And, in addition to previously identified benefits, if TM-QTL were included in breeding programmes to produce homozygote carrier lambs, meat yield could be increased in carcasses of equal weight.

A myriad of exciting results for sheep breeders and lamb producers from one study, which set out to examine TM-QTL effects on carcass composition and weight distribution in Texel lambs, the findings of which were presented to delegates at this year’s British Society of Animal Science’s annual conference, held at the University of Nottingham.

“TM-QTL is a QTL that increases loin muscling by between 4% and 11% in Texel lambs and Texel-sired crossbred lambs with a polar over-dominant action (phenotype is expressed only if one copy is inherited from sire) and has an additive effect on carcass weight,” explained the Scottish Agricultural College’s Jenny Macfarlane. Her team’s study involved purebred Texel lambs.

After slaughter, carcasses were chilled for seven, eight or nine days, weighed, split and each side cut into fore-quarter (FORE ¼), saddle (SADDLE) and hind-quarter (HIND ¼). These were weighed and butchered into lean meat (LMY), fat trim and bone. The proportion of total carcass weight contained in each region and proportion of LMY, fat trim and bone in the carcass were calculated.

Lambs were blood-sampled and TM-QTL genotypes assigned and is was found that there were 40 non-carriers (+/+), 17 heterozygote carriers inheriting TM-QTL from the dam (+/TM), 53 heterozygote carriers inheriting TM-QTL from the sire (TM/+), 34 homozygote carriers (TM/TM) and 65 with unknown genotype.

“Analysis of the results revealed that,  when adjusted for CWT, there were no significant differences between genotypes for weights in each area or the proportion of total CWT contained in each carcass area,” said Dr Macfarlane. “LMY/CWT was 1.36 to 2.37% higher in TM/TM compared to the other groups although the difference was significant only for TM/TM vs. +/TM. FAT/CWT and BONE/CWT were not significantly different between genotypes,” she added.

Presented to the British Society of Animal Science Annual Conference, April 4 to 5, 2011, University of Nottingham University, UK.

Full details: MacFarlane JM, Lambe NR, McLean KA, Wolf BT, Haresign W and Bunger L: “Effect of the Texel muscling quantitative trait locus (TM-QTL) on fore quarter, hind quarter and saddle weights, weight distribution and carcass composition in purebred Texel lambs.”

Presented to the British Society of Animal Science Annual Conference, April 4 - 5, 2011, University of Nottingham, UK.

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The effects of the TM-QTL on meat quality traits for the semimembranosus muscle in purebred Texel lamb were negligible in a trail where lamb had been aged for seven or more days.  But all meat quality traits were significantly affected by sex, with females having better figures.

Two interesting findings, presented to delegates at this year’s British Society of Animal Science’s annual conference, held at the University of Nottingham, from studies carried out in Scotland and New Zealand.

The TM-QTL located on chromosome 18 increases loin muscle dimensions and weights, by between 4% to 14%, in purebred and crossbred carrier Texel lambs, but other muscles seem to be unaffected.

“Studies have revealed that TM-QTL had no detrimental effects on tenderness of Longissimus lumborum or vastus lateralis muscles of purebred Texel lambs, but before the TM-QTL can be recommended to industry it is important to assess its effects on other meat quality (MQ) traits,” said the Scottish Agricultural College’s Cameron Craigie, who led the joint trails that examined the gene’s effect on the semimembranosus (SM) muscle including additional meat quality traits.

Purebred Texel lambs were slaughtered at a mean age of 144 days with a mean hot carcass weight of 15.2kg. After electrical stimulation and kept at 2°C for either seven or nine days, the topside cut that contains the adductor and gracilis muscles was taken from the right side of each carcass. A cut surface of SM was allowed to bloom for one hour before colour measurements and pHs were recorded.

Samples were stored in sealed plastic bags and frozen (-30°C), were later defrosted in 17 batches for 24 hours at 3°C. A 50 g cut of the SM was weighed prior to cooking in a polythene bag in a 70°C water bath for 90 minutes. After cooking, fluid was drained off and samples stored overnight at 3°C.

The next day, samples were weighed after drying with a paper towel, to determine cooking loss as a percentage of uncooked weight. Twelve shears, perpendicular to the fibre axis were performed on six 13 mm by 13 mm by 25 mm cores using a modified Warner-Bratzler protocol.

“And we found no significant differences between genotypes within sex, but there were significant sex differences irrespective of genotype, with females having better meat quality,” said Mr Craigie.

