Higher Dry Matter Intake Research Articles

Nutrients intake, digestibility, nitrogen balance and growth performance of sheep fed different silages with or without concentrate

The experiment was conducted to investigate the influence of maize (Zea mays), sorghum (Sorghum bicolor) and millet (Pennisetum americannum) silages with or without concentrate on nutrients intake, digestibility, nitrogen balance and weight gain in Sipli sheep. Six experimental diets were formulated having 100% maize silage (MS), maize silage and concentrate as 50:50 (MSC), 100% sorghum silage (SS), sorghum silage and concentrate as 50:50 (SSC), 100% millet silage (MiS) and millet silage and concentrate as 50:50 (MiSC), respectively. For this purpose, 24 Sipli lambs were randomly allotted to six experimental diets in a completely randomized design for 90 days, four lambs per diet. The results indicated that among various silage diets, lambs fed MS diet consumed higher dry matter (DM) than those fed SS and MiS diets. Likewise, lambs offered MSC had higher dry matter intake than those fed SSC and MiSC diets. Crude protein (CP) and neutral detergent fibre (NDF) consumed by the lambs also followed the similar trend. Higher DM, CP and NDF digestibilities were also observed in lambs fed MS and MSC diets than those fed SS, SSC, MiS and MiSC diets. Overall digestibilities of DM, CP and NDF were higher in experimental diets containing silage with concentrate. Lambs fed MS diet had 2.79 g/day and 4.45 g/day higher N retention than those fed SS and MiS, respectively. Similarly, lambs fed MSC diet had 2.24 g/day and 5.12 g/day higher N retention than those fed SSC and MiSC diets, respectively. The results showed that lambs fed MSC gained more daily weight gain had better feed conversion ratio than those fed MS, SS, SSC, MiS and MiSC diets. The findings of the present study indicated that lambs fed MSC diet had higher nutrients intake, digestibility, nitrogen balance and weight gain.

Effects of whey and molasses as silage additives on potato hash silage quality and growth performance of lambs

The aim of the study was to determine the effect of whey or molasses on the fermentation quality when added to potato hash silage. In addition, lamb performance, digestibility and feed intake of diets containing potato hash silage were compared with a diet containing maize silage (MSd). Potato hash silage (treated with no additive, or whey, or molasses) and MS were produced in 210 L drums for 90 days and the fermentation quality of the silages was determined thereafter. Diets were formulated and fed ad libitum to 32 South African Dorper lambs (23.5 ± 0.873 kg live weight) for 63 days. A digestibility study was conducted during the last week of the study. The untreated potato hash silage (UPHS) was poorly fermented as indicated by higher concentrations of butyric acid, ammonia-N and pH compared to the other silages. Higher dry matter intake (DMI) and daily weight gains (218 and 250 g/d) were obtained with MSd and molasses treated potato hash silage diet (MPHSd) compared to the other diets. Nutrient digestibility was lower in the UPHS diet compared to the other dietary treatments. It was concluded that the fermentation quality of potato hash was improved with the addition of whey and molasses. Furthermore, growth performance was higher with the MSd and MPHSd than of the other treatments, suggesting that MPHSd can safely replace MSd in a lamb diet at a dietary inclusion level of 20% without any adverse effect on animal performance.Keywords: Digestibility, dry matter, fermentation, intake, maize silage

Effect of frame score on performance and carcass characteristics of steers finished in the feedlot or backgrounded for various time on pasture and finished in the feedlot

