Net Energy For Lactation Research Articles

Forage legume species determine the nutritional quality of binary mixtures with perennial ryegrass in the first production year

There is increasing interest in forage legumes as ruminant feeds in Europe as alternatives to using mineral N fertilizer on temporary grassland. Successful management of grass–legume mixtures depends on the suitability of the forage legume species to the cutting frequency, and its nutritional quality for animals. An experiment was completed in 2004 and 2005 on two sites at the University of Kiel (Germany) to examine the response of legume-perennial ryegrass (Lolium perenne L.) mixtures to cutting frequency in terms of dry matter (DM) yield, N2 fixation, net energy for lactation (NEl), plant cell wall content, and crude protein (CP) content and CP fractions in the first production year. Different legumes in binary mixtures with perennial ryegrass (L. perenne L.), red clover (Trifolium pratense L.), white clover (Trifolium repens L.), hay-type and grazing-type alfalfa (Medicago sativa L.), birdsfoot trefoil (Lotus corniculatus L.), Caucasian clover (Trifolium ambiguum M. Bieb.) and two monocultures of perennial ryegrass (with and without cattle slurry supplying 20gN/m2) were examined under two cutting frequencies. All legume–grass mixtures outperformed perennial ryegrass with and without slurry in terms of DM yield, irrespective of cutting frequency. Production from both birdsfoot trefoil and Caucasian clover in grass–legume mixtures were very low, similar to unfertilized pure stands of grass, and the low production was consistent with slow and deficient establishment of birdsfoot trefoil and Caucasian clover, as observed by others. Nutritional quality of Caucasian clover was comparable to white clover. The companion grass benefited from the N transferred by forage legumes and their growth habit. This was especially evident for white clover, resulting in the highest companion grass yield and, in consequence, high mixture DM yield in both the 3 and 5 cut systems. Differences in agronomic performance of the legume–grass mixtures, and the grass monocultures, were related to the legume species in the mixture rather than cutting system. Forage legume species determined the nutritional quality and yield of binary mixtures with perennial ryegrass in the first production year.

Estimating fermentation characteristics and nutritive value of ensiled and dried pomegranate seeds for ruminants using in vitro gas production technique

The purpose of this study was to determine the chemical composition and estimation of fermentation characteristics and nutritive value of ensiled and dried pomegranate seeds using in vitro gas production technique. Samples were collected, mixed, processed (ensiled and dried) and incubated in vitro with rumen liquor taken from three fistulated Iranian native (Taleshi) steers at 2, 4, 6, 8, 12, 16, 24, 36, 48, 72 and 96 h. The results showed that ensiling lead to significant increase in gas production of pomegranate seeds at all incubation times. The gas volume at 24 h incubation, were 25.76 and 17.91 ml/200mg DM for ensiled and dried pomegranate seeds, respectively. The gas production rate (c) also was significantly higher for ensiled groups than dried (0.0930 vs. 0.0643 ml/h). The organic matter digestibility (OMD), metabolizable energy (ME), net energy for lactation (NEL) and short chain fatty acids (SCFA) of ensiled pomegranate seeds were significantly higher than that of dried samples (43.15%, 6.37 MJ/kg DM, 4.43 MJ/kg DM, 0.5553 mmol for ensiled samples vs. 34.62%, 5.10 MJ/kg DM, 3.56 MJ/kg DM, 0.3680 mmol for dried samples, respectively). It can be concluded that ensiling increases the nutritive value of pomegranate seeds.

Intake, nutrient digestibility and milk yield of dairy cows fed urea and two levels of crude protein in diets with sugar cane.