Full details: Craigie CR, Lambe NR, MacFarlane JM, Maltin CA, Morris ST, Roehe R and Bunger L: “Effect of the Texel muscling quantitative trait locus (TM-QTL) and sex on meat quality parameters of the semimembranosus muscle of purebred Texel lambs.”

Presented to the British Society of Animal Science Annual Conference, April 4 - 5, 2011, University of Nottingham, UK.

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Some interesting results for sheep producers, looking to improve their hill-farm finishing systems and maximise productivity and profitability.

However, scientists at Northern Ireland’s Agri-food and Biosciences Institute added that lamb growth rates on forage-based diets are approximately only 50% of the growth rates reported for lambs finished on concentrates, when they presented the results of their work to delegates at this year’s British Society of Animal Science’s annual conference, held at the University of Nottingham.

Finishing hill lambs on lowland farms is an important feature of the UK sheep industry and a major contributor to the rural economy. Historically, due to their low growth potential, hill lambs were finished on high grain diets in order to achieve moderate-to-high growth rates. “But concentrate feed costs have increased significantly in recent years so that there is a need now to investigate lower cost forage-based alternatives,” said Ronald Annett, explaining the rationale behind his work.

“Silage-based diets for lambs have been studied extensively and are capable of sustaining growth rates of between 80g and 130g/day. Forage maize can also be a high quality feedstuff and has the potential to reduce feeding costs on mixed beef/sheep farms.

“But there is only limited information on the performance of lambs fed maize silage-based diets. Grazed grass is the cheapest forage available for lambs, but the low nutritive value of late season grass swards may make grazed grass inadequate to maintain high levels of performance.

“We wanted to investigate the performance and carcass characteristics of lambs finished on a range of forage-based diets,” he added.

A total of 136 castrate male lambs were sourced from six hill farms soon after weaning.
Following a three-week acclimatisation period, the lambs were allocated to three treatment groups.

Within each treatment group, lambs were randomly allocated for slaughter at 42, 46 and 50 kg live weight. Two treatment groups were housed as groups of six lambs per pen and finished on ad lib grass silage (GS) or ad lib maize silage (MS) and concentrates. The remaining lambs were grazed together on a mixed perennial ryegrass/Italian ryegrass sward (GG).

Lambs were weighed fortnightly until they reached their target slaughter weight. Cold carcass weight, dressing proportion and grade were recorded at slaughter. Carcass conformation was scored on a five-point scale using the EUROP classification system while carcass fatness was scored on a six-point scale using the Livestock and Meat Commission (NI) classification system

“Lambs fed GG had higher live weight gains and achieved 20 kg carcass weight on average 22 days earlier than those fed GS,” said Dr Annett. “Lambs fed MS consumed 20% more silage DM and, as a result, achieved 20 g/d higher live weight gains and were slaughtered 12 days earlier than those fed GS.

“But MS tended to reduce carcass dressing proportion and consequently tended to increase slaughter weight compared with GS, so reducing the benefits of their higher weight gains for age at slaughter.”

He added that there was no effect of forage type on carcass conformation score. However lambs finished outdoors on GG had lower fat scores compared with those finished indoors on silage-based diets.

Full details: Annett RW and Carson AF: “A comparison of growth and carcass characteristics of hill lambs finished on a selection of forage-based diets.”

Presented to the British Society of Animal Science Annual Conference, April 4 - 5, 2011, University of Nottingham, UK.

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Spine characteristics differ between sheep breeds, indicating that there could be a genetic basis for variation.  And a trial has revealed evidence of a considerable amount of variation in the length of individual vertebrae.

“Future intra-breed estimations of genetic parameters should further evaluate this underlying variation and its genetic basis, including any possible effects on meat yield traits, revealing the potential of spine characteristics to be useful as selection traits,” the Scottish Agricultural College’s Claire Donaldson told delegates at this year’s British Society of Animal Science’s annual conference, held at the University of Nottingham.

The longissimus (loin) muscle is one of the higher priced cuts of meat and commercially one of the most important muscles. The muscle runs the length of the spinal column, so animals with short backs (reduced number or length of vertebrae) have a reduced length of longissimus muscle.

A number of studies on pigs have described variation in vertebrae number in the lumbar and thoracic regions of the spine and indicate a genetic basis for this. This has led to significant attention by breeders, as a way of increasing the production of meat from these popular cuts in pigs, in particular, via a genetic change of spine characteristics.

