DM Cow Research Articles

Evaluation of the Effect of Cow’s Milk Kefir on Serum Tumor Necrosis Factor-alpha (TNF-α) and Expression of Inducible Nitric Oxide Synthase (iNOS) Gene in Liver Rats

TNF-α is a pro-inflammatory cytokine in insulin resistance. Cytokine-induced increase in TNF-α production by the iNOS pathway plays an important role in diabetes. This study was designed to determine the effect of cow's milk kefir as an antidiabetic and expression of the iNOS gene. Twenty-five Wistar rats were divided into 5 groups. Group cow’s milk kefir dose variation (50%, 75%, and 100%). This study showed that TNF-α levels in the DM control rat group were higher compared to other DM rat groups that were given cow’s milk kefir treatment. The cow's milk kefir treatment group (50%) had a higher average TNF-α content (146.3± 6.68) compared to the other two treatment groups given 75% cow's milk kefir (169.9± 6.39) and 100% cow's milk kefir (175.3± 4.66). There were differences in TNF-α levels between treatment groups (p=0.0013). The expression of the iNOS gene in the healthy control group was highest found in the M rat groupgiven 50% milk kefir and the lowest in the DM rat group given 100% milk kefir. There weresignificant differences in iNOS gene expression between groups (p = 0.0019). There was a significant difference between the DM rat group that was treated in the form of 50% group with DM Rats (positive controls) (p= 0.0048) and DM cow’s milk Kefir rats 75% milk with DM Rats (Positive controls) (p=0.0128). This study shows that there is an effect of cow's milk kefir as an antidiabetic on TNF-α and iNOS gene expression.

Secondary growth rye or triticale silage: Small-grain cereals as a dual-purpose forage option for small-scale dairy systems in the highlands of Mexico

Small-grain cereals may be a forage alternative for small-scale dairy systems under limiting climatic conditions given their short agronomic cycle. Cereals as dual-purpose forages (grazing and silage) have not been evaluated in Mexico. The objective was to assess the inclusion of rye (Secale cereale L.) (SCS) or triticale (×Triticosecale spp.) silage (TRS). The treatments were: T1 = 10 kg DM cow-1 d-1 SCS, T2 = 10 kg DM TRS, in both treatments with grazing access (8 h d-1) of a Kikuyu grass (Cenchrus clandestinus (Hochst. ex Chiov.) Morrone) pasture and supplemented with 3.6 kg DM cow-1 d-1 concentrate; in a double cross-over with six cows and three 14 d experimental periods, animal (milk yield, live weight, body condition score, and sampling for milk composition) and feed variables (net herbage accumulation, sward height and sampling for chemical composition) were recorded during the last 4 d of each period. There were no differences (P > 0.05) between treatments for milk yield (13.3 ± 2.8 kg cow-1 d-1), live weight (512.1 ± 85.9 kg), body condition score (2.2 ± 0.2), milk fat (35.8 ± 5.2 g kg-1), milk protein (27.8 ± 0.6 g kg-1), milk urea N (9.8 ± 2.5 mg dL-1) or milk pH (6.8 ± 0.07). Feeding costs were lower in SCS (P < 0.05); which may be an alternative for small-scale dairy systems. It is concluded that both rye and triticale are good alternatives as dual-purpose forage crops.

The effects of herbage allowance on pasture characteristics and milk production of dairy cows

ABSTRACTThis study aimed to evaluate the effect of herbage allowance on forage productivity, botanical composition and milk yield of Holstein cows. The treatments comprised three conditions of pasture allowance, high (38.4 kg DM cow−1 day−1), medium (30.3 kg DM cow−1 day−1) and low (26.8 kg DM cow−1 day−1) forage supply during autumn, and throughout the pasture allowance conditions of high (49.8 kg DM cow−1 day−1), medium (33.7 kg DM cow−1 day−1) and low (27.6 kg DM cow−1 day−1) herbage supply during spring. Significant differences (P < .05) were observed for forage accumulation, total biomass production and animal stocking rate according to the seasons. Herbage allowance affected (P < .05) the botanical composition and milk production, registering a decrease in Festuca in the summer, and a continuous reduction in legume proportion. Pasture management with a medium herbage allowance throughout the year provided a greater total annual milk production per hectare.

