High-yielding Cows Research Articles

AUTOMATION IN DAIRYING: NEW DEVELOPMENTS

The development of systems for the detection and monitoring of sick cows and cows in oestrus are important features for improving the farm management. Sensors are available now for the in-line detection of mastitis and cows in oestrus. The in-line monitoring of milk quality and milk composition allows the farmer to optimize the individual feeding of high-yielding cows and to separate milk with a certain protein content. In-line measuring of the fat and protein contents can replace the time-consuming sampling done by the milk recording organizations. Equipment for automatically attaching milking units has been developed in various countries. In the Netherlands, IMAG-DLO has been conducting experiments on its experimental farm since 1990, to investigate the potential of a fully automated milking system. These experiments have ascertained the technical performance of the system, the efficacy of a selection unit for controlling the cow traffic, the impact of the selection units and AMS on cow behaviour and welfare, as well as the effects of more frequent milking on milk production and milk composition. Three Dutch firms have developed automatic milking systes and two (Prolion and Lely) have currently about 30 installations actually working on farms. In England, France and Germany similar sytems are being tested under laboratory conditions.

An Evaluation of Zero-Grazing Under a Napier Grass-Based System in High-Yielding Cows at Small-Holder Level

An Evaluation of Zero-Grazing Under a Napier Grass-Based System in High-Yielding Cows at Small-Holder Level

Group 2. Food intake constraints in the high-yielding cow

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Nutrient balance in the diet of grazing dairy cows

A method is described for estimating the nutrient content of pasture selected by grazing cows. The method is non-invasive and suitable for use on commercial farms. Results from use of the method are reported for studies on a commercial farm over a period of 29 months. Confidence limits were calculated for estimated nutrient contents of pasture eaten. Estimated nutrient contents then were compared with recommended nutrient contents for high-yielding cows. Significant deficiencies of energy, protein, Ca, P and Na were common. Seasonal trends in nutrient content of pasture eaten are reported, together with selection differentials between pasture eaten and pasture available.

Fatty Acids, Calcium Soaps of Fatty Acids, and Cottonseeds Fed to High Yielding Cows

We examined the effects of dietary fat as cottonseed, fatty acids, or calcium soaps of fatty acids in the rations of high yielding lactating cows receiving low forage. Experiments were with isoenergetic, isonitrogenous diets containing equal amounts of forage. Inclusion of up to 510 g/d of fatty acids in the ration enhanced FCM yield. With cottonseed, increased FCM was mainly due to increased fat yield. Dietary fatty acids tended to increase milk in mid and late lactation and to decrease fat percentage. Calcium soaps of fatty acids enhanced FCM, particularly in early lactation. Feeding cottonseed and fatty acids together did not enhance yield. Effects described may be attributed in part to changes in ruminal fermentation in which cottonseed increased acetate concentrations and fatty acids decreased the ratio of acetate and butyrate to propionate and in part to enhanced efficiency of milk yield when fat was included in the ration.

Portal-drained viscera (PDV) and hepatic balance of energy metabolites in high-yielding cows. Effects of a fat supplement on PDV rates

Portal-drained viscera (PDV) and hepatic balance of energy metabolites in high-yielding cows. Effects of a fat supplement on PDV rates

Effect of milk production on reproductive performance in the high producing and BST supplemented dairy cow

Higher-yielding dairy cows have reduced reproductive efficiency compared lower-yielding herdmates. This relationship is likely to be seen whether increased production is achieved through superior genetics or somatotropin (GH) supplementation. Increased days open in the high-yielding cow are most probably related to a slight delay in return of cyclic ovarian activity and reduced 1st service conception rates. Reduced fertility in the high-yielding cow is not directly related to increased milk yield but rather to loss of body wt and body condition. The magnitude of the negative impact of milk production on reproduction depends on the cumulative negative energy balance in early lactation. High-yielding cows can achieve optimal reproductive efficiency if they are given adequate energy and protein to support high levels of milk production in early lactation, and replenish adequate body condition in late lactation and the dry period. While GH-supplemented cows are similar to higher-yielding, genetically superior cows in that total milk is increased for the lactation, they may differ in the patterns of milk production over the lactation. Depending on the time of initiation of GH supplementation and the duration of administration, the GH-supplemented cow may have a greater persistency of the lactation curve. Subsequently, the GH-supplemented cow will produce a higher percentage of total milk in the latter part of lactation, changing the rate of profit accumulation. With more milk being produced in late lactation, the importance of maintaining a minimal calving interval may be reduced. The voluntary waiting period prior to mating may be intentionally extended, thereby reducing the pressures of early post-partum remating, when 1st service conception rates are often low in high-yielding cows. Maintaining profitable levels of milk production for longer lactation cycles will allow for later post-partum mating and reduce culling for reproductive failure. Reduced calvings per yr may actually extend herd life by reducing the number of disorders associated with the early post-partum period.