“In comparison to the knowledge in pigs, there is little yet known in sheep regarding this topic, so this study aims to investigate variation in spine characteristics (vertebrae length and number) and to assess the differences between males and females and within and between breeds of sheep,” said Miss Donaldson, explaining the rationale behind her team’s work.

 Lambs reared in different years were scanned using X-ray computed tomography (CT) at 20 weeks of age. The total sample included animals from four different breeds or crosses: Texel (TEX), Scottish Blackface (SBF), Texel cross Mule (TEX x MULE) and Poll Dorset cross Mule (PD x MULE).

Topograms generated from the CT scans were used to quantify the skeletal/spine characteristics of two regions of the spine (thoracic and lumbar). Each spine region was first treated individually and measurements taken for every animal included: counts of vertebrae number in the lumbar and thoracic regions, lengths (mm) of the lumbar and thoracic regions of the spine, and the average length (mm) of individual vertebrae in the lumbar and thoracic regions.

The two results were then combined to give thoracolumbar (thoracic + lumbar) measurements, which included the total count of vertebrae, total length (mm) of the thoracolumbar region, and the average length (mm) of individual vertebrae across the thoracolumbar region.

“And data analysis revealed that there were no significant sex effects on the majority of the spine traits,” said Miss Donaldson. “But breed/cross appears to have significant effects on all spine characteristics. For example, vertebral counts were significantly lower in TEX compared to SBF and the crosses.

“All vertebral length measurements (SPL and VL) showed significant differences across breeds/crosses, with lowest values for TEX and the majority of the higher values in the crosses, particularly the PD x MULE lambs,” she added.

Full details: Donaldson CL, Lambe NR, MacFarlane JM, McLean KA, Maltin CA and Bunger L: “Breed and sex effects on spine characteristics in sheep.”

Presented to the British Society of Animal Science Annual Conference, April 4 - 5, 2011, University of Nottingham, UK.

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Finishing lambs on chicory resulted in heavier carcases with better killing-out percentages and conformation scores, without detrimental effects on overall sensory meat eating quality. Great news for sheep producers, looking to fatten lambs on alternative finishing forages.

Finishing lambs on chicory is increasingly popular as it may support higher growth rates than grass/clover, particularly in the face of gastrointestinal nematode parasitism.

“However, impact on meat eating quality is largely unknown. We have reported that chicory grazing increased killing out (KO) percentage, without detrimental effects on meat eating quality, and increased loin juiciness in female lambs,” the Scottish Agricultural College’s Jos Houdijk told delegates at this year’s British Society of Animal Science’s annual conference, held at the University of Nottingham.

“However, castrated and female lambs were allocated to different taste panels, and lambs were not finished to commercial standards. So we set out to assess the effect of sex and chicory grazing on KO percentage, carcass conformation score and sensory meat eating quality in commercially finished lambs.”

Lambs grazed pure stands of chicory (CH) or grass/clover (GC) from birth to slaughter at 193 days of age. Body weight taken just before slaughter and carcass weights defined KO percentage as 100%. EUROP carcass grades taken were transformed into scores for analysis for conformation grades and for fat grades.

Carcasses were hip-suspended at 2°C for 24 hours before posterior 20cm of left loin were retrieved, matured at 2°C for another nine days in vacuum bags and frozen pending sensory quality assessment at University of Bristol.

Loins were thawed overnight, de-boned on the assessment day, cut in 8-10 2-cm thick samples and cooked until internal temperature reached 75°C. And samples were placed in an incubator (60 ºC) prior to sampling by 10 qualified assessors, who were asked to rate eight-point category scales for tenderness, juiciness, lamb flavour intensity, abnormal lamb flavour intensity and two hedonic scales for flavour liking and overall liking.

“And we found that  CH and GC lambs weighed 46.9 and 45.1kg, respectively at slaughter, and their KO percentages were 46.8 and 44.6%, respectively,” said Dr Houdijk.

“Carcass fat scores were similar, but CH had higher conformation scores than GC. CH and GC lambs had an average carcass grading of U3L and R3L, respectively. Sex did not affect weight, KO and carcass grades, and neither forage nor sex affected hedonic flavour and overall liking,” he added.
 
Full details: Houdijk JGM, Baker A, Navajas EA, Richardson RI and Ross DW: “Finishing lambs on chicory increases killing out percentage and carcass conformation score without detrimental effects on sensory meat eating quality.”

Presented to the British Society of Animal Science Annual Conference, April 4 - 5, 2011, University of Nottingham, UK.