Oat silage for grazing dairy cows in small-scale dairy systems in the highlands of central Mexico

The objective was to evaluate the provision of oat silage (Avena sativa) to supplement grazing dairy cows on pastures of perennial ryegrass (Lolium perenne), festulolium (Lolium multiflorum × Festuca pratense) and white clover (Trifolium repens) during the dry season when pasture growth is limited. The experimental design was a 3 × 3 Latin square replicated three times, with nine milking Holstein cows (mean live weight 496.2 ± 33.6 kg and daily milk yield 14.8 ± 2.8 kg cow−1) under on-farm participatory rural research. Experimental periods were 14 d. Simulated grazing samples of pasture herbage were analysed for chemical composition, sward height recorded and net herbage accumulation determined from exclusion cages. Treatments were the inclusion of oat silage at T0 = 0 kg DM cow−1 d−1 of oat silage, T3 = 3 kg DM cow−1 d−1 of oat silage, and T6 = 6 kg DM cow−1 d−1 of oat silage, plus 5.0 kg fresh weight commercial concentrate and 9 h of continuous grazing. Animal variables were milk yield and composition, live weight and body condition score. Feeding costs were calculated. Mean milk yield was 18.9 ± 0.27 kg cow−1 d−1 with no differences in animal variables (p > 0.05), but feeding costs per kilogram milk increased 25% for T3 and 50% for T6. Oat silage supplementation is only viable under difficult grazing conditions.

Effect of daily herbage allowance restriction on pasture characteristics and milk production by grazing dairy cows in spring

The cumulative effects of daily herbage allowance (DHA) restriction on pasture characteristics and the sustainability of pasture-based dairy systems were evaluated. Sixty-four dairy cows were randomly assigned to one of two grazing treatments (20 and 30 kg DM cow-1 day-1). Milk yield and pre- and post-grazing herbage mass were recorded for every grazing event. Botanical and chemical compositions of the pasture were evaluated. Low DHA increased the stocking rate by 0.7 cows ha-1 and consequently increased grazing efficiency from 41 to 47%. Daily herbage allowance restriction did not affect pasture characteristics or milk production per cow, but DHA restriction increased milk production per hectare (+27%). The results suggest that restriction on daily herbage allowance ensures a higher level of herbage utilization and milk output per ha than high DHA, without affecting pasture characteristics. Therefore, DHA might be a useful grazing management tool for improving the profitability and sustainability of grazing-based dairy systems.

External validation of the GrazeIn model of pasture dry matter intake and milk yield prediction for cows managed at different calving dates and stocking rates

The aim was to evaluate the prediction accuracy of pasture dry matter intake (PDMI) and milk yield (MY) predicted by the GrazeIn model using a database representing 124 PDMI measurements at paddock level and 2232 MY measurements at cow level. External validation of the model was conducted using data collected from a trial carried out with Holstein-Friesian cows (n=72) while grazed 28 paddocks and were managed in a 2×2 factorial design by considering two calving dates (CD), with different number of days in milk (DIM), early (E, 29 DIM) vs. middle (M, 167 DIM), and two stocking rates (SR), medium (M, 3.9 cows ha-1) vs. high (H, 4.8 cows ha-1), under a rotational grazing system. Cows were randomly assigned to four grazing scenarios (EM, EH, MM and MH). The mean observed PDMI of the total database was 14.2 kg DM cow-1 day-1 while GrazeIn predicted a mean PDMI for the database of 13.8 kg DM cow-1 day-1. The mean bias was −0.4 kg DM cow-1 day-1. GrazeIn predicted PDMI for the total database with a relative prediction error (RPE) of 10.0% at paddock level. The mean observed MY of the database was 23.2 kg cow-1 day-1 while GrazeIn predicted a MY for the database of 23.1 kg cow-1 day-1. The mean bias was –0.1 kg cow-1 day-1. GrazeIn predicted MY for the total database with a mean RPE of 17.3% at cow level. For the scenarios investigated, GrazeIn predicted PDMI and MY with a low level of error which made it a suitable tool for decision support systems.