Simplified rotational grazing management of dairy cows: effects of rates of stocking and concentrate

SUMMARYAn experiment was carried out in Normandy between 1986 and 1988 over c. 6 months in each year, using a simplified rotational grazing technique (two paddocks in spring, four in autumn) with a total of 162 high-yielding cows (mean milk yield of 30·0 kg/day at turn-out). Three stocking rates, designated control (C: 2·3 cows/ha over the total area of the system), moderate (M: 2·6 cows/ha = 115% of C) and high (H: 3·0 cows/ha = 130% of C), were compared at two rates of concentrate supplement, 3·7 kg/cow per day and 0·5 kg/cow per day. Individual milk yield differed by a non-significant 5% between the extreme stocking rates (21·3 v. 20·3 kg fat-corrected milk (FCM) for treatments C and H, respectively). Milk production/ha was 23% greater in the H treatment (9816 v. 7970 kg FCM for H and C, respectively). Concentrate supplementation led, on average, to a 9% milk yield improvement (21·8 v. 20·0 kg FCM for high and low rates, respectively), i.e. a mean efficiency of 0·6 kg FCM/kg supplement. This response tended to be greater in the higher-yielding cows and for the high stocking rate. The sward measurements contributed to a better understanding of herbage utilization by the cows.

乳牛における分娩前後のエネルギー水準が肝臓の脂肪沈着, 血液成分および乳蛋白率に及ぼす影響

Two experiments were conducted to investigate the effect of dietary energy intake before and after parturition on fatty infiltration in the liver, blood composition and milk protein in cows. In the dry period, ten cows received a diet with 130% of normal energy requirement (experiment 1), while eight cows received a diet with 80% of required energy (experiment 2). At 16 weeks postpartum, the cows were divided into two groups by their level of energy intake, that is 80% and 100% in experiments 1 and 2, respectively. In the experiment 1, cows with an 80% postpartum feeding had average 18% of fatty infiltration in liver cells at 2-week postpartum, while high-yielding cows had more than 40% fat in the liver for a month. However, fatty infiltration was hardly observed in cows fed at the 100% feeding level. In the experiment 2, the ratio of fatty infiltration averaged 12% for cows at 80% feeding level, and 10% for cows at 100%. Cows with more than 20% of fatty infiltration retained over 14% of the pigments after 30 min by the bromusulphalein test, thus showing a depressed liver function. These indicate that extensive mobilization of fatty acid during early lactation may be the prime cause for fatty liver, while overfeeding during the dry period may not result in fatty liver under appropriate feeding conditions after parturition.

Effects of pattern of concentrate feeding on milk production of dairy cows offered silage ad libitum.

In three 24-wk experiments beginning at wk 4 post partum, a system of concentrate feeding at a flat level was compared with feeding concentrates to milk yield (experiments 1 and 2), or with a high-low 2-step system in which the rate was reduced after wk 12 (experiment 3). Roughage was offered ad lib. In experiment 1 two types of concentrates were involved whereas in experiment 3 two levels of concentrates were applied. The systems were evaluated using high levels of concentrates and with Friesian and Holstein-Friesian cows producing about 7000 kg milk/lactation. Experiments 1 and 3 involved 64 and experiment 2 32 cows. In the comparison between feeding strategies, differences in yield and composition of milk were of minor importance except for milk protein content on the moderate-quality grass silage diet (experiment 1). Milk production tended to be higher for concentrates including fish meal, in contrast to soyabean meal, particularly in the first half of the experimental period. However, milk fat content was significantly lower, resulting in similar productions of 4%-FCM. Extra concentrates in experiment 3 had significant positive effects on the production of milk, fat and protein, and also on milk protein content and liveweight gain. Feeding strategy however, was without any significant effect. It was concluded that with the high-yielding cows, offered roughages to appetite, there is no need to feed concentrates strictly to their estimated individual energy requirements. This may be of increasing importance when forage allowances/cow increase as a consequence of smaller numbers of cows/farm. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Compensatory milk production within the bovine udder: effects of short-term non-milking of single quarters

Daily quarter-milk yields of eight high-yielding cows (24-28 kg/d) and eight heifers (14-24 kg/d) were measured to examined to examined compensatory changes in milk production between quarters within an udder. Either one, two or three quarters per cow were left unmilked for 12 d, in early or late lactation, and then all quarters of all cows were milked normally for a further period of 12 d. Concentrate feeding levels were constant throughout the experiment. The mean daily yield per cow fell to 26, 59, and 75% during the period of milking either one, two or three quarters respectively. Twelve days after resumption of normal milking the total daily yield per cow was the same for cows continuously milked in two, three or all four quarters. Daily yield in cows with only one quarter milked continuously recovered to only 78% of the level of the pretreatment period. During the treatment period, the mean daily yield of the continuously milked quarters increased by almost 14% for cows milked in one quarter only, by more than 10% for two quarters milked, and by 4% per quarter if three quarters were milked. Milk yields of these quarters remained above their pretreatment levels when milking was resumed in the adjacent quarters. There was no difference in the compensatory effect between cows and heifers in early lactation, but the compensatory effects were lower in the lower in late lactation heifers.