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 “The aim of our two studies was to investigate the effects of replacing ZnO with Bioplex® Zn on performance of pregnant ewes and their lambs,” explained Miss Cave.

Twin-bearing Suffolk cross North Country mule ewes (33 in experiment one and 48 in experiment two) were individually penned from six weeks pre-partum to four weeks post-partum and fed an isonitrogenous, isoenergetic concentrate diet containing one of three treatments: control (no supplemental Zn); ZnO (an additional 50 mg Zn/kg DM as ZnO); or Bioplex® Zn (an additional 50mg Zn/kg DM as Bioplex Zn).

In experiment one the basal diet contained 81mg Zn/kgDM and in experiment two it contained 46mg Zn/kg DM. At four weeks of age lambs were offered ad lib. creep, which was an isonitrogenous, isoenergetic, high fibre concentrate feed. Lambs were weaned at eight weeks of age.

In experiment one, the creep, which contained a basal level of 140 mg Zn/kg DM, contained no supplemental Zn. In experiment two, creep contained the same level and source of supplemental Zn as fed to the dam, with a basal level of 52 mg Zn/kg DM.

In experiment two, one lamb from each ewe was individually penned at weaning until 15 weeks of age and given ad lib. creep containing the same level and source of supplementary Zn as the dam. Ewes and lambs were weighed on a weekly basis in both experiments.

In the second experiment, ewe hoof hardness was measured at lambing and the results were analysed.

“There were no significant effects of supplementing the control diet with 50mg Zn/kg DM on ewe live weight change, lamb birth weight, weaning weight or growth rate, regardless of zinc source,”  said Miss Cave. “And in the second experiment, hoof hardness at lambing was significantly greater in ewes receiving the Bioplex® zinc diet compared to those fed either the control or ZnO diets.”

Full details: Cave MK, Mackenzie Am, Wilkinson RG and Sinclair LA: “The effect of replacing traditional inorganic zinc supplements with organically chelated zinc supplements (Bioplex® Zn) on performance in sheep.”

Presented to the British Society of Animal Science Annual Conference, April 4 - 5, 2011, University of Nottingham, UK.

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Supplementing dairy cow diets with milled rapeseed resulted in a significant decrease in milk fat saturated fatty acid concentration, which was persistent for 70 days. An interesting finding for producers looking to produce ‘healthier’ milk for today’s discerning consumers.

The decrease was detected by scientists working in the UK and Finland. “Including oilseeds in the dairy cow diet is an effective strategy to reduce milk fat saturated fatty acid concentrations,” the University of Reading’s Kirsty Kliem told delegates at this year’s British Society of Animal Science’s annual conference, held at the University of Nottingham.

“But the rumen ecosystem requires time to adapt to dietary change. So we set out to assess the persistency of changes in milk fatty acid composition due to milled rapeseeds, over a 10-week period,” she added, explaining the rationale behind her team’s work.

The study took 30 cows, blocked according to milk yield one week before the start of the study and randomly allocated to one of two dietary treatments according to a repeated measures randomised block design. Treatments fed over 70 days were a control diet (CPO) containing 41g/kgDM calcium salts of palm oil distillate (Megalac) or the same basal diet with Megalac being replaced by 47g/kgDM lipid derived from rapeseed milled with wheat.

Diets were fed as a total mixed ration with a 50:50 forage:concentrate ratio with the forage proportion comprising 3:1 mixture of maize silage:grass silage. Daily dry matter intake and milk yield were recorded throughout the experiment. And milk samples collected on days 0, 28, 49 and 70 were submitted for fat, crude protein, lactose and fatty acid composition.

“And we found that there was no effect of treatment on dry matter intake or milk yield, but there was a reduction in total saturated fatty acid (SFA) content, mainly 16:0 concentration, in milk from the rapeseed-fed cows compared with the CPO diet, which persisted for the 70 day trial.

“The decrease can be attributed to both partial replacement of the control supplement, which has a high 16:0 content, with rapeseed lipids, but also inhibition of mammary de novo synthesis of 16:0 by long chain monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) from rapeseed,” said Ms Kliem.

The milled rapeseeds also increased milk total cis-MUFA and trans-MUFA content compared with the CPO diet, effects that were maintained until the end of the 70 day study.”

The total conjugated linoleic acid (CLA) concentration in milk fat was also greater following rapeseed supplementation compared with CPO. “And the increase persisted for 70 days, although the concentration of non-conjugated 18:2 isomers was lower in milk from cows supplemented with rapeseeds,” she added.

