na, Cl and VFA across bovine rumen epithelium. The underlying mechanisms for epithelial adaptation to dietary alterations are poorly understood at present. Luminal factors such as increased VFA concentrations (particularly butyrate) and the hormonal effects of insulin and of insulin like growth factor 1 have partly been confirmed to be involved in the regulation of this adaptation process. More research is needed in order to determine the factors causally inducing adaptational responses and the amount of dietary change at which the adaptational responses apparently level off. Despite these uncertainties, an increase of energy and protein intake undoubtedly improves the barrier and transport functions of the epithelium. Consequently, at least for 2 weeks before parturition, a diet should be offered that is fermented more easily and more rapidly than the diet in the early dry period. Furthermore, efforts should be directed towards an improved voluntary food intake before and after parturition, with special attention being paid to the mechanisms enabling the epithelium to adapt to and handle the regular diurnal variations in pH, VFA concentration and osmotic pressure, mechanisms that seem to fail in the pathophysiology of subacute rumen acidosis.

Effect of supplementation on the performance of F1 crossbred goats finished in native pasture

The present study aimed to assess the effect of supplementation on the performance of F1 (Boer × females of no defined breed) goats finished in native pasture. The experiment was conducted at the Universidade Federal de Campina Grande, Patos Campus, Paraíba, Brazil, with twenty-four 120-day-old non-castrated F1 (Boer × NDB) male goats, with a 15.52 kg live weight (LW). Animals were distributed in four levels of supplementation (0.0; 0.5; 1.0; 1.5% of body) and six replicates. In order to perform the evaluation of dry matter availability, the herbaceous vegetation was divided into grass and herbaceous dicotyledon and evaluated at the beginning (5/28/2007), in the middle (7/9/2007) and at the end (8/6/2007) of the experiment. In the beginning of the experiment, the availability of grass dry matter was 1,102.89 kg/ha, and at the end of the experiment, the availability of the referred matter was greater (1,494.81); on the other hand, the opposite occurred for the dicotyledons, with a dry matter content of 1,759.46 kg/ha in the beginning of the experiment, and only 236.76 kg/ha at the end of the experiment. Supplementation made it possible to estimate the increase in dry matter intake of 257.15 g/day and of 20.79 g/kg0.75/day, as well as the daily weight gain of 103 g for each percentage point increase that resulted from supplementation. The availability and nutritional quality of forage had a strong influence on the effect of supplementation on dry matter intake, with a negative response for supplementation levels of up to 0.74% of the live weight Consequently, the finishing of F1 crossbred goats in a grazing area in the Caatinga can be improved with the supplementation of concentrate at levels 1.0 to 1.5% of the live weight.

Effect of rumen-protected choline on performance, blood metabolites, and hepatic triacylglycerols of periparturient dairy cattle