Abstract. A two-year data of three-year study integrating pasture and drylot feeding systems was used to examine effect of frame score on performance and carcass characteristics of steers. Each year, 84 fall-born and 28 spring-born calves of similar genotypes were used. Fall-born and spring-born calves were started on test in May and October, respectively. Treatments were: 1) fall-born calves directly into feedlot; 2 and 3) fall-born calves put on pasture with or without an ionophore and moved to the feedlot at the end of July; 4 and 5) fall-born calves put on pasture with or without an ionophore and moved to the feedlot at the end of October; 6 and 7) spring-born calves put on pasture with or without an ionophore and moved to the feedlot at the end of October. Frame scores were determined by taking steers’ age and live weight into consideration. Cattle that grazed the same duration on pasture were regarded as the same treatment regardless of whether they received an ionophore or not. In the feedlot, steers were provided an 82 % concentrate diet containing whole-shelled corn, ground alfalfa hay, and a protein, vitamin and mineral supplement containing ionophore and molasses. Pens of cattle were harvested at approximately 522 kg. Cattle having a higher frame score at the entry to pasture and grazed until July and October tended to have higher and lower daily gain on pasture than those having lower frame score, respectively (P>0.05). Fall-born and spring-born cattle grazed until October, which had higher frame scores at the entry to pasture tended to have higher daily gain in the feedlot showing a compensatory growth. In the feedlot, within each treatment cattle having higher frame score tended to have higher daily gain (P>0.05) and had higher dry matter intake (P<0.05). Cattle spending longer time in the feedlot have better carcass quality and higher yield grades. Results showed that cattle with higher frame scores had higher growth potentials in the feedlot and if the grazing season is extended then daily gain of cattle having higher frame score decreases.

Eating and rumination behaviour in Brahman grade cattle and crossbred water buffalo fed on high roughage diet

The purpose of this study is to compare feeding and other behavior and nutrient digestibility of tropical grade Brahman (body weight (BW) = 231 kg ± 12.4; n = 3) and crossbred water buffalo (BW = 300 kg ± 13.9; n = 3). This experiment on digestibility and measures of muscles of mastication utilized one-way, and animal behavior two-way, analysis of variance, respectively. Two video camcorders were installed in each pair of buffalo and Brahman for 24 h period programmed on the 107th, 109th and 111th days of the digestion trials. Frequency and duration of feeding, meal intake, rumination, bolus, chews, drinking, defecating, standing and lying were recorded daily. Muscle diameter of Digastricus, Masseter and Pterygoid and different regions of the tongue were sampled and measured under light microscope using a standard micrometer. Buffalo obtained significantly higher intake of dry matter, roughage, crude protein, total digestible nutrient and metabolized energy than Brahman. This was supported by longer meal duration (P ≤ 0.05), and shorter meal breaks (P ≤ 0.05) of buffalo than Brahman. The diameter of the muscles for mastication was bigger (P ≤ 0.05) in buffalo than in Brahman, which is indicative of stronger chewing ability. Briefly, lesser and slower chewing action; higher intake of roughage and crude protein; and longer resting behavior of crossbred water buffalo than Brahman are all indicative of better digestive and metabolic performance of the buffalo under high roughage feeding conditions.

A model to optimise the requirements of lactating dairy cows for physically effective neutral detergent fibre

This study modelled multiple physiological responses of dairy cows to physical and chemical characteristics of a diet aiming to optimise their requirements for physically effective neutral detergent fibre, expressed inclusive of particles-dry matter > 8 mm (peNDF>8). Extensive research data, comprising a wide range of feeding conditions (n = 64 studies and 257 different dietary treatments), were used to parameterise the model, while statistical modelling was used to account for the inter- and intra-experiment variation as well as to derive the model estimates. Physiological thresholds and ‘safety limits’ of peNDF>8 for maintaining different physiological variables were derived using non-linear statistical modelling. Results showed that peNDF>8 content in the diet is a key factor stimulating rumination activity, maintaining optimal ruminal pH and promoting fibre digestion. Modelling data with regard to the association of fibre digestion and time duration of ruminal pH < 5.8 and dietary peNDF>8 suggests that feeding of less than 13.7% peNDF>8 (the lower ‘safety limit’) is critical to prevent depression of fibre digestion in dairy cows. The study also indicated that the beneficial effects of peNDF>8 on ruminal pH and fibre digestion can be at the expense of the dry matter intake (DMI) level of high-producing cows when the peNDF>8 threshold of 14.9% in the diet is exceeded. In terms of the optimisation of peNDF>8 requirements, the modelling data suggest that feeding of 17–18.5% peNDF>8 can be beneficial in maintaining ruminal pH, while allowing a relatively high DMI (22.3–22.7 kg · d−1) for average high-producing dairy cows.

