Milk Yield Potential Research Articles

The effect of incremental changes in metabolisable energy intake on the partitioning of metabolisable energy in dairy cows

The current energy (E) feeding standards (AFRC, 1993) have the objective of providing accurate feeding of dairy cows when there is either zero tissue E retention or a given tissue E change. Such approaches are of limited practical value in the real world in which we must be able to predict optimum feeding levels and strategies for animals of differing milk yield potential producing in a range of physical and economic environments. In the latter context the key economic factor is how the animal responds to additional increments of feed. This is primarily driven by how the animal partitions that additional E between milk output and body tissue gain. The objective of this experiment was to use calorimetric techniques to explore the impact of level of metabolisable E (ME) intake (MEI) on milk E output (E1) and tissue E gain (Eg) and hence partitioning of increments of MEI between milk and tissues.

Glucose metabolism in vivo in crossbred Holstein cattle feeding on different types of roughage during late pregnancy and early lactation

An experiment was carried out to study the glucose kinetics of crossbred Holstein cattle feeding on either hay or 5% urea treated rice straw during late pregnancy (21 days prepartum) and early lactation (30 days postpartum). In all 16 pregnant heifers (23–25 months of age) were selected for the experiments, including eight animals of two breed types, Holstein Friesian×Red Sindhi (50:50=50% HF) and Holstein Friesian×Red Sindhi (87.5:12.5=87.5% HF). They were divided into four groups of four animals each. Animals from the same breed type in each group were fed with either rice straw treated with 5% urea or pangola hay ( Digitaria decumbens) as the source of roughage throughout the experiments. The glucose turnover rate in both types of crossbred Holstein cattle was determined using a continuous infusion of [U- 14C] and 3-[ 3H]glucose during late pregnancy and early lactation. Total glucose entry and utilization rates increased significantly during lactation for all groups. Recycling of [C]glucose was, approximately, 20% in both crossbred cattle fed either hay or urea treated rice straw and was unaffected by the stage of late pregnancy or early lactation. Comparing 50 and 87.5% HF animals, arterial plasma glucose concentrations were slightly higher during pregnant periods but significantly higher in lactating periods in 50% HF animals. The ratio of specific radioactivity of arterial blood bicarbonate relative to that of arterial blood [ 14C]glucose in the lactating period, significantly decreased in 50% HF animals fed either urea treated rice straw or hay. An increase in udder blood flow during early lactation was significantly higher in 87.5% HF animals than in 50% HF animals. The uptake, arteriovenous differences and extraction ratio for glucose across the udder, significantly increased in the lactating period for all crossbred animals. Glucose uptake by the udder of 87.5% HF animals accounted for 65% of the total glucose turnover rate compared to a value of 46% in the lactating 50% HF animals. It can be concluded that both crossbred cattle fed either urea treated rice straw or hay exhibit the same body glucose turnover rate. The 87.5% HF animal has the genetic potential for a high milk yield and has high body and udder glucose metabolisms compared with 50% HF animals.

A preliminary cost-benefit analysis for inclusion of caucasian clover in new dairy pasture

In a coastal Bay of Plenty trial, ryegrass pasture containing the rhizomatous legume caucasian clover (CC), provided advantages from late spring to autumn in total herbage yield and legume content in the 2nd to 4th years, compared with a ryegrass- white clover pasture. Sub-optimal pasture supply and quality, in summer and autumn especially, can limit seasonal milk production potential. Thus, greater milk yield from pasture which includes CC can be derived from greater dry matter on offer to cows, and also through improved forage quality afforded by increased legume content. CC is slower to establish than white clover (WC) and may be favoured by spring rather than autumn sowing. The extra costs for successfully establishing CC in pasture and the milk yield potential from greater herbage yields and legume content were used to determine the level and rate of economic benefit from its inclusion in dairy pasture. Depending on the assumptions made, CC was calculated to recover net establishment costs in the 4th year, with a net present value over 10 years of $789, or a 35% internal rate of return. At this level of return use of CC in pasture renewal would be an attractive longerterm option. A number of considerations, which need to be taken into account, include as yet unestablished benefits for CC on heavier or moister soils which are less compromising to WC persistence, the slow establishment of CC, the effects of different methods of establishment and longer-term effects of pasture pests on its performance potential. Keywords: caucasian clover, cost-benefit, coastal Bay of Plenty, dairy pasture, Lolium perenne, Trifolium ambiguum, Trifolium repens