Milk production, grazing behavior and nutritional status of dairy cows grazing two herbage allowances during winter

Winter grazing provides a useful means for increasing the proportion of grazed herbage in the annual diet of dairy cows. This season is characterized by low herbage growth rate, low herbage allowance, and low herbage intake and hence greater needs for supplements to supply the requirements of lactating dairy cows. The aim of this study was to determine the influence of herbage allowance (HA) offered to autumn calving dairy cows grazing winter herbage on milk production, nutritional status, and grazing behavior. The study took 63 d using 32 multiparous Holstein-Friesian dairy cows. Prior to experimental treatment, milk production averaged 20.2 ± 1.7 kg d -1 , body weight was 503 ± 19 kg, and days in milking were 103 ± 6. Experimental animals were randomly assigned to two treatments according to HA offered above ground level: low (17 kg DM cow -1 d -1 ) vs. high HA (25 kg DM cow -1 d -1 ). All cows were supplemented with grass silage supplying daily 6.25 and 4.6 kg DM of concentrate (concentrate commercial plus high corn moisture). Decreasing HA influenced positively milk production (+25%), milk protein (+20 kg), and milk fat (+17 kg) per hectare; however no effects on milk production per cow or energy metabolic status were observed in the cows. In conclusion, a low HA showed to be the most significant influencing factor on milk and milk solids production per hectare in dairy cows grazing restricted winter and supplemented with grass silage and concentrate; but no effect on the milk production per cow was found.

Fatty acid intake and rumen fatty acid composition is affected by pre-grazing herbage mass and daily herbage allowance in Holstein dairy cows

The objective of this study was to investigate the effect of level of pre-grazing herbage mass (HM) and daily herbage allowance (DHA) on the fatty acid (FA) intake and composition of ruminal content of grazing dairy cows. Four rumen fistulated Holstein-Friesian dairy cows were allocated to either a high or low HM (1700 vs 2600 kg DM ha-1) and within herbage mass treatment further allocated to a high or low DHA (20 vs 16 kg of DM cow-1 day-1) in a 4 × 4 Latin square design. Total FA intake and linolenic acid (LNA) intake was higher for cows on high DHA (p&lt;0.05). Ruminal oleic acid, linoleic and LNA were not affected by treatments. Ruminal stearic acid (C18:0) and vaccenic acid (VA) concentrations were higher at low HM (43.6 and 14.8 g/100 gof FA respectively; p&lt;0.01) compared to high HM (42.0 and 12.5 g/100 gof FA respectively for C18:0 and VA). Cows grazing high DHA had higher ruminal concentration of VA (15.3 g/100 gof FA; p&lt;0.01) than low DHA (12.1 g/100 gof FA). Regarding milk FA composition, only some of the milk FA varied across treatments, being the VA and LNA concentrations higher at low HM (p&lt;0.05). These data suggest that low HM and high DHA, at least within the range studied here, promotes the accumulation of ruminal VA which could be available for subsequent conversion within the mammary gland to the human health promoting c9,t11 isomer of conjugated linoleic acid.

Productive and metabolic response to two levels of corn silage supplementation in grazing dairy cows in early lactation during autumn

Corn (Zea mays L.) silage (CS) is a nutritious food that can be used as a supplement in dairy cows. The aim of this study was to determine the effect of supplementation with two amounts of CS on milk production and composition, live weight and body condition, as well as on some blood indicators for energy and protein metabolism on dairy cows in early lactation and grazing low mass pasture during autumn. The study was carried out in 40 Holstein Friesian cows over 57 d. Prior to experimental treatment, milk production and days of lactation averaged 24.1 ± 2.8 kg d-1 and 62 ± 14 d, respectively. The dietary treatments consisted of two levels of supplementation with CS; 4.5 and 9 kg DM cow-1 d-1 (treatments LCS and HCS, respectively). Additionally, all the cows received a pasture allowance of 21 and 3 kg DM cow-1 d-1 of concentrate. Milk composition was determined using infrared spectrophotometry, while blood indicators were obtained using an autoanalyzer. There were not differences between treatments regarding milk production or composition, total DM or energy intake. Herbage and protein intake was higher for LCS treatment (P < 0.001). Increasing supplementation decreased (P < 0.001) daily weight gain but did not affect body condition. Plasma concentrations of βOH-butyrate were lower (P = 0.038) for the LCS treatment; while urea concentrations were higher (P = 0.003), with no differences for non-esterified fatty acids (NEFA) concentrations. Supplementation with 4.5 kg d-1 of CS was sufficient to meet the production requirements of the cows.