The objective of this study was to evaluate the effect of two Crude Protein (CP) levels and two nitrogen sources in the diets of dairy cows on DM and nutrient intake, total apparent digestibility, ruminal fermentation, milk yield and composition and energy balance using sugarcane as forage. Twelve multiparous Holstein cows, averaging 235 days of milking and 22.0 kg of milk day were distributed into three balanced and contemporary 4x4 Latin squares. The study consisted of four experimental periods of 21 days with 14 days for diet adaptation and the remainder for sampling. The cows were fed isocaloric diets with ad libitum intake and forage based on sugarcane in a 2x2 factorial arrangement of treatments: two main nitrogen sources (soybean meal andurea) and two levels of CP and 156 g CP kg-1 DM). Milk samples for compositional analysis were collected on the 14-17th days of each period. Ruminal fluid samples were collected by an esophageal tube, 3 h after morning feeding, for pH, short chain fatty acid and ammonia nitrogen analysis. Apparent digestibility was determined by means of an internal indicator (ADFi). No effect of diet was observed on Dry Matter Intake (DMI) (kg/day), net energy for lactation (Mcal/day) or total nutrientapparent digestibility. Interactions between nitrogen source and diet crude protein content were observed on rumen pH (p = 0.007) and acetate to propionate ratio (p = 0.003). A tendency was observed (p = 0.052) toward an effect of CP levels on milk protein yield (kg/day) as the cows fed diets with soybean meal produced more milk protein than those fed diets with urea. The results indicate that diets with lower levels of CP do not alter the milk yield and composition of dairy cows in the final third of lactation.

Ground wheat grain for midlactation cows: challenging a common wisdom.

The objective was to determine the effects of ground wheat grain (GW) inclusion rate, grinding extent (GE), and their interaction on lactating cow performance. Eight midlactation cows in 3 × 4 m individual boxes were used in a 4 × 4 replicated Latin square design study with 4 21 d periods. GW was fed at either 10% or 20% of diet dry matter (DM), as either finer or coarser particles. DM intake increased and net energy for lactation (NEL) intake tended to increase when GW was fed at 10% instead of 20% of diet DM. Milk energy yield, milk solids content and yield, and urine pH were unaffected. Fecal pH tended to increase at 20% versus 10% GW. Total tract apparent NDF, but not DM, digestibility tended to be greater for coarsely than finely GW and tended to be greater at 10% versus 20% GW. GW at 10% versus 20% of diet DM decreased blood BHBA and increased blood concentrations of total proteins and albumin. Data provide novel evidence that both finely and coarsely ground WG can be safely fed up to 20% midlactation cows. Commercial accessibility and cost will determine feeding preference of wheat grain to dairy cows.

Effects of forage type, forage to concentrate ratio, and crushed linseed supplementation on milk fatty acid profile in lactating dairy cows

The effects of an increasing proportion of crushed linseed (CL) in combination with varying forage type (grass or corn silage) and forage to concentrate ratio (F:C), and their interactions on milk fatty acid (FA) profile of high-producing dairy cows was studied using a 3-factor Box-Behnken design. Sixteen Holstein and 20 Swedish Red cows were blocked according to breed, parity, and milk yield, and randomly assigned to 4 groups. Groups were fed different treatment diets formulated from combinations of the 3 main factors each containing 3 levels. Forage type (fraction of total forage dry matter, DM) included 20, 50, and 80% grass silage, with the remainder being corn silage. The F:C (DM basis) were 35:65, 50:50, and 65:35, and CL was supplied at 1, 3, and 5% of diet DM. Starch and neutral detergent fiber content (DM basis) of the treatment diets ranged from 117 to 209g/kg and 311 to 388g/kg, respectively. Thirteen treatment diets were formulated according to the Box-Behnken design. During 4 experimental periods of 21 d each, all treatment diets were fed, including a repetition of the center point treatment (50% grass silage, 50:50F:C, 3% CL) during every period. Intake, production performance, and milk FA profile were measured, and response surface equations were derived for these variables. Shifting from 80% grass silage to 80% corn silage in the diet linearly increased dry matter intake (DMI), net energy for lactation (NEL) intake, cis-9,cis-12-C18:2 (C18:2n-6) intake, and milk yield, and linearly decreased cis-9,cis-12,cis-15-C18:3 (C18:3n-3) intake and milk fat content. Shifting from a high forage to a high concentrate diet linearly increased DMI, NEL intake, C18:2n-6 intake, and milk yield, and decreased milk fat content. Supplementation of CL linearly increased C18:3n-3 intake, but had no effect on DMI, NEL intake, milk yield, or milk fat content. Shifting from 80% grass silage to 80% corn silage linearly increased proportions of trans-10-C18:1 and C18:2n-6 in milk fat, whereas the proportions of trans-11,cis-15-C18:2 and C18:3n-3 linearly decreased. Significant interactions between CL supplementation and F:C were found for proportions of trans-10-C18:1, trans-15-C18:1, cis-15-C18:1, trans-11,cis-15-C18:2, and C18:3n-3 in milk fat, with the highest levels achieved when the diet contained 5% CL and a 35:65F:C ratio. The effect of supplementing CL on several milk FA proportions, including C18:2n-6 and C18:3n-3, depends significantly on the F:C ratio and forage type in the basal diet.