Milk yield and composition, feed intake and stocking rate of crossbread cows in tropical grasses managed in a rotational grazing system

The objective of this study was to evaluate milk yield and composition, dry matter intake, and stocking rate in pastures with tanzania grass (Panicum maximum cv. Tanzânia), star grass (Cynodon nlemfuensis cv. Estrela-Africana), and marandu grass (Brachiaria brizantha cv. Marandu). The grasses were managed in a rotational grazing system with Holstein x Zebu crossbreed cows, with a 30-day resting period and three days of paddock occupation. The pastures were fertilized with 1,000 kg/ha/year using the 20:05:20 (NPK) formula, split in three applications during the rainy season. It was used a complete random block experimental design with three factors being studied and two replications. In the experiment, four cows/paddock were used and, when it was necessary, regulator animals were added in order to obtain a supply of 7% body weight green forage dry matter. The animals were individually fed concentrate at 2 kg/day during the experimental period. Milk yield did not differ among the three grasses, with values of 9.1; 9.1; and 8.7 kg/cow/day for pastures with tanzania grass, star grass and marandu grass, respectively. Similarly, grass did not affect milk chemical composition. Stocking rate was similar among the three grasses, with values of 4.6; 4.5 and 5.0 UA/ha for tanzania grass, star grass and marandu grass, respectively. The highest dry matter intake was observed for tanzania grass with 2.6% of the body weight while stargrass (2.3%) and marandu grass (2.4%) did not differ among each other. The highest dry matter intake on tanzania grass pasture was not reflected on milk yield per animal. Milk yield and composition and stocking rate are similar among the evaluated grasses.

A comparison between Holstein-Friesian and Jersey dairy cows and their F1 hybrid on milk fatty acid composition under grazing conditions

The objective of this study was to investigate the effect of 2 breeds, Holstein and Jersey, and their F1 hybrid (Jersey × Holstein) on milk fatty acid (FA) concentrations under grazing conditions, especially conjugated linoleic acid (CLA) and n-3 polyunsaturated fatty acids because of their importance to human health. Eighty-one cows (27 per breed grouping) were allocated a predominantly perennial ryegrass pasture. Samples were collected over 2 periods (June and July). Breed affected dry matter intake and milk production and composition. Holstein cows had the highest dry matter intake (18.4±0.40kg of DM/d) and milk production (21.1±0.53kg of DM/d). Holstein and Jersey × Holstein cows had similar 4% fat corrected milk, fat yield, and protein yield; with the exception of fat yield, these were all higher than for Jersey cows. Milk fat concentration was highest for Jersey cows and lowest for Holstein cows, with the hybrid cows intermediate. Total FA and linolenic acid intake (1.09±0.023 and 0.58±0.012 kg/d, respectively) were highest for Holstein cows. In terms of milk FA, Holstein cows had higher contents of C14:1, cis-9 C18:1 and linoleic acid. In turn, Jersey and Jersey × Holstein cows had higher content of C16:0. Milk concentrations of neither the cis-9,trans-11 isomer of CLA nor its precursor, vaccenic acid, were affected by breed. Nevertheless, large variation between individual animals within breed grouping was observed for CLA and estimated Δ9-desaturase activity. There was some evidence for a negative heterotic effect on milk concentration of CLA, with the F1 hybrid cows having lower concentrations compared with the mid parent average. Plasma FA profile did not accurately reflect differences in milk FA composition. In conclusion, there was little evidence for either breed or beneficial heterotic effects on milk FA content with human health-promoting potential, though significant within-breed, interanimal variation was observed.