The effects of a dietary supplement of rumen-protected choline on feed intake, milk yield, milk composition, blood metabolites, and hepatic triacylglycerol were evaluated in periparturient dairy cows. Thirty-eight multiparous cows were blocked into 19 pairs and then randomly allocated to either one of 2 treatments. The treatments were supplementation either with or without (control) rumen-protected choline. Treatments were applied from 3 wk before until 6 wk after calving. Both groups received the same basal diet, being a mixed feed of grass silage, corn silage, straw, and soybean meal, and a concentrate mixture delivered through transponder-controlled feed dispensers. For all cows, the concentrate mixture was gradually increased from 0kg/day (wk −3) to 0.9kg of dry matter (DM)/d (day of calving) and up to 8.1kg of DM/d on d 17 postcalving until the end of the experiment. Additionally, a mixture of 60g of a rumen-protected choline supplement (providing 14.4g of choline) and of 540g of soybean meal or a (isoenergetic) mixture of 18g of palm oil and 582g of soybean meal (control) was offered individually in feed dispensers. Individual feed intake, milk yield, and body weight were recorded daily. Milk samples were analyzed weekly for fat, protein, and lactose content. Blood was sampled at wk −3, d 1, d 4, d 7, d 10, wk 2, wk 3, and wk 6 and analyzed for glucose, nonesterified fatty acids, and β-hydroxybutyric acid. Liver biopsies were taken from 8 randomly selected pairs of cows at wk −3, wk 1, wk 4, and wk 6 and analyzed for triacylglycerol concentration. We found that choline supplementation increased DM intake from 14.4 to 16.0kg/d and, hence, net energy intake from 98.2 to 109.1 MJ/d at the intercept of the lactation curve at 1 day in milk (DIM), but the effect of choline on milk protein yield gradually decreased during the course of the study. Choline supplementation had no effect on milk yield, milk fat yield, or lactose yield. Milk protein yield was increased from 1.13 to 1.26kg/d at the intercept of the lactation curve at 1 DIM, but the effect of choline on milk protein yield gradually decreased during the course of the study. Choline supplementation was associated with decreased milk fat concentration at the intercept of the lactation curve at 1 DIM, but the effect of choline on milk fat concentration gradually decreased as lactation progressed. Choline supplementation had no effect on energy-corrected milk yield, energy balance, body weight, body condition score, and measured blood parameters. Choline supplementation decreased the concentration of liver triacylglycerol during the first 4 wk after parturition. Results from this study suggest that hepatic fat export in periparturient dairy cows is improved by choline supplementation during the transition period and this may potentially decrease the risk for metabolic disorders in the periparturient dairy cow.

Effect of legume (Phaseolus calcaratus) hay supplementation on rumen microorganisms, fermentation and nutrient digestibility in swamp buffalo

The objective of this research was to evaluate the effect of Phaseolus calcaratus hay (PCH) supplementation on the intake, digestibility, rumen fermentation, microbial population (bacteria, protozoa, and fungi) and methane production in swamp buffaloes fed on rice straw based diet. Four, 2.5year old rumen fistulated male buffaloes were randomly assigned according to a 4×4 Latin square design. The treatments were level of PCH supplementation at 0, 300, 600 and 900g DM/hd/d as supplements. The PCH contained 18.3% crude protein (CP) and 2.8% condensed tannins (CT). All buffaloes were fed with rice straw ad libitum while additional concentrate (12.6% CP) was fed at 0.3% body weight (BW). The study revealed that PCH supplementation had no effect on rumen temperature, pH, NH3-N and blood urea N. Volatile fatty acid (VFAs), especially those of propionic acid and acetic acid concentrations in the rumen were maximized (P<0.05) at 600g/hd/d feeding level. However, concentrations of each VFA and the acetate to propionate ratio did not differ among treatments. Bacterial, protozoal and fungal zoospore populations were maximized (P<0.05) at the intermediate PCH feeding levels. Rumen methane gas production was decreased linearly (P<0.05) with increasing level of PCH supplementation. N utilization in the buffaloes differed among treatments, with PCH supplementation linearly increasing N retention and efficiency of microbial N supply. Furthermore, PCH supplementation linearly increased (P<0.05) in terms of total DM intake, apparent digestibility of CP and OM, while, DM, NDF and ADF digestibilities were not affected. Supplementation of PCH at 600g/hd/d was beneficial in swamp buffaloes fed rice straw as a basal roughage, as it resulted in increased DM intake, reduced protozoal and methane gas production in the rumen, increased N retention as well as efficiency of rumen microbial CP synthesis.

Feed conversion efficiency and marginal milk production responses of pasture-fed dairy cows offered supplementary grain during an extended lactation