Targets for rearing dairy heifers - weaning to calving

THE management of dairy heifers between weaning and calving has a considerable effect on potential milk yield, fertility, the incidence of difficult calvings, and longevity. Insufficient growth during the rearing...

Performance of Lactating Dairy Cows Fed Red Clover or Alfalfa Silage

The objective of this study was to compare utilization of red clover (Trifolium pratense L.) and alfalfa (Medicago sativa L.) by lactating dairy cows. Red clover and alfalfa were harvested and conserved as silage at two maturities in 2 consecutive yr. Each year, diets containing experimental forages and supplemental grain were fed to 16 multiparous Holstein cows in early lactation in a replicated 4 × 4 Latin square lactation trial. Lactation performance and nutrient intake responses caused by forage type (red clover vs. alfalfa), maturity (early vs. late), and equivalent acid detergent fiber (ADF) content (yr 1, late alfalfa vs. late red clover; yr 2, early alfalfa vs. late red clover) were compared. Milk yield was not different between cows fed red clover or alfalfa in yr 1, but milk yield was higher for cows fed red clover in yr 2. When cows were fed alfalfa and red clover with similar ADF content, the milk yield of cows fed red clover was lower than that of cows fed alfalfa in yr 1, and milk yields were similar between cows fed alfalfa and red clover in yr 2. Milk protein yield and percentage were lower for cows fed red clover in yr 1 and 2, respectively. Intake of ADF and neutral detergent fiber was lower for cows fed red clover in both years. When red clover contained the same ADF content as did alfalfa, cows fed red clover ate less ADF, neutral detergent fiber, and dry matter, resulting in lower milk yield potential.

Influence of prepubertal feeding level on milk yield potential of dairy heifers: a review.

In replacement heifers, high levels of feeding resulting in high growth rates in the prepubertal period can cause severe reduction of the milk production potential. This has been demonstrated in many experiments; however, there are a number of experiments where this effect is not seen. In many cases, the reason for the lack of effect seems fairly obvious (short treatment periods, high pretreatment growth rates, small growth rate differences between treatment groups, variation of growth rates within treatment groups, treatment periods outside the critical period, etc.). However, in a few experiments absence of treatment effect cannot be explained in this way. This demonstrates that our knowledge on the effect of nutrition during rearing on the future milk yield of heifers is incomplete and that it may be possible to develop high growth rate feeding regimens for heifers. Experimental evidence suggests that the observed negative effects of feeding level on subsequent milk are due to impaired mammary development. Development of suitable high growth rate feeding regimens therefore requires understanding of the influence of nutrition on the physiological regulation of mammary development. Available data suggest that the growth hormone-insulin-like growth factor I axis is involved, but it is not clear how. It is likely that understanding of the role of insulin-like growth factor binding proteins is important. Alternative hypotheses involve possible effects of growth factors and modifications of mammary tissue sensitivity to hormones and growth factors.

A comparison of offering a high level of concentrates through an out-of-parlour feeder or within a complete diet using high merit cows

The genetic merit of the UK dairy herd is increasing rapidly. With cows of higher milk yield potential and higher nutrient requirements, the level of concentrate feeding is likely to increase. Previous studies have shown little benefit with complete diet feeding with cows of medium genetic merit at moderate levels of concentrate feeding (Agnew and Mayne, 1992; Agnew, Mayne and Doherty, 1996). The objective of the present study was to compare offering a high level of concentrates (mean 11.1 kg DM/day) to high genetic merit cows, either separately from the silage using an out-of-parlour (OP) feeder or within a complete diet (CD) system).