The biological and toxicological importance of molybdenum in the environment and in the nutrition of plants, animals and man

The molybdenum intake by German and Mexican adults (21 test populations) aged 20 to 69 years with mixed and ovolactovegetarian diets were determined. Each test group consisted of at least 7 women and 7 men, which collected all consumed foodstuffs and beverages as visually estimated duplicates on 7 successive days. The balance studies were carried out with 8 test populations (women and men) with mixed and ovolactovegetarian diets. People with mixed diet in Germany consumed, on average, 89 (women) and 100 μg Mo/day (men), whereas in Mexico they took in 160 and 210 μg Mo/day, respectively. German ovolactovegetarians consumed ∼175 μg Mo/day. Male adults of Germany consumed 21% more molybdenum than women. This difference is the result of a 24% higher dry matter intake by males. The residence place, its geological origin and time of examination influenced the molybdenum intake significantly (60–115 μg Mo/day). The normative molybdenum requirement of adults amounts to 25 μg/day, with women needing 20 and men 25 μg/day. As a rule approximately only one-third of the absorbed molybdenum is excreted renally, the rest faecally. Breast feeding mothers excreted 11% via milk, 56% faecally and 33% renally. The apparent absorption rate of molybdenum amounted to 37% in humans with mixed and vegetarian diets, whereas it reached 44% in breast-feeding mothers. The calculation of molybdenum consumption (basket method) overestimated the molybdenum intake by 50% in comparison to chemical determination by the duplicate portion method.

Feeding amount affects the sorting behavior of lactating dairy cows

The objective of this study was to determine whether feed sorting behavior in dairy cattle is influenced by the amount of feed provided. Six lactating Holstein cows, individually fed a total mixed ration once daily, were exposed to two treatments in a crossover design with 7-d periods. The treatments were: (1) lower feed amount (LFA; target 10% orts), and (2) higher feed amount (HFA; target 20% orts). Dry matter intake (DMI) was monitored daily for each animal. On the final 4 d of each treatment period, fresh feed and orts were sampled for particle size analysis. The particle size separator had three screens (19, 8, 1.18 mm) and a bottom pan, resulting in four fractions (long, medium, short, fine). Sorting was calculated as the actual intake of each particle size fraction expressed as a percentage of the predicted intake of that fraction. Actual orts percentage averaged 11.5% for the LFA and 18.0% for the HFA treatments. When on the HFA cows sorted for the medium particles to a greater extent than on the LFA (103.0 vs. 101.1%). Further, when on the HFA treatment cows sorted against short particles to a greater extent than on the LFA (95.2 vs. 98.6%). Despite greater sorting on the HFA treatment, the concentrations of neutral detergent fiber (NDF; 29.6%) and starch (27.1%) in the feed consumed were similar between treatments. Given this, and that DMI was greater on the HFA treatment compared with the LFA treatment (29.7 vs. 26.5 kg d-1), greater intakes of NDF (8.7 vs. 7.8 kg d-1) and starch (8.0 vs. 7.2 kg d-1) were also observed on the HFA treatment. The results suggest that, despite causing greater feed sorting, increasing the feeding amount for lactating dairy cows promoted higher DMI and did not prevent the consumption of a ration balanced to meet their nutritional requirements.Key words: Feeding amount, sorting behavior, dairy cow

Effects of Administration of Three Different By-Pass Lipids on Growth Performance, Rumen Activity and Feeding Behaviour of Beef Cattle

A study was carried out on beef cattle to compare three different by-pass lipids administration in relation to their intake, performance, bunk behaviour and rumen fermentation characteristics. Ninety-six Charolaise males were subdivided into three groups. Each group was fed a specific diet including differentiated sources of rumen by-pass fats. The first group received 500 g/head/day of calcium salts (CaS), the second and the third received 420 g/head/day of hydrogenated fatty acids (HF) and triglycerides (AL), respectively. The three by-pass fats differ in fatty acids composition, chain length and mean particle size. AL group had average daily gain significantly greater (P=0.0005) than animals fed calcium soaps. No difference was observed between AL and HF groups (P=0.08) and between HF and CaS groups. Final body weights of AL animals were significantly higher (P=0.005) than CaS group. There were no differences between AL group and HF group and between HF group and CaS group. Average dry matter intake (DMI) was higher (P<0.05) in AL and HF groups compared with CaS group. Feed conversion rate was better for AL and CaS groups (P<0.05) compared with HF group. Evaluating their behaviours in approaching feed, the animals seemed to prefer hydrogenated fats flavour as regard to calcium soaps. No differences were highlighted in ruminal pH and ruminal volatile fatty acids composition among the three groups. When high dosage of fat is included into a beef cattle diet, the administration of hydrogenated triglycerides, characterized by a pleasant flavour and a small mean particle size, is likely to be more suitable than adding calcium soaps or hydrogenated free fatty acids, probably thanks to its higher DMI and feed conversion rate, respectively. With regard to the latter higher rate, it could be only supposed that it is related to the smaller mean particle size of hydrogenated triglycerides.