A study was conducted to quantify the feed conversion efficiency (FCE) and marginal milk responses of pasture-fed cows offered supplementary grain during an extended lactation of 670 days. The experiment used three groups of 10 Holstein cows in four experimental periods of 4 weeks, beginning when cows were ~60, 240, 420 and 530 days in milk (DIM). In each experimental period, cows were individually fed diets of either freshly cut perennial ryegrass pasture supplemented with triticale (60 and 420 DIM), or pasture silage and lucerne hay supplemented with wheat (240 and 530 DIM). On each occasion, one of the three groups was offered additional grain at 0.0, 2.5 or 5.0 kg DM/cow.day. Milk production was measured daily and concentrations of milk fat and protein weekly. These data were used to calculate FCE and marginal responses of milk, energy-corrected milk and milk solids (fat + protein). Results showed FCE was highest at 60 DIM and lowest at 530 DIM. Increased DM intake because of increased grain intake led to increased FCE at 240 and 530 DIM when the energy concentration of forage was lowest. Marginal milk responses were not different at any stage of lactation. For milk solids and energy-corrected milk, responses at 240 DIM were the same as at 530 DIM, but greater than at 60 DIM and 420 DIM. This study provides the first Australian data about FCE and marginal milk production responses to grain supplementation of pasture-fed cows undergoing an extended lactation. The results should provide farmers with confidence that good responses to grain can be achieved even in the latter part of a 22-month lactation.

Supplementation with whole cottonseed changes milk composition and milk fatty acid profile in dairy cows

Eight multiparous Holstein cows in mid lactation (average days in milking of 160 ± 40) were used in a replicated 4 by 4 Latin square design, each experimental period lasting 3 weeks, to determine the effects of whole cottonseed (WCS) treatment and dietary crude protein (CP) concentration on the profile of milk fatty acids. Each 3-week experimental period consisted of 2 weeks for ration adaptation followed by 1 week for data collection. The experimental diets consisted of: (1) Control (without WCS), 16% CP; (2) 20% WCS, 16% CP; (3) 20% WCS, 13% CP; and (4) 20% crushed WCS, 13% CP. Minerals and vitamin supplements were the same in all experimental diets. The WCS treatment led to increased DM intake, fat-corrected milk yield, fat concentration, proportion of long-chain fatty acids, unsaturated fatty acids and ratio of unsaturated to saturated fatty acids (P &lt; 0.05). Decreased concentration of dietary CP from 16 to 13% (diet 2 compared with diet 3) led to a decrease in both milk yield and milk composition (P &lt; 0.05). WCS crushed in diets with 13% CP (diet 4 compared with diet 3) increased (P &lt; 0.05) the concentration of conjugated linoleic acid in milk fat. The results demonstrated that adding WCS to the diet of lactating cows improves both milk yield and milk fatty acid profile, particularly the proportion of conjugated linoleic acid.

Effects of season and body condition on appetite, body mass and body composition in ad libitum fed pony mares

Changes in appetite, body mass (BM), body condition score (BCS), direct (ultrasonographic) and indirect (deuterium oxide dilution technique) measures of body fat were monitored in Welsh Mountain pony mares (n=11, 5-19 years of age) offered ad libitum access to a complete diet (gross energy 16.9±0.07 MJ/kg dry matter) for 12 weeks during summer (n=6; 246±20 kg) and winter (n=5; 219±21 kg). At the outset, each group comprised two thin (BCS 1-3/9), moderate (BCS 4-6/9) and obese (BCS 7-9/9) animals. For ponies that were non-obese at the outset, BM was gained more rapidly (P=0.001) in summer (0.8±0.1 kg/day) than winter (0.6±0.0 kg/day). This was associated with a seasonal increase in dry matter intake (DMI) which became maximal (summer, 4.6±0.3% BM as DMI/day; winter, 3.5±0.1% BM as DMI/day) during the second month. The appetite of the obese ponies was half that reported for non-obese animals in the summer and BM remained constant irrespective of season. Body 'fatness' increased progressively for non-obese but not obese ponies. Body fat content was exponentially associated with increasing BCS but BCSs >6 were not useful indicators of actual body fat. Endogenous circannual mechanisms to suppress winter weight gain were insufficient to prevent the development of obesity in ad libitum fed ponies.