Effect of grazing management on herbage protein concentration, milk production and nitrogen excretion of dairy cows in mid‐lactation

AbstractThe objective of this experiment was to use diurnal and temporal changes in herbage composition to create two pasture diets with contrasting ratios of water‐soluble carbohydrate (WSC) and crude protein (CP) and compare milk production and nitrogen‐use efficiency (NUE) of dairy cows. A grazing experiment using thirty‐six mid‐lactation Friesian x Jersey cows was conducted in late spring in Canterbury, New Zealand. Cows were offered mixed perennial ryegrass and white clover pastures either in the morning after a short 19‐day regrowth interval (SR AM) or in the afternoon after a long 35‐day regrowth interval (LR PM). Pasture treatments resulted in lower pasture mass and greater herbage CP concentration (187 vs. 171 g kg−1 DM) in the SR AM compared with the LR PM but did not affect WSC (169 g kg−1 DM) or the ratio of WSC/CP (1·0 g g−1). Cows had similar apparent DM (17·5 kg DM cow−1 d−1) and N (501 g N cow−1 d−1) intake for both treatments. Compared with SR AM cows, LR PM cows had lower milk (18·5 vs. 21·2 kg cow−1 d−1), milk protein (0·69 vs. 0·81 kg cow−1 d−1) and milk solids (1·72 and 1·89 kg cow−1 d−1) yield. Urinary N concentration was increased in SR AM, but estimated N excretion and NUE for milk were similar for both treatments. Further studies are required to determine the effect of feeding times on diurnal variation in urine volume and N concentration under grazing to predict urination events with highest leaching risk.

Effect of pasture allowance and cows’ lactation stage on perennial ryegrass sward quality, pasture dry matter intake and milk performance of Holstein-Friesian cows

Efficient exploitation of grass for cattle requires the application of appropriated grassland management strategies to maximize pasture dry matter intake (PDMI) while maintaining high sward quality by allocating cows to an adequate pasture allowance (PA). The aim of this study was to investigate the effect of two PA, low (L) vs. high (H), on sward quality, PDMI and milk performance of Holstein-Friesian cows (n=72) at two lactation stages (LS), early (E) vs. middle (M). Cows were randomly assigned to four groups (LE, LM, HE and HM) in a 2×2 factorial design. The low PA treatments completed 5 rotations, with more grazing days (+13), lower pre- (14.3) and post-grazing (5.3) sward heights (cm) and higher herbage utilization (81.7%). The low PA had higher stocking rate than the high PA treatments (4.8 vs. 3.9 cows ha-1)and lower PDMI (13.4 kg vs. 14.4 DM cow-1 day-1) with higher (p&lt;0.05) (g kg-1 DM) protein (149.1), carbohydrates (166.7) and digestibility (746.8) while lower (p&lt;0.05) DM (18.4%), acid (283.5) and neutral detergent (508.6) fibers (g kg-1 DM). Sward quality is deteriorated (p&lt;0.05) from rotation 1 to 5, lower decrease was found on low PA treatments. Milk yield (MY) was higher (p&lt;0.05) in cows at early LS (24.8 kg cow-1 day-1), with the lowest (p&lt;0.05) protein (28.9) and fat (36.9) content (g kg-1). No differences were found on MY between PA treatments, but higher protein and fat content were observed on low PA. Decreasing PA resulted in higher sward and milk quality without penalizing MY.

Relationship between diurnal grazing time and herbage intake in dairy cows in rotational grazing

The aim of this study was describe the relationship between grazing time and herbage intake and identify tools to grazing management of dairy cows grazing Italian ryegrass (Lolium multiflorum Lam.) on a rotational grazing method. Six dairy cows in mid-lactation period were allowed to graze paddocks during three grazing cycles. During each cycle cows grazed two paddocks with 9 days of occupation by paddock and an herbage allowance of 30kg DM cow-1 day-1. Measurements were made in the last 9 days of each period and during intervals between cycles cows grazed an adjacent area with a mixed of temperate species. It was compared three grazing cycles and cows eating similar herbage amount with different daily grazing time. Independently of herbage intake, daily grazing time increased 12min by cm of the reduction on leaf height. Reductions on efficiency to graze are clearly associated to structural traits of canopy as proximity to ground level and stems + pseudo-stems content on the graze layer. In conclusion, under rotational grazing, daily grazing time is strongly associated with leaf height in the grazing layer, but it is not a good indicator of DM herbage intake. Structural traits of canopy are clearly associated with efficiency to graze, independently of daily herbage intake.