INFLUÊNCIA DA ALTA INGESTÃO DE MATÉRIA SECA NA RESPOSTA SUPEROVULATÓRIA EM VACAS MESTIÇAS

This study investigated the effect of high dry matter intake (Flushing) on the superovulatory response of crossbred Nelore x Simmental cows. Fourteen non-lactating cows, with a mean body condition score (BCS) of 4.0 (scale from 1 to 5) were randomly assigned into two groups (Maintenance=M or Flushing=F). Seven days prior to onset of superovulation (SOV) until the last day of treatment with FSH, group F cows were fed a diet to achieve 180% of maintenance. Group M cows were fed a maintenance diet. Seven days after AI, embryos were collected and evaluated. Forty days later, the treatment groups were inverted and another SOV was realized. Variables were compared by paired t test and data are presented as mean ± SEM. The number of recruited (19.6±1.8 and 16.4±2.0) and ovulated (15.0±1.6 and 13.0±1.6) follicles detected by ultrasonography did not differ between the M and F groups, respectively (P>0.10). However, the total number of embryos/ova (14.1±2.3 and 9.5±1.5) and the number of viable embryos (10.1±2.1 and 6.7±1.5) recovered were greater in group M (P KEY WORDS: Bovine, embryo, nutrition, superovulation.

Effect of Feed Additives on Digestibility and Milk Yield of Holstein Cows Fed Wet Brewer Grains

Aguilera-Soto J.I., Ramirez, R.G., Arechiga, C.F., Mendez-Llorente, F., Lopez-Carlos, M.A., Piña-Flores J.A., Medina-Flores C.A., Rodriguez-Frausto, H., Rodriguez-Tenorio, D. and Gutierrez-Bañuelos, H. 2009. Effect of feed additives on digestibility and performance of Holstein cows fed wet brewers grains. J. Appl. Anim. Res. 36: 227–230. To evaluate different feed additives in cows fed wet brewer's grain, 5 ruminal-cannulated Holstein cows (470±45 kg; 18±3 kg d−1 milk), were allotted to a 5x5 Latin-square design. A total-mixed diet containing 33% wet brewers grains (WBG) was provided including: 1) no additives (Control), 2) 1% sodium bicarbonate, 3) 1% sodium bentonite, 4) 33 mg kg−1 sodium monensin and 5) 200 mg kgfibrolityc enzymes. Cows fed bicarbonate or enzymes had significantly higher dry matter intake (DMI). However, apparent digestibility of different nutrients did not differ (P>0.05) among dietary treatments. Similarly except acetate propionate ratio (A:P) none of the ruminal parameters differed among groups. A:P followed the same pattern as DMI. Cows given monensin, enzymes and bicarbonate yielded more milk than control or those given bentonite. Except bentonite all additives increased milk yield.

Effects of feeding cows in early lactation with soy hulls as partial forage replacement on heat production, retained energy and performance