The effect of forage supplementation, herbage height and season on the ingestive behaviour of dairy cows

In two experiments, in the early (May–July) and the late (August–October) part of the grazing season, the effect of offering first and third cut silages to Friesian dairy cows continuously grazed at 4- or 8-cm herbage height was investigated in Bangor, U.K. (53°N). There were no effects of silage type on ingestive behaviour. Grazing time decreased further when silage was fed at 4 than at 8 cm; this was caused by a decrease in bout number in early season and bout duration in late season. There were no effects of stage of the grazing season on grazing time, but grazing bout number was greatest and bout duration least in midsummer. Biting rate at pasture was increased at low herbage heights and was unaffected by offering silage. Biting rate declined as the season advanced. A circadian rhythm of biting rate was evident with an increase occurring between early morning and evening, and a reduction at or around dusk. Cows spent longer eating silage at the low herbage height and in late season. Ruminating time was increased by offering silage and was least in mid-season. There were no significant effects of yield level of the cows on grazing time, but high-yielding cows had reduced biting rates compared with low yielders. In late season, high yielders also had greater ruminating times than low yielders.

Thermal, Productive, and Reproductive Responses of High Yielding Cows Exposed to Short-Term Cooling in Summer

Effect of cooling on body temperature, milk production, estrous behavior, and reproductive performance was examined in 66 estrous-synchronized, Israeli-Holstein dairy cows. Cooling was by an automated system, which actuated sprinkling (30s) followed by forced ventilation (4.5min) for 30-min periods. Cows were cooled 9 times/d between 0500 and 2100h over 10 d, starting 1 d before expected estrus until d 8 post estrus. Cooling reduced typical diurnal rise of body temperature in summer heat-stressed cows by .5 to .9°C, and body temperature was maintained close to normothermic temperature (38.6°C). Milk production of cooled cows was 2.6 kg/d (+8%) above control at end of the cooling period. More cooled cows than noncooled exhibited standing estrous behavior; in noncooled cows, silent ovulations or anestrus were more frequent. Conception rate of cooled cows did not differ from control, suggesting need for a longer than a 10-d cooling period for improvement of fertility. The cooling system has potential to alleviate heat stress in dairy cows and to improve their thermal balance, productive, and reproductive performances.

Technical Evaluation of a Naso-Ruminal Instrument for Collection of Ruminal Samples in Non-Fistulated Cows

The sampling method used is of great importance for the estimation of the microbial activity and biochemical status in ruminal fluid (Stober & Tiefenbach 1958, Keindorf 1974, Behravesh 1984). Several methods have been used for sampling of ruminal fluid in non-fistulated animals (Sorensen & Schambye 1955, Perk 1958, Schultz & Hiepe 1958, Keindorf & Link 1971). However, the conventional methods of collecting ruminal fluid either by stomach tube (Thygesen probe with a filter ad modum Sorensen & Schambye (1955)), or through a puncture low in the left flank, do not produce representative samples comparable in quality or quantity to samples collected directly through a rumen fistula. The puncture methods usually produce a very small volume of material, and they often leave the cow with an inflammatory reaction in the flank. Many research workers have demonstrated contamination with saliva in samples drawn through a peroral stomach tube, resulting inter alia in a higher pH value than in samples collected through fistula (Dirksen 1970, Behravesh 1984). Since changes in the fermentative reactions of high-yielding cows are receiving much research emphasis today, it has been our aim to construct an instrument suitable for collecting single or continuous samples for diagnostic as well as research purposes, which are comparable in quality and quantity to samples obtained through a rumen fistula. The idea of making the naso-ruminal sampler was inspired by the construction of the COMET Naso-Reticular Instrument (Hekmati et al. 1985).

The influence of slowly and rapidly degradable concentrate protein on a number of blood parameters in dairy cattle.