Effects of feeding increasing levels of wet corn gluten feed on production and ruminal fermentation in lactating dairy cows

An experiment was conducted to evaluate the effects of increasing dietary inclusion rates of wet corn gluten feed (WCGF; Sweet Bran; Cargill Inc., Blair, NE) on milk production and rumen parameters. Four primiparous and 4 multiparous ruminally cannulated Holstein cows averaging 90±13 d in milk (mean ± SD) were randomly assigned to 1 of 4 sequences in a replicated 4 × 4 Latin square experiment with 28-d periods. Treatments were diets containing 0, 11, 23, and 34% WCGF on a dry matter basis; alfalfa hay, corn silage, corn grain, soybean meal, expeller soybean meal, and mineral supplements were varied to maintain similar nutrient concentrations across diets. Performance and measures of ruminal fermentation were monitored. Linear and quadratic effects of increasing WCGF inclusion rate were assessed using mixed-model analysis. Increasing dietary WCGF linearly increased dry matter intake (26.7, 25.9, 29.3, and 29.7 kg/d for 0, 11, 23, and 34% WCGF, respectively) and milk production (36.8, 37.0, 40.1, and 38.9 kg/d). Concentrations of milk components did not differ among treatments; however, protein and lactose yields increased linearly and fat yield tended to increase linearly when more WCGF was fed. This led to greater production of energy-corrected milk (38.2, 38.8, 41.7, and 40.4 kg/d) and solids-corrected milk (35.2, 35.7, 38.5, and 37.2 kg/d), but efficiency of production linearly decreased. Increased WCGF in the diet tended to linearly decrease ruminal pH (6.18, 6.12, 6.14, and 5.91), possibly because mean particle size was below typical recommendations for all diets, and diets with greater proportions of WCGF had a smaller mean particle size. Ruminal acetate concentration decreased linearly and propionate increased linearly as WCGF inclusion rate increased. Treatments had a quadratic effect on ammonia concentration, with greater concentrations for the 0 and 34% WCGF diets. In situ digestibility of soybean hulls showed a significant diet-by-time interaction, and increasing dietary levels of WCGF linearly decreased in situ neutral detergent fiber disappearance at 24h. Change in body condition score increased linearly with increasing WCGF inclusion rate. Results indicate that adding WCGF to dairy rations can increase energy-corrected milk yield, and this increase appears to be driven, at least in part, by an increase in dry matter intake.

Evaluation of wheat or corn dried distillers’ grains with solubles on performance and carcass characteristics of feedlot steers

A study was conducted on crossbred steers (n = 275; 376 ± 24 kg) to evaluate performance and carcass quality of cattle fed wheat or corn dried distillers’ grains with solubles (DDGS). The control ration contained 86.6% rolled barley grain, 5.7% supplement and 7.7% barley silage (DM basis). The four treatments included replacement of barley grain at 20 or 40% of the diet (DM basis) with wheat or corn DDGS. Steers were slaughtered at a common end weight of 645 kg with 100 steers randomly (n = 20 per treatment) selected for determination of the retail yield of sub-primal boneless boxed beef (SPBBB). Data were analyzed as a completely randomized design using pen as the experimental unit. Feeding increasing levels of wheat DDGS led to a quadratic increase in dry matter intake (DMI) (P &lt; 0.01), whereas increasing levels of corn DDGS led to a quadratic decrease in DMI (P = 0.01). Average daily gain was not influenced (P = 0.13) by feeding wheat or corn DDGS, but cattle fed corn DDGS exhibited a quadratic increase (P = 0.01) in gain:feed. As a result, a quadratic increase (P &lt; 0.01) in calculated NEg of the diet was observed as corn DDGS levels increased. A linear decrease (P = 0.04) in days on feed (169, 166 and 154 d) was noted when increasing levels of wheat DDGS (0, 20 and 40%) were fed. Dressing percentage increased in a linear fashion with wheat DDGS (P &lt; 0.01) inclusion level and in a quadratic fashion (P = 0.01) as corn DDGS inclusion level increased although other carcass traits were not affected (P &gt; 0.10) by treatment. The results indicate that replacement of barley grain with corn or wheat DDGS up to 40% of the diet (DM) can lead to superior performance (improved gain:feed or reduced days on feed, respectively) with no detrimental effect on quality grade or carcass SPBBB yield.Key words: Dried distillers’ grains with solubles, corn, wheat, feedlot performance, carcass quality, steers

Performance of weaner rabbits fed with varying levels of Tridax Procumbens(L)forage