Mediterranean-Mountain Grasslands (Ćićarija, Croatia): the Nutritive Value of Functional Groups

The aim of this study was to research the chemical composition, in-vitro digestibility of the organic matter (IVOMD) and net energy for lactation (NEL) contained in the samples of botanical functional groups, located in the Mediterranean-mountain grasslands on the Ćićarija mountainous plateau in Croatia.

An in vitro nutritive evaluation of olive tree (Olea europaea) pruning residues as affected by cutting regimen

Nutritive values of the branches from Olea europaea trees cut at 25, 50, 75 or 100cm distance from the tip were evaluated by determination of the in vitro digestible organic matter (IVDOM), metabolizable energy (ME), net energy lactation (NEL), and presence nutritional and anti-nutritional components. The values of nutritive components, nitrogen forms, IVDOM, ME and NEL declined and concentrations of crude fiber and cell wall constituents increased with the increase in cutting length. Total phenols, hydrolysable tannins and condensed tannins amounted to 70, 17 and 0.6g/kg DM, respectively. The addition of polyethylene glycol (PEG, 6000) to the plant samples incubated with rumen fluid at a ratio of (2:1 PEG:substrate) increased the values of IVDOM, ME and NEL by 40g/kg DM, 0.59MJ/kg DM and 0.42MJ/kg DM, respectively. IVDOM, ME and NEL were negatively correlated with crude fiber and cell wall constituents but positively correlated with nitrogen forms and non-fiber carbohydrates. Olive pruning branches in diameter <3mm could be used as sources of feeds for small ruminants.

Rumen fermentation and production effects of Origanum vulgare L. leaves in lactating dairy cows

A lactating cow trial was conducted to study the effects of dietary addition of oregano leaf material (Origanum vulgare L.; OV; 0, control vs. 500g/d) on ruminal fermentation, methane production, total tract digestibility, manure gas emissions, N metabolism, organoleptic characteristics of milk, and dairy cow performance. Eight primiparous and multiparous Holstein cows (6 of which were ruminally cannulated) were used in a crossover design trial with two 21-d periods. Cows were fed once daily. The OV material was top-dressed and mixed with a portion of the total mixed ration. Cows averaged 80±12.5 d in milk at the beginning of the trial. Rumen pH, concentration of total and individual volatile fatty acids, microbial protein outflow, and microbial profiles were not affected by treatment. Ruminal ammonia-N concentration was increased by OV compared with the control (5.3 vs. 4.3mM). Rumen methane production, which was measured only within 8h after feeding, was decreased by OV. Intake of dry matter (average of 26.6±0.83kg/d) and apparent total tract digestibly of nutrients did not differ between treatments. Average milk yield, milk protein, lactose, and milk urea nitrogen concentrations were unaffected by treatment. Milk fat content was increased and 3.5% fat-corrected milk yield tended to be increased by OV, compared with the control (3.29 vs. 3.12% and 42.4 vs. 41.0kg/d, respectively). Fat-corrected (3.5%) milk feed efficiency and milk net energy for lactation (NEL) efficiency (milk NEL ÷ NEL intake) were increased by OV compared with the control (1.64 vs. 1.54kg/kg and 68.0 vs. 64.4%, respectively). Milk sensory parameters were not affected by treatment. Urinary and fecal N losses, and manure ammonia and methane emissions were unaffected by treatment. Under the current experimental conditions, supplementation of dairy cow diets with 500g/d of OV increased milk fat concentration, feed and milk NEL efficiencies, and tended to increase 3.5% fat-corrected milk yield. The sizable decrease in rumen methane production with the OV supplementation occurred within 8h after feeding and has to be interpreted with caution due to the large within- and between-animal variability in methane emission estimates. The OV was introduced into the rumen as a pulse dose at the time of feeding, thus most likely having larger effect on methane production during the period when methane data were collected. It is unlikely that methane production will be affected to the same extent throughout the entire feeding cycle.