Full details: Kliem KE, Shingfield KJ, Jones AK and Givens DI: “Persistency of the effect of dietary milled rapeseeds on the milk fatty acid composition of lactating cows fed maize silage-based diets.”

Presented to the British Society of Animal Science Annual Conference, April 4 - 5, 2011, University of Nottingham, UK.

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Some good news for dairy producers, from Northern Ireland’s top dairy research facilities, that takes them a step closer to determining just how to get cows off to the very best start post calving – a critical time in the dairy production cycle.

The high milk production potential of the modern dairy cow frequently results in excessive and prolonged periods of negative energy balance (NEB) during early lactation. “And the most common approach to reduce NEB is to increase energy intake by increasing the proportion of concentrates being offered,” the Agri-Food and Biosciences Institute’s Ryan Law told delegates at this year’s British Society of Animal Science’s annual conference, held at the University of Nottingham.
 
“However, offering diets containing high levels of concentrates can lead to rumen acidosis, impaired rumen function and reduced intakes, the latter exacerbating NEB.
Introducing concentrates into the diet of fresh calved cows at a slower rate is likely to improve rumen function.”

He added that diet crude protein (CP) content is likely to be reduced through offering a lower concentrate diet in early lactation. “Offering a lower protein diet has been shown to reduce milk output, have no effect on dry matter intake, and to improve cow energy status. So the objective of our study was to compare two very different strategies for introducing concentrates into the diet in early lactation, namely a rapid build-up or a delayed build-up.”

The team took 60 autumn-calving Holstein Friesian cows and offered them a basal diet (via feeder wagon) containing 35% concentrate and 65% forage on a dry matter basis (150g CP/kgDM and 12MJ of ME/kgDM). Cows were allocated to one of two post-calving concentrate allocation strategies (via out-of-parlour feeders), namely a rapid build up of concentrates (RBU) or a delayed build up of concentrates (DBU).

With the rapid build-up treatment cows were offered 2kg concentrate/cow/day on the day of calving, and this was then built up incrementally (0.5kg/day) to a maximum of 7kg/cow/day at day 10 post calving. Cows allocated the delayed build-up treatment received no additional concentrate via out-of-parlour feeders until day 28 of lactation, and thereafter received incremental concentrate levels (0.5kg/day) to a maximum of 7kg/cow/day at day 42 post calving. Cows remained on these two dietary treatments until day 150 of lactation.

“Total dry matter intake was unaffected by concentrate build-up strategy, but forage intake was significantly higher for cows allocated to DBU treatment and concentrate intakes were lower,” said Dr Law.

“Neither milk yield nor milk composition was affected by concentrate build-up strategy and despite the lack of treatment effects on milk production, cows on DBU returned to positive energy balance earlier (week 7 post calving), compared to those on RBU (week 19 post-calving),” he added.

Full details: Law RA, McGettrick S, Ferris C: “Effect of concentrate build-up strategy in early lactation on production performance, health and fertility of high-yielding dairy cows.”

Presented to the British Society of Animal Science Annual Conference, April 4 - 5, 2011, University of Nottingham, UK.

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Trails in Northern Ireland have shown that concentrate allocation strategy had no effect on cow performance and that a simple ‘flat-rate’ concentrate feeding strategy is as effective as a more complex ‘feed-to-yield’ strategy.

“In order to meet the nutrient requirements of high yielding dairy cows while grazing, concentrate supplementation is normally considered essential,” the Agri-Food and Biosciences Institute’s Andrew Dale told delegates at this year’s British Society of Animal Science’s annual conference, held at the University of Nottingham.

“The efficient feeding of concentrates at farm level is made more difficult in herds with a spread calving pattern, and on many Northern Ireland dairy units cows now calve for at least nine months of the year. So most herds comprise cows in early, mid and late lactation.”
 
“But concentrate feed costs represent a significant proportion of variable costs on most dairy units and, as such, concentrates should be used efficiently,” he added, explaining the rationale behind his  team’s study, which set out to compare the effects of two allocation strategies, namely ‘flat rate’ and ‘feed-to-yield’, on the performance of 56 grazing Holstein Friesian dairy cows in a continuous design study.

Concentrate feed levels with the ‘flat-rate’ treatment were calculated based on the difference between the assumed milk yield potential of grazed grass as the sole feed (this was 25, 20, 20, 16 and 12kg/cow/day, for multiparous cows, and 20, 16, 16, 12.8 and 9.6kg/cow/day for primiparous cows, during May, June, July, August and September respectively) and the average yield of cows on that treatment, with concentrates offered at 0.6kg/litre milk to make up the difference.