The responses of high and medium merit dairy cows to diets differing in grass silage: concentrate ratios, during early lactation

The genetic merit of the UK dairy herd is increasing rapidly and this trend is likely to continue for the forseeable future. With cows of higher milk yield potential and higher nutrient requirements, feeding systems developed in the past with medium genetic merit animals, may now need to be adapted to meet the needs of high genetic merit animals if nutrition x genotype interactions exist. This would be particularly true to increasing proportion of concentrates in grass silage based diets. This study was undertaken to compare the milk yield responses of high and medium merit dairy cows.

The responses of high and medium merit dairy cows to diets differing in grass silage: concentrate ratios, during early lactation

The genetic merit of the UK dairy herd is increasing rapidly and this trend is likely to continue for the forseeable future. With cows of higher milk yield potential and higher nutrient requirements, feeding systems developed in the past with medium genetic merit animals, may now need to be adapted to meet the needs of high genetic merit animals if nutrition x genotype interactions exist. This would be particularly true to increasing proportion of concentrates in grass silage based diets. This study was undertaken to compare the milk yield responses of high and medium merit dairy cows.

Genetic variation in the feeding efficiency of maize genotypes evaluated from experiments with dairy cows

AbstractGenetic variation in the feeding efficiency of maize genotypes was evaluated from experiments with dairy cows. Maize genotypes were chosen to represent a range of digestibilities from previous experiments with standard sheep.The variation in milk yield observed with dairy cows fed genotypes with low or high digestibilities or energy values was about 1.0–2.0 kg per animal per day. Moreover, the range of variation in body weight was about 10–30 kg during the 3 months of the experiments. Hybrids with similar energy values had a similar effect on milk yield, but the intake of each hybrid could be very different when they were fed to dairy cows, even if no difference in intake had been observed in sheep. The higher silage maize intake of ‘DK265’ was mostly converted into a body weight gain rather than an increased milk yield, probably because the milk yield potential of the animals was soon reached. It appeared that those hybrids whose predicted energy value from sheep measurements was low led to relatively low performances in cows. Dairy cow performances also appeared to be related to the enzymatic solubility values of the whole plants.For maize breeders, the prediction of hybrid efficiency in dairy cow rearing must include digestibility and ingestibility factors. The most important challenge for maize breeders now will probably be the adjustment of a criterion for predicting intake because the stover digestibility and the starch content can be predicted reliably with the use of NIRS calibrations.

An investigation of the effect of initial milk yield level on the response to sward height and concentrate supplementation in grazing dairy cows

The increase of milk yield potential of dairy cows raises a number of questions relating to their management at pasture where the intake potential might be limiting. The interaction of initial milk yield (IMY), sward availability (SH) and level of concentrate supplementation (CI) is largely unknown.Two experiments of 42 and 24 days in spring and midsummer were carried out with 45 and 27 Holstein Friesian cows respectively. In spring, five IMY groups (range 16.9 to 35.5 kg/day) and in midsummer three IMY groups (range 22.2 to 31.8 kg/day) were used. In both periods, three compressed sward height(3 to 5, 5 to 7 and 7 to 9 cm) and three CI (0, 3 and 6 kg/day, with 160 g CP/kg DM, 12.8 MJ ME/kg DM) were used. The grazing area consisted of 7.9 ha of perennial ryegrass which was set stocked. The herbage intake (HDMI) was estimated indirectly from individual cow performance. Grazing time (GT) was recorded for each cow on 24 hour observations. Multiple regression analyses were carried out relating the dependent variables herbage intake, grazing behaviour and milk production to the independent variables (IMY, SH, CI).