This study measured the effects of replacing corn silage and vetch hay by soy hulls in total mixed rations (TMRs) fed to 25 pairs of cows through 90 d in milk, on dry matter (DM) intake, in vivo digestibility, milk yield and composition, onset of normal estrous activity, body condition score (BCS), health and the energy balance of lactating cows. The partitioning of metabolizable energy (ME) intake between heat production (HP) and retained energy (RE) in milk and body change of each cow was measured. The two TMRs differed in the content of forage and forage aNDFom [235 g/kg versus 350 g/kg; and 128 g/kg versus 187 g/kg DM, in the experimental (EXP) and control (CON) diets, respectively]. This was reflected by an increase in voluntary DM intake by 7.2% ( P=0.02) in the EXP group as compared with the CON. In vivo DM and aNDFom digestibility were 4.9% ( P=0.03) and 22.7% higher ( P=0.01), respectively, in the EXP group than in the CON. The higher DM intake and digestibility of the EXP TMR were reflected by a concomitant increase of 7.4% in milk yield and 10.8% in RE ( P=0.01) of the EXP cows as compared with the CON. The two dietary groups expressed similar somatic cell counts, and metabolic disorders ( i.e., ketosis and/or lameness), as well as pedometer activity (steps/h) suggesting similar udder health, behavior and animal welfare. A trend to an earlier return to normal ovarian activity occurred in the EXP cows as reflected by fewer days to 1st ovulation and advanced outset of estrous cycle. Despite the higher RE of the EXP cows, the HP of both groups was maintained at an upper level of 141–136 MJ/cow/d during the 90 d of the experiment.

Distillers dried grains with solubles compared with rapeseed meal in rations of dairy cows

The aim of the present study was to assess if similar performances of high-yielding dairy cows can be achieved with a high proportion of distillers dried grains with solubles (DDGS) consisting of 90% wheat and 10% barley compared with rapeseed oilmeal (RSM) in the diet. Of a total of 32 dairy cows, 16 were fed RSM as a protein source (16.5% of ration), the others DDGS. Equivalent high dry matter intakes, milk yield, milk fat percentage and milk lactose percentages were observed. Milk protein percentages were lower when DDGS was given. Milk fat, protein and lactose yields nonetheless showed no significant differences when RSM or DDGS were fed. Since similar performances were reached with DDGS and RSM, the tested DDGS can replace RSM as a protein source in the feed of high-yielding dairy cows up to the tested amount of 16.5% of the ration

English

&nbsp; An experiment was carried out to assess the growth performance of African Giant Land Snail&nbsp;Achatina achatina&nbsp;Linnie fed with three natural feedstuff; pawpaw fruit, pawpaw leaves and cabbage leaves. A total of 24 growing snails of approximately one year old were used for the study. These were randomly divided into six groups and then allotted into the three experimental diets, arranged in a completely randomised design (CRD) order. Dry matter intakes of feed being served every other days, weight gain and size increase of snails were assessed fortnightly. The results showed that pawpaw leaf is higher in protein than cabbage leaf and pawpaw fruit. However, cabbage leaf contains some essential mineral elements, which are useful in body building than the other two feedstuffs. It also showed that snails fed with cabbage leaves had the highest dry matter intake and weight gain of 14.2 and 18.6 g, respectively. Highest shell length and circumference increase of 0.3 and 0.6 cm were obtained in pawpaw fruit and pawpaw leaf respectively. Although there was no significance difference (p &gt; 0.05) in the weight gain of snails fed with pawpaw fruit and cabbage leaves, cabbage leaf seems to be richer in protein and other essential mineral elements than pawpaw fruit. It was therefore concluded that cabbage leaf could serve as a good substitute for pawpaw fruit and leaves, which hitherto were known as the preferred natural feedstuff of snails.&nbsp; &nbsp; Key words:&nbsp;African giant land snail, natural feedstuff, protein, mineral elements.

Evaluating estimates of phosphorus maintenance requirement of lactating Holstein cows with different dry matter intakes