Twenty four weaner rabbits (mongrel breed) of both sexes with average weight of 350g were fed formulated diet comprising 0, 15, 30 and 45% Tridax procumbens (TRP). The parameters evaluated were nutrient intake, daily weight gain, feed, conversion ratio, incidences of diarrhoea and mortality. At the end of the study, internal organ weight and dressing percentages were determined. Analysis indicated a significant (P 0.05) affected by the dietary treatments. As the level of TRP increased in the diet, there was significant (P < 0. 05) increase in dry matter intake and feed conversion ratio among the dietary treatment, while the daily weight gain decreased with increase in TRP inclusion level. It was concluded that weaner rabbits can tolerate up to 45% level of TRP in their diet without any adverse effect on their performance. Key Words: Tridax procumbens , weaner rabbits, performance

Effects of mixtures of red clover and maize silages on the partitioning of dietary nitrogen between milk and urine by dairy cows

Eight multiparous lactating Holstein–Friesian cows were used to evaluate the partitioning of dietary nitrogen (N) from diets based on mixtures of red clover and maize silages in comparison with diets based on ryegrass silage. All cows received 4 kg/day of a standard dairy concentrate with one of four forage treatments in an incomplete changeover design with three 4-week periods. Three treatments were based on mixtures of red clover and maize silage. N intake was altered both by varying the ratio of these silages (40/60 and 25/75 on a dry matter (DM) basis) and by an additional treatment for which the DM intake of the 40/60 mixture was restricted to the level achieved with grass silage. Rumen passage rates were estimated from faecal excretion curves following a pulse oral dose of Dysprosium-labeled silage and urinary excretion of purine derivatives (PD) was used as an index of rumen microbial protein synthesis. Red clover silage mixtures led to significantly increased feed intake (21.5, 20.7 and 15.2 kg DM/day for 40/60 and 25/75 red clover/maize silage mixtures and grass silage, respectively), milk production (25.8, 27.8 and 20.0 kg/day for the same treatments, respectively) and milk component yields, but were without effect on milk fat and protein concentrations. The large increase in the yield of milk (24.5 kg/day) and milk components for the restricted red clover/maize silage treatment, in comparison with the grass silage treatment, was proportionately greater than the increase in DM intake (16.6 kg DM/day). There were no significant treatment effects on diet digestibility, while the higher intakes of red clover silage mixtures were associated with higher rumen passage rates (5.82%, 6.24% and 4.55%/h, respectively). There were significant effects of both N intake and forage source on the partitioning of dietary N between milk and urine. When dietary protein was diluted by the inclusion of maize silage, red clover silage led to increased milk N and reduced urinary N in comparison with grass silage. Improvements in N utilisation may be related to increased dietary starch and/or rumen passage rates leading to increased microbial protein synthesis for these treatments. Urinary excretion of PD was significantly higher for all diets based on mixtures of red clover and maize silages, in comparison with grass silage. Urinary N output was close to literature predictions based on N intake for the diet based on ryegrass silage, but 40 to 80 g/day (25% to 30%) less than predicted for the diets based on the mixtures of red clover and maize silages.

Chemical composition, rumen degradability, protein utilization and lactation response to selected tree leaves as substitute of cottonseed cake in the diet of dairy goats