An investigation of the effect of initial milk yield level on the response to sward height and concentrate supplementation in grazing dairy cows

The increase of milk yield potential of dairy cows raises a number of questions relating to their management at pasture where the intake potential might be limiting. The interaction of initial milk yield (IMY), sward availability (SH) and level of concentrate supplementation (CI) is largely unknown.Two experiments of 42 and 24 days in spring and midsummer were carried out with 45 and 27 Holstein Friesian cows respectively. In spring, five IMY groups (range 16.9 to 35.5 kg/day) and in midsummer three IMY groups (range 22.2 to 31.8 kg/day) were used. In both periods, three compressed sward height(3 to 5, 5 to 7 and 7 to 9 cm) and three CI (0, 3 and 6 kg/day, with 160 g CP/kg DM, 12.8 MJ ME/kg DM) were used. The grazing area consisted of 7.9 ha of perennial ryegrass which was set stocked. The herbage intake (HDMI) was estimated indirectly from individual cow performance. Grazing time (GT) was recorded for each cow on 24 hour observations. Multiple regression analyses were carried out relating the dependent variables herbage intake, grazing behaviour and milk production to the independent variables (IMY, SH, CI).

The effect of genotype × environment interactions on biological efficiency in beef cows

AbstractAn experiment was conducted to examine the response of three genotypes of beef cows to contrasting levels of nutrition supplied from grazed pasture. Twenty-two Hereford × Friesian (HF), 20 Aberdeen Angus × Friesian (AF) and 24 Welsh Black (WB) spring-calving beef cows with their Charolais-cross calves were used in 4 years consecutively. During the summer grazing period they grazed permanent pasture maintained at either 4 to 5 cm (short) or 7 to 8 cm (tall) sward surface height. Sward height treatment significantly (P < 0·001) affected cow and calf live-weight gain (0·498 v. 0·041 (s.e.d. 0·0405) kg/day and 1·12 v. 0·90 (s.e.d. 0·021) kg/day for cow and calf live-weight gain on the tall and short swards respectively). The live-weight gains of the HF and WB cows were similar, but the AF cows gained less weight on the tall sward and lost weight on the short sward. Calf live-weight gain reflected cow milk yield, with the calves from HF and AF cows having similar live weight gains (1·06 and 1·02 kg/day respectively) and those from WB cows having lower gains (0·95 kg/day; P < 0·001). The effect of sward height on calf live-weight gain was greatest in the WB-born calves because of the lower milk yield from WB cows. Body chemical composition changes of cows were predicted from live weight and body condition score, using prediction equations derived from separate groups of cows which were slaughtered at a range of body compositions for determination of chemical composition. Energy balances, calculated from changes in chemical composition, showed the AF cows to have the lowest energy balances with the WB cows the highest. Calculation of energetic efficiency and land use efficiency of weaned calf production taking account of annual food requirements indicated that the HF cows were most efficient, and the WB cows least efficient. The effect of increasing nutritional environment (as represented by sward height treatment) was such as to increase energetic efficiency for all genotypes, but land use efficiency was increased for HF and AF cows, and decreased for WB cows. These results indicate the factors such as size of cows, milk yield potential and pattern of nutrient partitioning can influence energetic land use efficiency of weaned calf production, and that important interactions between genotype and nutritional environment can occur in different measures of efficiency.

Relationship between milk acetone and milk yield in individual cows.