The objective was to evaluate estimates of the inevitable fecal loss component of the P maintenance requirement of lactating Holstein cows consuming differing amounts of a low-P diet. The maintenance requirement for P is the sum of inevitable (e.g., unavoidable) endogenous fecal P plus endogenous urinary P when an animal is fed near its true P requirement (i.e., zero P balance). Urinary excretion of P is normally very low in healthy cattle. Inevitable fecal P is the main part of the total P maintenance requirement; it can be expressed as grams of fecal P/kilogram of dry matter intake (DMI). Twenty-one multiparous lactating Holstein cows (55 to 253±6 d in milk, range±SD; 0 to 171±64 d pregnant) with a wide range of pretrial milk yields (25.3 to 47.3±1.23kg/cow per day) were selected to achieve a range in DMI and assigned to treatment groups of low, medium, and high DMI. To obtain an even greater range in DMI, rations fed to cows in the low and medium treatment groups were restricted to 75 and 50% of their pretrial ad libitum intakes, respectively. Dry matter intakes during the experiment averaged 11.3 (low), 15.3 (medium), and 25.1 (high) kg/cow per d, respectively. All cows were fed the same low-P diet (0.26% P, dry basis) throughout the experiment. Phosphorus balances of cows in all treatments were not different from zero and unaffected by DMI. Average daily total inevitable fecal P excretion was 15.3, 18.2, and 26.3 g/cow for low, medium, and high DMI, respectively. Inevitable fecal P excretion was 1.36, 1.19, and 1.04 g/kg of DMI for low, medium, and high and decreased linearly with increasing DMI. The regression equation to estimate inevitable fecal P excretion across the range of DMI was: (g/d)=[0.85±0.070 (g/d)]×DMI (kg/d)+[5.30±1.224 (g/d)]; (R2=0.90). This equation can be used to estimate the inevitable fecal P component of the total P maintenance requirement of lactating Holstein cows.

Grazing behaviour and pattern of intake of dairy cows grazing kikuyu (Pennisetum clandestinum) grass pastures in relation to sward height and length of grazing session

To investigate how grazing time, herbage dry matter intake (DMI) and intake rate (IR) are influenced by intensive grazing management, dairy cows strip-grazing subtropical grass pastures (Pennisetum clandestinum) at two compressed sward heights (10 and 13 cm) and at five grazing durations (1, 2, 4, 8 and 15 h) and replicated over 3 days were studied. The study was conducted in summer and the cows were observed every 20 min from 1600 to 0700 hours to calculate the time spent (min/h) grazing, ruminating and resting. Total time spent grazing was 45 min longer for cows grazing the 13-cm sward than for those grazing the 10-cm sward over the 15-h grazing period. The rate of increase in grazing time was 0.64 h/h grazing duration up to 4 h after introduction to fresh pasture. IR of cows grazing the 13-cm sward was significantly higher than those grazing the 10-cm sward (0.17 v. 0.12 kg DM/min spent grazing). The difference in IRs between sward height treatments resulted from the higher DMI in the 13-cm sward within the first 4 h of grazing compared with the 10-cm sward, although following the first 4-h grazing period IR was similar for both sward heights. Grazing time increased with sward height up to a maximum of 4 h after introduction to fresh pasture and had also maximised herbage DMI by this time. These results have important practical implications for dairy cow grazing management systems because they show that dairy managers could remove cows after 4 h with little compromise in production and will help in developing optimum supplementary feeding strategies when pasture availability limits DMI.

Effect of restricted access time to pasture on dairy cow milk production, grazing behavior, and dry matter intake

The objective of this experiment was to investigate the effect of restricting pasture access time on milk production and composition, body weight and body condition score change, dry matter intake, and grazing behavior of autumn calving dairy cows in midlactation. Fifty-two (19 primiparous and 33 multiparous) Holstein-Friesian dairy cows (mean calving date, August 17±91.2 d) were randomly assigned to a 4-treatment (n = 13) randomized block design grazing study. The 4 grazing treatments were: (i) full-time access to pasture (22H; control), (ii) 9-h access to pasture (9H), (iii) two 4.5-h periods of access to pasture after both milkings (2×4.5H), and (iv) two 3-h periods of access to pasture after both milkings (2×3H). Experimental treatments were imposed from March 7 to April 6, 2007 (31 d). The pregrazing herbage mass of swards offered to all treatments was 1,268kg of dry matter/ha, and sward organic matter digestibility was 86.4%, indicating high-quality swards conducive to high dry matter intake. Swards where animals had 22H and 2×4.5H access to pasture had the lowest postgrazing sward heights (3.5cm), reflecting the greatest levels of sward utilization. After the experimental period, there were no differences in milk production; however, the 2×3H animals tended to have lower milk protein concentration (−0.17%) compared with 22H animals. Furthermore, dry matter intake of the 9H animals was lower than 22H animals. Although restricting access time to pasture decreased grazing time, animals compensated by increasing their intake/minute and intake/bite. Restricting pasture access time resulted in much greater grazing efficiency, because the 9H, 2×4.5H, and 2×3H treatments spent a greater proportion of their time at pasture grazing (81, 81, and 96%, respectively) than 22H animals (42%). Results of this study indicate that allocating animals restricted access to pasture does not significantly affect milk production. This study also found that the total access time should be greater than 6h and that perhaps needs to be divided into 2 periods.