The aim of this study was to investigate the potential of leaves from Grewia oppositifolia ( G. oppositifolia) and Ziziphus mauritiana ( Z. mauritiana) as a crude protein (CP) supplements to low quality diets of goats in Pakistan. Chemical composition and CP degradability of the tree leaves were compared with cottonseed cake (CSC). The CP content of the supplements ranged from 141 to 269 g/kg dry matter (DM). Contents of total phenols and condensed tannins (CT) were higher (P<0.01) in Z. mauritiana than G. oppositifolia 49, 33 and 20, 0.6 g/kg DM, respectively. Leaves from G. oppositifolia were higher (P<0.05) in Ca (35 g/kg DM). The rate of degradation and effective degradability of CP at rumen outflow rates of 0.04 and 0.06/h were consistently higher (P<0.05) in CSC than in the leaves. Tree leaves did not vary from each other in N disappearance characteristics. A balance trial in a 4 × 4 Latin square design was conducted with four dry Beetal goats (35 ± 2.3 kg body weight (BW)). The goats were fed on range grass hay as a sole diet or supplemented with CSC, G. oppositifolia or Z. mauritiana on an iso-N basis. Addition of the supplements to the diets increased DM intake and N retention (P<0.05) without affecting DM digestibility. N retention in goats varied (P<0.05) due to diet composition and was highest (6.2 g) with Z. mauritiana. Lactation responses were examined with 16 Beetal goats (44.6 ± 4.20 kg BW; days in milk 44 ± 2.4), assigned randomly to a supplement of CSC, G. oppositifolia, Z. mauritiana or mixture of both. All goats received a basal diet of maize silage ad libitum and were daily grazed on natural pasture for about 4 h. Yield of milk differed among the supplements and was highest (P<0.05) for Z. mauritiana. Among the supplements, a high (P<0.05) milk fat content of 56 g/kg milk was recorded with CSC and G. oppositifolia. Total solids, protein and solids not fat concentrations in the milk did not respond to supplementation. We conclude that Z. mauritiana and G. oppositifolia leaves can replace CSC as a supplement in low quality diets of dairy goats.

Effect of propylene glycol supplementation on microbial protein production in transition dairy cows

Limited research suggests that propylene glycol (PG) supplementation can have inhibitory effects on ruminal microbes. Our hypothesis was that PG supplementation would reduce microbial protein production. The objective of this study was to determine the effect of PG supplementation on microbial protein production in transition dairy cows. Sixteen pregnant cows (seven primiparous and nine multiparous) were paired based on expected calving dates and then randomly assigned within each pair to either a basal diet (control) or basal diet plus 624 g d-1 of PG. Diets were fed twice daily for ad libitum intake, and PG was fed in equal amounts as a top dress from day -7 to day 45 (transition period). Sample collection was carried out at three time intervals starting at day -14 ± 5, day 15 and day 38 relative to calving, with the first collection period (day -14 ± 5) being the pretreatment period. Propylene glycol supplementation had no effect on total urine purine derivatives (PD; allantoin + uric acid) excretion; consequently, microbial N supply, estimated using total urinary PD excretion, was not affected by PG supplementation. There was an increase in urine total PD excretion and, thus, estimated microbial N supply, with time relative to calving. Microbial efficiency did not change with time relative to calving and, therefore, the increase in dry matter intake during the post-partum period led to the increase in estimated microbial N supply. Results from this study indicate that supplementing PG over the transition period had no effect on microbial protein production in the rumen.Key words: Transition dairy cow, propylene glycol, microbial protein production

Effect of dietary protein concentration and degradability on response to rumen-protected methionine in lactating dairy cows

An incomplete 8×8 Latin square trial (4-wk periods; 12 wk total) using 32 multiparous and 16 primiparous Holstein cows was conducted to assess the production response to crude protein (CP), digestible rumen-undegraded protein (RUP), and rumen-protected Met (RPM; fed as Mepron; Degussa Corp., Kennesaw, GA). Diets contained [dry matter (DM) basis] 21% alfalfa silage, 34% corn silage, 22 to 26% high-moisture corn, 10 to 14% soybean meal, 4% soyhulls, 2% added fat, 1.3% minerals and vitamins, and 27 to 28% neutral detergent fiber. Treatments were a 2×2×2 factorial arrangement of the following main effects: 15.8 or 17.1% dietary CP, with or without supplemental rumen-undegraded protein (RUP) from expeller soybean meal, and 0 or 9g of RPM/d. None of the 2- or 3-way interactions was significant. Higher dietary CP increased DM intake 1.1kg/d and yield of milk 1.7kg/d, 3.5% fat-corrected milk (FCM) 2.2kg/d, fat 0.10kg/d, and true protein 0.05kg/d, and improved apparent N balance and DM and fiber digestibility. However, milk urea N and estimated urinary excretion of urea-N and total-N also increased, and apparent N efficiency (milk-N/N-intake) fell from 33 to 30% when cows consumed higher dietary CP. Positive effects of feeding more RUP were increased feed efficiency and milk fat content plus 1.8kg/d greater FCM and 0.08kg/d greater fat, but milk protein content was lower and milk urea N and urinary urea excretion were elevated. Supplementation with RPM increased DM intake 0.7kg/d and FCM and fat yield by 1.4 and 0.06kg/d, and tended to increase milk fat content and yield of milk and protein.