Farelo de glúten de milho para vacas leiteiras em pastos de azevém anual

Neste trabalho, foi avaliado o efeito da suplementação com proteína de baixa degradabilidade ruminal (PNDR) para vacas leiteiras em pastos de azevém anual (Lolium multiflorum Lam.). Foram utilizadas 12 vacas da raça Holandesa no terço médio de lactação. Os tratamentos avaliados foram zero e 4,0kg vaca-1 dia-1 de uma mistura 60:40 de grão de milho + farelo de glúten de milho, em três períodos de avaliação de 15 dias. Os animais foram distribuídos em quatro lotes uniformes (dois por tratamento) e alocados em piquetes de azevém manejado no método rotativo, com uma oferta de 24kg de MS vaca-1 dia-1. A massa de forragem (2.325kg MS ha-1) e a altura (15,8cm) antes da entrada dos animais foram semelhantes nos piquetes dos animais suplementados e não suplementados. Da mesma forma, os teores médios de PB e FDN da forragem ingerida foram semelhantes entre tratamentos (18,9% e 53,0%, respectivamente). O consumo de MS da forragem não variou com o uso da suplementação (média=8,5kg vaca-1 dia-1). O consumo de MS total aumentou 3,0kg vaca-1 dia-1 e o de energia metabolizável aumentou 42MJ vaca-1 dia-1. A produção de leite aumentou 4,0kg vaca-1 dia-1 com o uso da suplementação, mas os teores de gordura e de proteína não variaram entre tratamentos, sendo observados valores médios de 32,8g kg-1 e 29,2g kg-1, respectivamente. Em baixa oferta de forragem, a suplementação com alimento concentrado (22% PB) contendo farelo de glúten de milho eleva a produção de leite na ordem de 1kg por kg de concentrado. A resposta a esse tipo de suplementação em condição de oferta de forragem não-limitante deve ser estudada.

Dairy cow performance on silage from semi-natural grassland

The effects of including forage from semi-natural grassland in the diet of dairy cows were studied in a feeding trial with cows in mid-lactation. Diets were compared in which part of the silage from intensively managed grassland was replaced with 0% (100IM), 20% (20SPP), 40% (40SPP) or 60% (60SPP) silage from species-poor semi-natural grassland or with 60% silage from species-rich semi-natural grassland (60SPR). On a dry matter basis, the total mixed ration (TMR) contained 63% grass silage, 18% maize silage and 19% concentrates. Concentrates were either low or high in protein to prevent protein surpluses or shortages. High producing cows were offered additional concentrates in concentrate boxes. The additional concentrates had the same composition as the concentrates in the TMR. With the 60SPP diet voluntary daily intake decreased by 1.4 kg DM cow −1 day −1. Uncorrected milk production was the same for all diets, but milk fat yield was lower with the 60SPP diet and milk protein yield lower with the 60SPR diet than with the other diets. No statistically significant differences in fat and protein corrected milk production were observed between the 100IM and the 20SPP diet. The fat and protein corrected milk production with the other diets was significantly lower than with 100IM. All cows gained body weight, but there were no statistically significant differences between diets. In conclusion, if used in low quantities (< 40%], silage from semi-natural grassland can be included in the diet of lactating dairy cows without reducing production. This conclusion is based on the presented results and cannot be generalized.

Effects of grass pasture and concentrate‐based feeding systems for spring‐calving dairy cows in early spring on performance during lactation

AbstractThe effect of offering a total mixed ration of silage and concentrate (proportionately 0·44 silage) system [indoor feeding system (IF)] was compared with grazing at a high daily herbage allowance with a low level of concentrate supplementation [early grazing system (EG)] in early spring on the performance of spring‐calving dairy cows in Ireland. Sixty‐four spring‐calving Holstein–Friesian dairy cows (mean calving date, 2 February) were allocated to one of two systems between 16 February and 4 April 2004. An equal number of primiparous and multiparous cows were assigned to each system. The dairy cows on the IF system were housed for a 7‐week period and offered a diet of 10·9 kg DM cow−1 d−1 (s.d. 2·3) of concentrate, the remainder of the diet was 8·6 kg DM cow−1 d−1 (s.d. 1·9) of grass silage. The dairy cows on the EG system were offered a mean daily herbage allowance of 15·1 kg DM cow−1 d−1 (s.d. 3·7) and were supplemented with 3·0 kg DM cow−1 d−1 (s.d. 1·0) of concentrate. There was no difference in milk yield between the two systems but the cows in the EG system had a higher milk protein concentration (2·9 g kg−1) and a higher milk protein yield than in the IF system. Milk fat concentration was higher for cows in the IF than EG system (3·0 g kg−1). There was no difference in total daily dry‐matter intake between the systems, measured in week 6 of the study. Mean live weight of the cows in the IF system was greater than in the EG system. The results of the study suggest that a slightly greater performance can be achieved by a system offering a high daily herbage allowance to spring‐calving dairy cows in early lactation compared with a system offering a total mixed ration containing a high proportion of concentrate with grass silage.