Intake and digestibility of fatty acids in late-lactating dairy cows fed flaxseed hulls supplemented with monensin

Flaxseed hull, a co-product obtained from flax processing, is a rich source of n-3 fatty acids but there is little information on digestibility of its nutrients by dairy cows. Four rumen-cannulated multiparous Holstein cows averaging 665 ± 21 kg of body weight and 190 ± 5 d in milk at the beginning of the experiment were assigned to a 4 × 4 Latin square design with four 28-d experimental periods to determine the effects of feeding monensin and flaxseed hulls on total tract apparent digestibility of nutrients and fatty acids. The four treatments were: (1) diet CO: control with neither flaxseed hulls nor monensin added; (2) diet FH containing 19·8 g flaxseed hulls/100 g dry matter (DM); (3) diet MO with 16 mg monensin/kg DM; (4) diet HM containing 19·8 g flaxseed hulls/100 g DM and 16 mg monensin/kg DM. Diets provided similar amounts of protein and net energy of lactation. Digestibility of crude protein was higher for diets containing flaxseed hulls and for diets supplemented with monensin. Flaxseed hulls supplementation decreased digestibility of acid and neutral detergent fibre. Significantly higher digestibility of ether extract and individual fatty acids was observed for treatments with flaxseed hulls compared with treatments without flaxseed hulls. A combination of flaxseed hulls and monensin did not result in better fatty acid digestibility than when feeding only flaxseed hulls.

Energy status, measured by computer tomography (CT)-scanning, and milk quality of dairy goats fed rations with various energy concentrations

The milk produced by Norwegian goats varies in quality with regard to level of free fatty acids (FFA) and sensory quality. The aim of this study was to relate the milk quality to the changes in the energy status of dairy goats during early and mid lactation when fed rations with various energy concentrations. Twelve goats of the Norwegian Dairy Breed were from lactation weeks 3 to 18 fed grass silages prepared from the primary growth at a very early or normal stage of maturity (harvesting times (HT) 1 and 3, respectively), supplemented with a low (LC; 0.6kg daily) or normal (NC; 1.2kg daily) level of concentrate. Energy status was estimated by changes in body composition measured by computer tomography (CT), calculated energy balance and blood parameters.Calculated increase in adipose tissue mass of the goats was highest for HT 1. During the first 18weeks of lactation only the goats fed the lowest energy diet (HT 3 with LC) mobilized from the adipose tissue (in average 3.26kg). The other goats deposited body fat throughout this period, and had low (<0.3mmol/l) blood concentration of non-esterified fatty acids (NEFA). Calculated energy balance was positive throughout the indoor experiment for goats fed HT 1. Both net energy lactation (NEL) intake and milk yield increased with earlier stage of grass maturity and was positively correlated to daily gain in adipose tissue mass. Milk FFA tended to be higher (P=0.09) for goats offered HT 1 (1.48mEq/l) than HT 3 (0.99mEq/l), but was not significantly affected by concentrate level. A high milk FFA concentration was correlated to a high NEL intake. The level of milk FFA increased when the goats were let out on mountain pasture in lactation weeks 26–30. This study documents that it is possible to avoid fat mobilization in early lactation by feeding the goats high energy diets, based on high quality grass silage. However, a high plane of nutrition during early and mid lactation seemed to increase milk lipolysis. A high-energy diet offered indoors during the first 18weeks of lactation did neither improve milk quality during the same period nor in the following mountain pasture period.