Correlations between acetone in milk and milk production during the first nine weeks postpartum were calculated in ten individual cows and for a whole herd. The decrease in milk production due to ketonaemia was evaluated using a mathematical model of the KaleidaGraph integrate area program. For determination of milk components, a milk sample was obtained twice a week from one to nine weeks postpartum. Milk yield was negatively correlated with acetone concentration in milk. In non-clinical ketotic cows the calculated loss of milk yield due to elevation of milk acetone was 2-9% and in clinical ketotic cow it was as high as 26%. The correlation between milk components and acetone level varied at different stages of ketosis. Thus the stage of lactation and of ketosis should be taken into consideration when the correlation between milk parameters and milk production is evaluated. Prior to clinical ketosis, milk acetone was negatively correlated with milk yield, percentage of protein and percentage of lactose, whereas it was positively correlated with percentage of fat and urea concentration. In addition, high levels of acetone tended to be associated with high cell count. It is concluded that 1) ketotic cows do not achieve the maximum potential milk yield and 2) high levels of milk acetone are harmful to the udder. For high milk production, the concentration of acetone in milk should not exceed 0.05 mmol/l at any stage of lactation.

Relationships between subclinical ketosis, milk production and fertility in Finnish dairy cattle

The relationships between milk production, subclinical ketosis and fertility were studied in 101 dairy cows in central Finland. For determination of milk components, individual milk samples were obtained in three successive, monthly milk recordings. The metabolic balance of the cows was determined by acetone and urea assays of milk. In addition, at dry-off a milk sample was obtained and the body condition score was determined. At 3–4 weeks postpartum (p.p.), low acetone concentrations in milk were associated with high milk yield and with high yield of milk protein at 3–4 and 7–8 weeks, whereas there was only a slight negative correlation between yield of milk fat and acetone concentration. At 7–8 weeks p.p., high levels of acetone were correlated with a high percentage of milk fat and with a low percentage of milk protein in the third milk recording. At 3–4 weeks p.p. a high percentage of milk fat and a low protein: fat ratio were correlated with high acetone at 7–8 weeks. High acetone level at Test 2 was correlated with high milk yield at Test 3. At dry-off, high levels of urea were associated with a low percentage of milk protein at the first and second milk recording of the next lactation. Cows with fat body condition had a high percentage of milk fat and a low protein: fat ratio. The yield of milk protein and of milk at 3–4 weeks p.p. affected the interval from calving to conception ( r=0.31). The time from calving to conception also was associated with high protein yield, high milk yield and high fat yield at 7–8 weeks p.p. ( r=0.41, r=0.40 and r=0.35, respectively). At the third milk recording, a low percentage of milk protein was associated with a long interval from calving to first insemination and to conception ( r=0.22 and r=0.26, respectively). We conclude that subclinical bovine ketosis in early lactation reduces milk production. Subclinically ketotic cows might not achieve the maximum potential milk yield. In an individual cow, high milk production as a result of the low energy balance in puerperium curtails reproductive performance. At dry-off, overfeeding is associated with a low protein: fat ratio early in the next lactation.

Relationship of post-partum interval in mature beef cows with nutritional environment, biological type and serum IGF-1 concentrations

AbstractMature cows of nine breeds were fed (four cows per level within breed) at either 0·55, 0·71, 0·88 or 1·05 MJ metabolizable energy (ME) per kg initial body weight0·75 per day during non-lactational periods for an average of 4 years. During lactation, energy allowances were increased by 0·17 MJ ME per kg body weight0·75 per day. Breeds represented four biological types: moderate genetic potential for milk yield and growth (Angus, Hereford, Red Poll), moderate milk and high growth (Charolais, Eimousin), high milk and moderate growth (Braunvieh, Pinzgauer) and high milk and growth (Gelbvieh, Simmental). The objective was to test the effects of biological type and nutritional environment on length of post-partum interval as determined from serum progesterone levels. The potential of serum insulin-like growth factor-1 (IGF-1) level at 3 weeks post partum for predicting the length of the post-partum interval was also evaluated. Non-parametric statistical analyses appropriate for right-censored survival data were used to test effects on post-partum interval because collection of serum was terminated prior to ovulation in some cows.Energy availability × biological type effects on post-partum interval were significant. Increased energy availability tended to decrease post-partum interval in all biological types with high potential growth types exhibiting the greatest positive response to increased food. Post-partum interval for types with high growth potential was shorter within food level when associated with high rather than moderate potential for milk yield. Serum IGF-1 was related to post-partum interval at lower energy availability but appeared to have limited usefulness for identifying cows with extended intervals. Inherent direct and maternal production potential interact with available food resources to influence the post-partum interval of mature beef cows.