Defoliation pattern, foraging behaviour and diet selection by lactating dairy cows in response to sward height and herbage allowance of a ryegrass‐dominated pasture

AbstractThe effects of sward surface height (SSH) and daily herbage allowance (HA) on the defoliation pattern and grazing mechanics of early lactation dairy cows grazing on irrigated perennial ryegrass–white clover pasture were studied. The hypothesis tested was that SSH and HA affect intake and diet selection through their effects on the pattern of defoliation which is influenced by the resistance to prehension bites.Factorial combinations of two initial SSH (14 and 28 cm) and two daily HA (35 and 70 kg DM cow−1 d−1) were examined in a replicated experiment. The peak longitudinal tensile force required to break the sward portion encompassed in a 100 cm2 area [bite fracture force (BFF100)] was measured as an index of the resistance to prehension.The volume of herbage defoliated and herbage intake increased with SSH (P &lt; 0·05) and HA (P &lt; 0·01). Corresponding to an increase in HA from 35 to 70 kg DM cow−1 d−1, there was a proportional increase in the total defoliation area (TDA) and intake by 0·24 and 0·55 in the short sward compared with 0·16 and 0·32 in the tall sward respectively. The results of this experiment suggest that a consistent spatial pattern of reduction of the canopy exists during defoliation by cows and that the volume of sward canopy defoliated is the major variable affecting herbage intake.The BFF increased down the sward profile at a rate that was higher (P &lt; 0·05) for the taller sward than for the shorter sward. It is proposed that a relatively lower resistance to prehension in the short sward compared with the tall sward explains the greater proportionate increase in TDA and intake corresponding to an increase in HA. The rate at which BFF100 increases down the sward profile is suggested as a sward physical variable that can influence the defoliation process. The estimated time and energy costs of prehension bites are discussed in the context that larger bites are handled more efficiently than smaller bites.

Hydrogenated fish fat for grazing dairy cows in summer.

Thirty-two multiparous Holando argentino cows in mid lactation were randomly assigned to two treatments: control or HFF (hydrogenated fish fat) at Rafaela, 31 degrees 11' South, during summer 1997/1998, to evaluate the effect of using HFF as a supplement under grazing conditions. Animals in both treatments grazed an alfalfa pasture, and were confined from 1000 hours to 1700 hours daily in a shaded pen where water was provided ad libitum. During each milking, animals in the control group received 3.73 kg dry matter per cow each day (DM cow(-1) day(-1)) concentrate (15% crude protein; 8.69 MJ energy for location/kg DM). Cows in the HFF group received 3.25 kg DM cow(-1) day(-1) concentrate, plus 0.200 kg DM cow(-1) day(-1) HFF. Both diets presented similar energy, protein and neutral detergent fibre contents. The trial was performed during a strong "El Niño" event, which resulted in a total rainfall of 396.3 mm (80% higher than normal). The mean temperature was 23.7 (SD 3.2) degrees C and the mean temperature humidity index was 72.9 (SD 4.96). Production data were analysed using a completely randomised design with analysis of covariance. Supplementation with HFF produced an increase in daily milk production (26.4 (SD 2.46) l/cow compared to 23.9 (SD 2.68) l/cow for the controls; P<0.05). Milk fat production was higher for HFF (P<0.05): 941 (SD 96) g cow(-1) day(-1) as compared to controls, which yielded 846 (SD 95) g cow(-1) day(-1). Milk protein yields also differed significantly (P<0.05), the respective values for HFF and controls being 795 (SD 72) g cow(-1) day(-1) and 715 (SD 83) g cow(-1) day(-1). It was concluded that hydrogenated fish fat could be a good ingredient to sustain high yields and elevated maintenance requirements in a grazing system during hot conditions.