Assessment of dietary ratios of red clover and grass silages on milk production and milk quality in dairy cows

Twenty-four multiparous Holstein-Friesian dairy cows were used in a replicated 4×4 Latin square changeover design experiment to test the effects of changing from ryegrass (Lolium perenne) silage to red clover (Trifolium pratense) silage in graded proportions on feed intakes, milk production, milk organoleptic qualities, and whole-body nitrogen partitioning. Four dietary treatments, comprising ad libitum access to 1 of 4 forage mixtures plus a standard allowance of 4 kg/d dairy concentrates, were offered. The 4 forage mixtures were, on a dry matter (DM) basis: 1) 100% grass silage, 2) 66% grass silage: 34% red clover silage, 3) 34% grass silage: 66% red clover silage, and 4) 100% red clover silage. In each of 4 experimental periods, there were 21 d for adaptation to diets and 7 d for measurements. There was an increase in both DM intakes and milk yields as the proportion of red clover in the diet increased. However, the increase in milk yield was not as great as the increase in DM intake, so that the efficiency of milk production, in terms of yield (kg) of milk per kg of DM intake, decreased. The concentrations of protein, milk fat, and the shorter chain saturated fatty acids decreased, whereas C18 polyunsaturated fatty acids (PUFA) and long-chain PUFA (C20+) increased as the proportion of red clover in the diet increased. There was little effect of dietary treatment on the organoleptic qualities of milk as assessed by taste panel analysis. There were no effects on the aroma of milk, on aftertaste, or overall liking of the milk. Milk was thicker and creamier in color when cows were fed grass silage compared with red clover silage. The flavor of milk was largely unaffected by dietary treatment. In conclusion, increasing the proportion of red clover in the diet of dairy cows increased feed intakes and milk yields, decreased the concentration of fat and protein in milk, increased PUFA for healthiness, and had little effect on milk organoleptic characteristics.

Effect on Production of Replacing Dietary Starch with Sucrose in Lactating Dairy Cows

Replacing dietary starch with sugar has been reported to improve production in dairy cows. Two sets of 24 Holstein cows averaging 41kg/d of milk were fed a covariate diet, blocked by days in milk, and randomly assigned in 2 phases to 4 groups of 6 cows each. Cows were fed experimental diets containing [dry matter (DM) basis]: 39% alfalfa silage, 21% corn silage, 21% rolled high-moisture shelled corn, 9% soybean meal, 2% fat, 1% vitamin-mineral supplement, 7.5% supplemental nonstructural carbohydrate, 16.7% crude protein, and 30% neutral detergent fiber. Nonstructural carbohydrates added to the 4 diets were 1) 7.5% corn starch, 0% sucrose; 2) 5.0% starch, 2.5% sucrose; 3) 2.5% starch, 5.0% sucrose; or 4) 0% starch, 7.5% sucrose. Cows were fed the experimental diets for 8 wk. There were linear increases in DM intake and milk fat content and yield, and linear decreases in ruminal concentrations of ammonia and branched-chain volatile fatty acids, and urinary excretion of urea-N and total N, and urinary urea-N as a proportion of total N, as sucrose replaced corn starch in the diet. Despite these changes, there was no effect of diet on microbial protein formation, estimated from total purine flow at the omasum or purine derivative excretion in the urine, and there were linear decreases in both milk/DM intake and milk N/N-intake when sucrose replaced dietary starch. However, expressing efficiency as fat-corrected milk/DM intake or solids-corrected milk/DM intake indicated that there was no effect of sucrose addition on nutrient utilization. Replacing dietary starch with sucrose increased fat secretion, apparently via increased energy supply because of greater intake. Positive responses normally correlated with improved ruminal N efficiency that were altered by sucrose feeding were not associated with increased protein secretion in this trial.