An adaptive decision-making aid for dairy cow replacement

A decision aid is developed for the retention or replacement of individual dairy cows. An important determining factor is the cow's milk-yield potential. However, the potential is difficult to assess from recorded yields in previous lactations because temporary environmental factors mask the underlying yield potential. An optimal replacement strategy can be found using stochastic dynamic programming. In this paper the approach is extended to allow for the Bayesian re-evaluation of yield potential on the basis of previous recorded yields. The sensitivity of the replacement decision to variance estimates determined for a sample of commercial dairy herds in England and Wales is tested in an adaptive dynamic programming model. The paper concludes by demonstrating the way in which the model results could be used for helping to identify which cows should be culled without replacement if the expected milk production of the herd is above the quota limit.

Yield and Reproduction Characteristics of Friesian Cattle Under North African Conditions

Analyses of data from 156 dairy herds identified significant sources of variation by region, herd within region, month, and year of calving for milk yield, fat yield, and fat percentage. Friesian cows in Tunisia reached their maximum milk yield between 63 and 84 mo of age. The average milk yield was 4000kg, fat yield was 177kg, and fat percentage was 2.93%. These averages were not adjusted for DIM or age at calving. Differences among the three strains of Holsteins in this study were generally small and non-significant. Friesian cows born and raised in Tunisia tended to have shorter lactations than imported cattle. North American Holsteins tended to have more DIM than European Friesians. Friesians born and raised in Tunisia had the lowest milk yield: about 9% less than North American Holsteins. European Friesians yielded more than cattle developed locally, but they still yielded about 6% less than North American Holsteins. The DIM was considered to be an environmental variable rather than a consequence of low milk yield potential. Cows calving in August yielded 384kg less milk than cows calving in January. Adjustment factors for DIM, age, and month of calving were developed to enhance the use of dairy records.

Comparative Responses of Lactating Cows to Total Mixed Rations or Computerized Individual Concentrates Feeding

A trial was conducted in a commercial dairy herd in which the concentrate part of the ration was fed individually to a group of cows through computerized self-feeders. Performance results were compared with those of a group fed TMR of 65 to 67% concentrates. Rationing of individual concentrates was according to parity, milk yield, milk yield potential, BW changes, and bunk feedstuffs. Mean intake of concentrates per cow was about 1 kg/d lower in the individually supplemented cows. This was partly compensated for by a higher intake of bunk feedstuffs. Overall daily milk yield per cow was similar to those receiving a TMR in first parity cows, higher in second parity cows, and lower in third and greater parity cows. The higher performance of the second parity cows was achieved in all milk yield potential classes, and the lower yield in subsequent lactations was due to lower performance in low and high potential classes. The individually supplemented cows gained less BW than those in the TMR group. Milk yield per unit of BW was better than milk yield as a variable to refine individual cow supplementation strategy for allocation of concentrates. Results also suggest that the same criteria used for supplementation of concentrates can be beneficial to cows’ assignments and movements among different TMR groups. Computerized dispensing of concentrates, when applied properly, can economize on consumption of concentrates when grouping and feeding different TMR are impossible.

THE SKOPELOS GOAT BREED OF GREECE

SUMMARYIn the Northern Sporades islands of the Aegean Sea a goat population isolate exists with an exceptional milk yield potential (225 kg marketed milk from average lactations of 174 days). The prolificacy is 135% and the average adult live weight of the females 56 kg.While the actual purebred “Skopelos” population is estimated at only 8000 goats, the development of recording and a breed selection programme, combined with a necessary conservation policy, should help preserve the breed and assure its development possibilities.