Desempenho produtivo de vacas recebendo dietas com capim-elefante submetido a diferentes adubações e níveis de concentrado

Os objetivos deste trabalho foram determinar o consumo de matéria seca total (MSDT), a produção e composição do leite de vacas lactantes quando submetidas a dietas à base de capim-elefante adubado quimicamente (CEAQ) ou organicamente (CEAO) e a energia líquida para lactação (ELL) e os nutrientes digestíveis totais (NDT) do capim-elefante na dieta. O CEAQ ou CEAO foi misturado ao concentrado em níveis de 400, 500 e 600 g na base da matéria seca (MS). Os tratamentos foram dispostos em delineamento em quadrado latino 6 x 6, esquema fatorial de 2 x 3 (adubação x nível de concentrado). Os teores médios de MSDT e os de FDN, PB, Ca e P da dieta na MS diferiram (P &lt; 0,05) para os diferentes níveis de concentrado. O consumo da MSDT e dos nutrientes aumentou (P &lt; 0,05) com a elevação dos níveis de concentrado, exceto para FDN. O capim adubado organicamente diminuiu o consumo da MSDT e da FDN da dieta total. A digestão da MS, MO e PB da dieta total não sofreu influência dos níveis de concentrado e foi para o CEAO. Houve queda (P &lt; 0,05) na digestão da FDN da dieta com o aumento nos níveis de concentrado. A produção e composição do leite não variaram com os níveis de concentrado nem com as diferentes adubações. O valor energético (ELL e NDT) do capim-elefante decresceu (P &lt; 0,05) à medida que os níveis de concentrado aumentaram na dieta e não foi influenciado pelo sistema de adubação. A eficiência de síntese de proteína microbiana em relação à PB da dieta consumida foi melhor para o nível de 400 g de concentrado.

Estimation of the nutritive value of grape pomace for ruminant using gas production technique

The aim of this study was to determine the chemical composition and estimation of nutritive value of white grape pomace (WGP) using in vitro gas production technique. Fermentation of WGP samples were carried out with rumen fluids obtained from three mature cannulated steers. The samples were collected from a factory in Urmia, Iran. The amount of gas production for WGP at 2, 4, 6, 8, 12, 24, 48, 72 and 96 h were measured. The results showed that the crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and non-fibrous carbohydrate (NFC) contents were 17.27, 59.5, 52.5 and 13.5%, respectively. Gas production at 24 h and potential gas production (a + b) were 30.92 and 79.89 ml, respectively. The organic matter digestibility (OMD), metabolizable energy (ME) and short chain fatty acid (SCFA) contents were 50.50%, 7.4 MJ kg -1 DM and 0.69 mmol, respectively. The net energy for lactation (NEL) content was 3.31 MJ kg -1 DM. According to the results of this study, it seems that WGP could be used as a valuable food industrial by-product in ruminant nutrition. Key words : Nutritive value, gas production, grape pomace, short chain fatty acid, metabolizable energy.

Substitution rate and milk yield response to corn silage supplementation of late-lactation dairy cows grazing low-mass pastures at 2 daily allowances in autumn