The same total quantity of concentrates offered within the ‘flat rate’ treatment group was also offered within the ‘feed-to-yield’ treatment group.

 “And we found that concentrate allocation strategy had no effect on average milk yield, milk composition or milk-fat-plus-protein yield,” said Mr Dale.

End of study liveweight of the cows on the ‘flat rate’ treatment was not different from that of cows on the ‘feed-to-yield’ treatment.

“These results suggest that with moderate yielding cows in mid lactation, a simple flat rate concentrate feeding strategy is as effective as a more complex ‘feed-to-yield’ strategy,” added Mr Dale. “But, within this study, concentrates were fed to match the requirements of the ‘average’ animal within the ‘flat-rate’ treatment, thus concentrates were not being overfed, in contrast to practise on many farms.”

Full details: Dale AJ, Ferris CP and McGettrick S: “The response of grazing dairy cows to a ‘flat rate’ or a ‘feed to yield’ concentrate allocation strategy.”

Presented to the British Society of Animal Science Annual Conference, April 4 - 5, 2011, University of Nottingham, UK.

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Feeding milled rapeseed as a lipid and protein supplement for lactating dairy cows reduced methane production per day, per unit of dry matter intake and per unit of milk yield.

Some interesting results of a trial, carried out at the University of Reading, for environmentally conscious dairy producers.

The team of scientists, led by Les Crompton, found that every 1% of added lipid reduced methane emissions, relative to dry matter intake, by 2.5% and methane emission relative to milk yield by 7%.

“And feeding milled rapeseed decreased milk saturated fatty acids and increased cis-MUFA, while minimising milk trans-MUFA and could be used as part of an overall strategy to improve human health and food security,” Dr Crompton told delegates at this year’s British Society of Animal Science’s annual conference, held at the University of Nottingham.

With the aim of improving production efficiency, lipid has long been added to ruminant diets as an energy supplement, particularly for high yielding dairy cows in early or mid lactation. Manipulation of dietary fatty acid composition, with a view to altering milk fatty acid profile, has also received much interest. Most recently this has been in light of health issues arising from consumption of saturated fatty acids.

Current global efforts to reduce anthropogenic sources of greenhouse gas emissions has led to further interest in the effects of dietary lipids on methane emissions by ruminants. Previous work has also shown that feeding frequency can affect methane emission in dairy cows.

Dr Crompton’s team took four Holstein-Friesian dairy cows, in mid-lactation, which were randomly allocated to one of the four treatments. The control diet was formulated to provide a crude protein level of approximately 150 g/kg dry matter (DM) and was fed as a total mixed ration comprising a 50:50 mixture (on a DM basis) of forage:concentrate, while the forage consisted of a 75:25 blend (DM basis) of maize:grass silage.

The treatments consisted of the control diet fed twice daily (Con ×2), the control diet containing 35g/kgDM of lipid from milled rapeseed fed twice (Rape ×2) or once (Rape ×1) daily and the milled rapeseed diet with daily fluctuations in forage:concentrate ratio from 45:55 to 55:45 (while keeping the rapeseed at a constant proportion) fed once daily (Rape4/5 ×1).

Diets were formulated to be isoenergetic and isonitrogenous. Measurements of respiratory exchange, including methane production, in conjunction with total urine and faecal collection were obtained over four days during the final week of each period, when cows were housed in open-circuit respiration chambers. Milk fatty acid composition was measured and expressed as a weight percentage of total fatty acids.

“And we found that daily methane emission was reduced by all diets containing milled rapeseed compared to the control diet, with the largest decrease observed for the Rape ×1 treatment, which also tended to reduce dry matter intake,” said Dr  Crompton.

“The average reduction in methane emission for the three milled rapeseed diets was 15%. Methane emissions per unit of dry matter intake was also decreased by feeding rapeseed, however, the reduction was only significant for the diets that were fed once daily,” he added.

Methane emissions per unit of milk yield were also reduced by feeding rapeseed, with an average decrease of 20%. Feeding rapeseed reduced the concentration of total saturated fatty acids in milk fat by approximately 17%.

Full details: Crompton LA, Mills JAN, Kliem KE and Reynolds CK: “Effect of feeding milled rapeseed on methane emission and milk fatty acid composition in lactating dairy cows.”

Presented to the British Society of Animal Science Annual Conference, April 4 - 5, 2011, University of Nottingham, UK.

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