Voluntary intake and diet selection by dairy heifers fed ensiled whole-crop barley and oats harvested at different stages of maturity

This study evaluated feed intake and diet selection of dairy heifers fed whole-crop cereal silage made from oats and six-rowed barley harvested at the heading, early milk and early dough stages, and two-rowed barley harvested at the early milk and early dough stages of maturity. The silages were fed ad libitum to 32 Swedish Red dairy heifers, during three 17-day periods. The oat silage harvested at the early dough stage resulted in a higher dry-matter intake (DMI; 1.92 kg/100 kg live weight (LW)) and a higher organic matter intake (OMI; 1.73 kg/100 kg LW) than the oat silage harvested at the heading stage (DMI = 1.57 kg/100 kg LW; OMI = 1.37 kg/100 kg LW). The DMI, OMI and NDFI of six-rowed barley silage were higher when harvested at the heading stage (2.08, 1.80 and 1.06 kg/100 kg LW) than when harvested at the early milk (1.74, 1.48 and 0.76 kg/100 kg LW) and early dough stages (1.62, 1.46 and 0.70 kg/100 kg LW). The DMI, OMI and NDFI were higher for six-rowed barley than for oat silage harvested at heading, whereas feeding oat silage resulted in a higher NDFI than six-rowed barley silage when harvested at the early dough stage. Reduced intake of barley silage harvested at the early dough stage probably was due to the presence of barbed awns, whilst reduced intake of the early harvested oat silage was most likely due to a low DM content and a high content of fermentation products. When fed oat or two-rowed barley silage harvested at the early dough stage, the heifers selected fractions low in NDF. This indicates that heifers are likely to feed selectively when fed whole-crop cereal silages prepared from crops harvested at the early dough stage.

Ruminal fermentation patterns and parameters of the acid base metabolism in the urine as influenced by the proportion of concentrate in the ration of dairy cows with and without Fusarium toxin-contaminated triticale

Feeding a total mixed ration with 50% concentrate and a mean deoxynivalenol (DON) concentration of 5.3 mg/kg DM to 13 German Holstein cows in early lactation (Myco group) resulted in alterations in the ruminal fermentation patterns (lower molar percentage of acetate and isobutyrate, higher molar percentage of valerate) compared to the 14 control cows (Period 1, 11 weeks). In the Myco group, significantly lower ruminal pH value occurred in weeks 4 and 8 and lower minimum pH values critical for developing subacute ruminal acidosis were detected. Accordingly, the net acid base excretion in the urine and the base-to-acid ratio were lower (significant in week 8 only). These effects probably resulted from a higher dry matter intake and are not related to the presence of Fusarium toxin. In Period 2, the same 27 cows plus five additional cows were divided into four groups over 18 weeks. The effects of an elevated concentrate proportion of 60% were tested with and without Fusarium toxin (Control-60, 0.4 mg DON/kg DM and Myco-60, 4.6 mg DON/kg DM) and compared to two groups fed 30% concentrate (Control-30, 0.6 mg DON/kg DM and Myco-30, 4.4 mg DON/kg DM). As expected, a high concentrate proportion significantly affected the ruminal fermentation patterns. Net acid base excretion and base-to-acid ratio did not reveal a distinct concentrate effect and the ruminal pH values were on a high level in all groups when ruminal fluids were taken after 3–5 hours of feed restriction (median between 6.8 and 7.2). Additional effects were observed on the profile of short chain fatty acids in the presence of Fusarium toxin at both concentrate levels. This indicates a switch in the microbial community due to direct mycotoxin effects and/or indirect effects of the Fusarium infection related alterations in the physico-chemical properties of the infected cereal on ruminal microbes.