Feed costs in dairy production systems may be decreased by extending the grazing season to periods such as autumn when grazing low-mass pastures is highly probable. The aim of this autumn study was to determine the effect of corn silage supplementation [0 vs. 8kg of dry matter (DM) of a mixture 7:1 of corn silage and soybean meal] on pasture intake (PI), milk production, and grazing behavior of dairy cows grazing low-mass ryegrass pastures at 2 daily pasture allowances (PA; low PA=18 vs. high PA=30kg of DM/cow above 2.5cm). Twelve multiparous Holstein cows were used in a 4 × 4 Latin square design with 14-d periods. Pre-grazing pasture mass and pre-grazing plate meter pasture height averaged 1.8 t of DM/ha (above 2.5cm) and 6.3cm, respectively. The quality of the offered pasture (above 2.5cm) was low because of dry conditions before and during the experiment (crude protein=11.5% of DM; net energy for lactation=5.15 MJ/kg of DM; organic matter digestibility=61.9%). The interaction between PA and supplementation level was significant for PI but not for milk production. Supplementation decreased PI from 11.6 to 7.6kg of DM/d at low PA and from 13.1 to 7.3kg of DM/d at high PA. The substitution rate was, therefore, lower at low than at high PA (0.51 vs. 0.75). Pasture intake increased with increasing PA in unsupplemented treatments, and was not affected by PA in supplemented treatments. Milk production averaged 13.5kg/d and was greater at high than at low PA (+1.4kg/d) and in supplemented than unsupplemented treatments (+5.2kg/d). Milk fat concentration averaged 4.39% and was similar between treatments. Milk protein concentration increased from 3.37 to 3.51% from unsupplemented to supplemented treatments, and did not vary according to PA. Grazing behavior parameters were only affected by supplementation. On average, daily grazing time decreased (539 vs. 436min) and daily ruminating time increased (388 vs. 486min) from 0 to 8kg of supplement DM. The PI rate was 6g of DM/min lower in supplemented than in unsupplemented treatments (17 vs. 23g of DM/min). The high milk yield response to supplementation may be related to a cumulative effect of the low-mass pasture (low PI) and the low quality of the pasture, which strongly limited energy supply in unsupplemented cows.

The effect of trophism level and exploitation intensity on the production characteristics of grassland community dominated by Festuca arundinacea Schreb.

In 2004&amp;ndash;2009, a small-plot trial was conducted on permanent grassland dominated by Festuca arundinacea Schreb. on the mesohygrophytic site in order to evaluate effects of four levels of nutrition: F&lt;sub&gt;1&lt;/sub&gt; = without NPK fertilization, F&lt;sub&gt;2 &lt;/sub&gt;= P&lt;sub&gt;30&lt;/sub&gt; + K&lt;sub&gt;60&lt;/sub&gt;, F&lt;sub&gt;3&lt;/sub&gt; = N90 + P&lt;sub&gt;30&lt;/sub&gt; + K&lt;sub&gt;60&lt;/sub&gt;, F&lt;sub&gt;4&lt;/sub&gt; = N&lt;sub&gt;180&lt;/sub&gt; + P&lt;sub&gt;30&lt;/sub&gt; + K&lt;sub&gt;60&lt;/sub&gt; kg/ha), four levels of cutting intensity (I&lt;sub&gt;1&lt;/sub&gt;-4, I&lt;sub&gt;2&lt;/sub&gt;-3, I&lt;sub&gt;3&lt;/sub&gt;-2, early, I&lt;sub&gt;4&lt;/sub&gt;-2, late cut) and their interactive influence, i.e. a total of 16 variants on the production of forage dry matter, production of crude protein (CD) and net energy of lactation (NEL) per hectare. The dominant influence of N-nutrition is documented by significant differences in forage dry matter (DM) production between the variants (with the exception of F&lt;sub&gt;1&lt;/sub&gt;/F&lt;sub&gt;2&lt;/sub&gt;) ranging from 4.41&amp;ndash;4.80 to 8.44&amp;ndash;9.83 t/ha. The effect of different exploitation level on the production is subdominant and no significant differences were found either in the production of forage DM&lt;br /&gt;(I&lt;sub&gt;1&lt;/sub&gt;-6.41 &amp;ndash; I&lt;sub&gt;2&lt;/sub&gt;-6.59 &amp;ndash; I&lt;sub&gt;3&lt;/sub&gt;-6.97 &amp;ndash; I&lt;sub&gt;4&lt;/sub&gt;-7.50 t/ha) or in the production of nutrients. Management models to be recommended for the given type of sward with respect to the interactive influence, efficacy of forage production and quality are as follows: (a) three cuts/180 kg N + PK/ha with forage suitable for dairy cows; (b) two cuts/90 kg N + PK/ha with forage suitable for cattle breeds kept for meat.