In 3 feeding trials high-yielding cows and heifers (102, 72 and 92, respectively) were given diets from week 2 of lactation containing grass silage and maize silage and concentrates with slowly or rapidly degradable protein (DP). Diets were given according to the standard or slightly above the standard for digestible crude protein and net energy for milk production. A sample of peripheral blood was taken immediately before the morning feed and at 3-4.5 h after the concentrate was given. Blood urea was higher and blood glucogenic amino acids were lower (P

The effect of concentrate supplementation on high-yielding dairy cows under two systems of grazing

SummaryAn experiment with 36 high-yielding spring-calving cows studied the effect of 1 or 6 kg/day of concentrates offered to cows on either continuously stocked grazing or rotational strip grazing. A 4 × 4 latin-square design with periods of 3 weeks duration was adopted.Mean yield was 29 kg/day of fat corrected milk (FCM). The continuously stocked cows had higher milk yields, consumed more herbage organic matter, grazed longer, with bites of smaller size and responded less in total intake to the higher level of concentrates than the strip-grazed cows. The higher concentrate treatment increased milk yields but reduced fat contents so that the average response was 0·26 kg FCM/kg concentrate. There was no difference in response to concentrate allowance between grazing treatments.The differences recorded between grazing systems were attributable mainly to differences in green herbage allowance, which was greater with continuous grazing.

EFFECT OF FEEDING SOYBEAN MEAL PROTECTED WITH SODIUM HYDROXIDE, FRESH BLOOD, OR FISH HYDROLYSATE TO GROWING CALVES AND LACTATING DAIRY COWS

Soybean meal (SBM) protected from degradation in the rumen by NaOH, fresh blood (BL) or fish hydrolysate (FH) was evaluated in a digestibility and nitrogen (N) balance trial using weaned male Holstein calves and in a lactation trial (FH was not included) with multiparous high-yielding Holstein cows. N digestibility increased (P < 0.05) by inclusion of NaOH-treated SBM in the diet. N retention by calves increased (P < 0.05) with NaOH or BL treatment. DM intakes and milk composition in the lactation trial were not different across treatments. Milk yield, fat-corrected milk and solids-corrected milk yields and efficiency of protein utilization by cows fed NaOH-treated SBM diet were higher (P < 0.05) than by cows fed untreated SBM diet. These observations suggest that inclusion of NaOH- or BL-treated SBM results in improved protein utilization by young growing calves. NaOH treatment of SBM also results in production of more milk in high-yielding cows during early lactation. Key words: Soybean meal, sodium hydroxide, blood, fish hydrolysate, protected protein, calves, dairy cows

The effect of feeding in early lactation on feed intake, yields of milk, fat and protein and on live-weight change over one lactation cycle in dairy cows

SummaryAn experiment has been made to study the effect of level of feeding in early lactation on the feed intake, yields of milk, fat and protein and on live-weight change over one lactation cycle. Adult British Friesian cows of high potential yield were randomly allocated to high (HP) or moderate (MP) levels of feeding for 20 weeks. They were then randomly allocated within treatments to controlled or ad libitum levels of feeding for the rest of the lactation.There were significant effects of feeding in the early part of lactation on the yields of milk, protein and lactose but not on milk fat or live-weight change. Cows on the MP treatment produced about 450 kg milk from body energy reserves but were unable to supplement fully the dietary energy deficiency. There was no significant response to feeding ad libitum in the second part of lactation and the differences in yields established in the first part were maintained in the second. There was no relationship between feed intake and milk yield for cows fed ad libitum nor did the level of feeding in early lactation influence the level of intake in the later part.There was little agreement between calculated energy balance and the live-weight changes but there was more between live-weight change and condition score.

Evaluating feeding strategies for dairy cows: a modelling approach

ABSTRACTUsing a model to simulate food intake and the partition of food between milk production and live-weight gain, an attempt has been made to explore the financial implications of different levels and patterns of concentrate feeding, where silage is fed ad libitum. In the case of high-yielding cows it appeared that, although feeding more concentrates increased overall lactation yield, profits per cow and per hectare declined with increasing concentrate usage. This raises doubts concerning the traditional view that higher profits result from increasing yields per cow. Comparing different patterns of feeding it also appeared that there was no significant economic loss from flat-rate compared to stepped feeding of concentrates, where cows had ad libitum access to silage.

Metabolic Limits to Milk Production, Especially Roles of Growth Hormone and Insulin

Potential of the bovine mammary gland to synthesize milk probably is determined fully at parturition. Realization of that potential depends on the gland recieving adequate amounts of nutrients in the correct proportions. Provided the cow is fed adequately in relation to her potential yield, supply to the body of those nutrients that are absorbed directly from the gut is not likely to limit milk synthesis. Glucose and long-chain fatty acids, however, are not absorbed from the gut in adequate amounts, and metabolic factors (primarily hormonal regulation) determining the supply of these may be important limits to milk synthesis.Even when amounts and proportions of metabolites entering circulation are adequate for maintenance and maximum milk synthesis, the cow's potential cannot be realized fully unless nutrients are channeled selectively towards the mammary gland. This occurs naturally in the high-yielding cow in early lactation and probably can be maintained artificially into midlactation by use of growth hormone. Consequences of this on milk output, health, and reproductive performance are considered.