Feed intake and performance of dairy cows during feeding of fodder beets supplementing grass silage

In a feeding experiment 3 x 12 dairy cows (German Simmental x Red Holstein Friesian) were used to investigate the influence of different amounts of fodder beets on feed intake, milk yield and milk composition. The fodder beets (variety Kyros) were fed in exchange for concentrate. The amounts of fodder beets were either 22 kg cow-1 d-1 or 44 kg cow-1 d-1 or zero (control group). All groups received 4 kg hay cow-1 d-1, grass silage ad libitum, and concentrate corresponding to the milk yield. In order to balance the rations the concentrate was either rich in protein or rich in energy. Feeding 22 kg or 44 kg fodder beets increased forage intake (including fodder beets) significantly. However, the total feed intake diminished on average from 18.3 kg DM cow-1 d-1 (control group) to 17.2 kg DM cow-1 d-1 (fodder beet groups). In each treatment the intake of hay was 3.3 kg DM cow-1 d-1. However, the intake of grass silage offered ad libitum was significantly suppressed by the fodder beets. Considering the different amounts of concentrate the quantity of suppression of grass silage by feeding fodder beets was calculated at -0.8 kg DM of grass silage per kg DM of fodder beet intake. The milk yield decreased linearly with increasing fodder beets on average up to 4 kg cow-1 d-1. However, the milk composition was scarcely influenced. The fat content increased a little, the mean alterations of the protein and lactose content were below 0.1 percentage points. Therefore, the change in daily excretion of milk fat, protein or lactose were similar to the change in milk yield. In conclusion, feeding fodder beets in combination to grass silage causes a positive effect on forage intake (including fodder beets). However, the amount of concentrate should not be reduced equivalently to the energy contents of the added fodder beets.

Some effects of herbage composition, as influenced by previous grazing management, on milk production by cows grazing on ryegrass/white clover pastures. 1. Milk production in early spring: effects of different regrowth intervals during the preceding winter period

AbstractTwo experiments (1a and 1b) were carried out to examine the effects of differences in pre‐grazing herbage mass and composition on milk production by cows grazing in early spring. Swards with high (5 · 1t DM ha−1) or low (2 · 9 t DM ha‐1) pre‐grazing masses in early spring were created by either long or short periods of regrowth during the preceding winter.The low‐mass swards contained lower concentrations of grass stem and senescent material, but higher concentrations of clover, than the high‐mass swards. Herbage from the low‐mass swards was also more digestible.Cows were offered common daily herbage allowances from both swards (26 and 22 kg DM cow−1 in Experiments la and lb respectively). The cows grazing on the low‐mass swards produced significantly greater yields of milk, milk fat and milk protein.The results show that herbage from the lowmass swards was of higher feeding value for lactating cows in early lactation. The practical implications for milk production per cow and per hectare are discussed.

Maize silage for the pasture-fed dairy cow. 4. A comparison between grazed annual pastures and feedlotting in the winter

Dairy cows in early lactation grazed irrigated annual pastures during 14 weeks in autumn and winter. They were grazed for either 2 or 6 h each day and then restricted to a feedpad and offered ad libitum maize silage. Other cows were fed 1 of 2 diets while in yards: a feedlot diet based on cereal grain, maize silage, and protein supplement; a mixture of conserved legume and maize silage. Feed intakes and cow performance were monitored. Cows in metabolism cages were fed the feedlot diet with various combinations of red clover and maize silage. Digestibility and rate of disappearance of test feeds from nylon bags were measured in the metabolism trials. Rumen samples were analysed for pH, ammonia, and volatile fatty acids. Dietary constituents were evaluated in vitro and in vivo using sheep. The cows on the feedlot diet recorded the highest DM intakes and the highest liveweight gain, and initially produced the most milk and milk protein. Their milk yields eventually fell to levels similar to those of the grazing cows. Cow performance was poorest on the pasture silage-maize silage mixture, and this treatment was discontinued after only 8 weeks. The poor performance was partly attributed to reduced silage quality from heat damage during ensiling the pasture. Supplementing red clover with increasing levels of maize silage did not influence digestibility but reduced DM intakes and cow performance. Cows grazing for 2 h/day produced 1-2 L/day less milk, and lost more weight, than cows grazing for 6 h/day; their rumen ammonia fell below critical levels. The grazing of high-clover pastures between morning and afternoon milking, combined with maize silage supplementation, is convenient and sustains high milk yields during early lactation.