Performance and metabolic profile of dairy cows during a lactational and deliberately induced negative energy balance with subsequent realimentation

Homeorhetic and homeostatic controls in dairy cows are essential for adapting to alterations in physiological and environmental conditions. To study the different mechanisms during adaptation processes, effects of a deliberately induced negative energy balance (NEB) by feed restriction near 100 d in milk (DIM) on performance and metabolic measures were compared with lactation energy deficiency after parturition. Fifty multiparous cows were studied in 3 periods (1=early lactation up to 12 wk postpartum; 2=feed restriction for 3 wk beginning at 98±7 DIM with a feed-restricted and control group; and 3=a subsequent realimentation period for the feed-restricted group for 8 wk). In period 1, despite NEB in early lactation [−42 MJ of net energy for lactation (NEL)/d, wk 1 to 3] up to wk 9, milk yield increased from 27.5±0.7kg to a maximum of 39.5±0.8kg (wk 6). For period 2, the NEB was induced by individual limitation of feed quantity and reduction of dietary energy density. Feed-restricted cows experienced a greater NEB (−63 MJ of NEL/d) than did cows in early lactation. Feed-restricted cows in period 2 showed only a small decline in milk yield of −3.1±1.1kg and milk protein content of −0.2±0.1% compared with control cows (30.5±1.1kg and 3.8±0.1%, respectively). In feed-restricted cows (period 2), plasma glucose was lower (−0.2±0.0 mmol/L) and nonesterified fatty acids higher (+0.1±0.1 mmol/L) compared with control cows. Compared with the NEB in period 1, the decreases in body weight due to the deliberately induced NEB (period 2) were greater (56±4 vs. 23±3kg), but decreases in body condition score (0.16±0.03 vs. 0.34±0.04) and muscle diameter (2.0±0.4 vs. 3.5±0.4mm) were lesser. The changes in metabolic measures in period 2 were marginal compared with the adjustments directly after parturition in period 1. Despite the greater induced energy deficiency at 100 DIM than the early lactation NEB, the metabolic load experienced by the dairy cows was not as high as that observed in early lactation. The different effects of energy deficiency at the 2 stages in lactation show that metabolic problems in early lactating dairy cows are not due only to the NEB, but mainly to the specific metabolic regulation during this period.

Prepartum nutrient intake alters palmitate metabolism by liver slices from peripartal dairy cows

We determined the effects of day relative to parturition and prepartum plane of nutrition on hepatic partitioning of palmitate metabolism to CO2, acid-soluble products (ASP), and esterified products (EP). Multiparous Holsteins (n=74) were fed different amounts of nutrients during the dry period in a 3 (far-off period diet) × 2 (close-up period diet) factorial arrangement. During the far-off period (d −60 to −25) cows received a low-energy control diet fed ad libitum (100NRC) to meet National Research Council (NRC) requirements, a moderate-energy diet fed ad libitum to exceed NRC recommendations for net energy of lactation (NEL) by >50% (150NRC), or the same diet fed at restricted intake to provide 80% of NEL requirements (80NRC). During the close-up period (d −24 until parturition), cows were fed a diet for ad libitum intake to meet NRC recommendations or in restricted amounts to provide 80% of calculated NEL requirements. After parturition, all cows had ad libitum access to a lactation diet. Liver slices from biopsies on d −30, −14, 1, 14, and 28 relative to parturition were used to determine conversion of [1-14C] palmitate to CO2, ASP, and EP. Across diets, oxidation of palmitate to CO2 was decreased postpartum, whereas oxidation to ASP was increased at d 1 postpartum compared with other times. Conversion of palmitate to EP increased markedly postpartum, with the greatest rates at d 1 postpartum. Conversion of palmitate to CO2 and ASP on d 1 postpartum was lower and the proportion of palmitate metabolism as EP was greater for cows fed 150NRC than for those fed 100NRC or 80NRC. Hepatic triacylglycerol concentration at d 1 postpartum was greatest for cows fed 150NRC. Palmitate metabolism did not differ between close-up diets. Hepatic triacylglycerol was negatively correlated with tissue metabolism of palmitate to CO2 and ASP but positively correlated with metabolism to EP. Hepatic triacylglycerol was highly correlated with NEFA concentrations on the day of calving and d 1 postpartum but not with NEFA prepartum. In contrast, plasma BHBA postpartum was not correlated with hepatic palmitate metabolism by liver slices but was highly correlated with NEFA concentration prepartum. Excessive energy intake during the far-off dry period decreased hepatic palmitate oxidation and shifted palmitate metabolism toward greater esterification, consistent with greater hepatic triacylglycerol accumulation postpartum.

Dry matter and nutritional losses during aerobic deterioration of corn and sorghum silages as influenced by different lactic acid bacteria inocula

The economic damage that results from aerobic deterioration of silage is a significant problem for farm profitability and feed quality. This paper quantifies the dry matter (DM) and nutritional losses that occur during the exposure of corn and sorghum silages to air over 14 d and assesses the possibility of enhancing the aerobic stability of silages through inoculation with lactic acid bacteria (LAB). The trial was carried out in Northern Italy on corn (50% milk line) and grain sorghum (early dough stage) silages. The crops were ensiled in 30-L jars, without a LAB inoculant (C), with a Lactobacillus plantarum inoculum (LP), and with a Lactobacillus buchneri inoculum (LB; theoretical rate of 1 × 106 cfu/g of fresh forage). The pre-ensiled material, the silage at silo opening, and the aerobically exposed silage were analyzed for DM content, fermentative profiles, yeast and mold count, starch, crude protein, ash, fiber components, 24-h and 48-h DM digestibility and neutral detergent fiber (NDF) degradability. The yield and nutrient analysis data of the corn and sorghum silages were used as input for Milk2006 to estimate the total digestible nutrients, net energy of lactation, and milk production per Mg of DM. The DM fermentation and respiration losses were also calculated. The inocula influenced the in vitro NDF digestibility at 24h, the net energy for lactation (NEL), and the predicted milk yield per megagram of DM, whereas the length of time of air exposure influenced DM digestibility at 24 and 48h, the NEL, and the predicted milk yield per megagram of DM in the corn silages. The inocula only influenced the milk yield per megagram of DM and the air exposure affected the DM digestibility at 24h, the NEL, and the milk yield per megagram of DM in the sorghum silages. The milk yield, after 14 d of air exposure, decreased to 1,442, 1,418, and 1,277 kg/Mg of DM for C, LB, and LP corn silages, respectively, compared with an average value of 1,568kg of silage at opening. In the sorghum silages, the milk yield, after 14 d of air exposure, decreased to 1,226, 1,278, and 1,250 kg/Mg of DM for C, LB, and LP, respectively. When the estimated milk yield per megagram of harvested DM of corn and sorghum silage were related to mold count, it was shown that the loss of potential milk production occurred when the mold count exceeded 4 log cfu/g of silage, and it was almost halved when the mold count reached values greater than 8 log cfu/g of silage. Inoculation with L. buchneri, at a rate of 1 × 106 cfu/g of fresh forage, enhanced the stability of the silage after exposure to air, and, consequently, contributed to maintaining the nutritional value of the harvested forage over time, for air exposure up to 7 d.

Prepartum dietary energy intake affects metabolism and health during the periparturient period in primiparous and multiparous Holstein cows

An experiment was conducted to determine the effect of prepartum plane of energy intake on metabolic profiles related to lipid metabolism and health in blood and liver. Primiparous (n=24) and multiparous (n=23) Holsteins were randomly assigned by expected date of parturition to 1 of 3 prepartum energy intakes. A high energy diet [1.62 Mcal of net energy for lactation (NEL)/kg; 15% crude protein] was fed for either ad libitum intake or restricted intake to supply 150% (OVR) or 80% (RES) of energy requirements for dry cows in late gestation. To limit energy intake to 100% of National Research Council requirements at ad libitum intake, chopped wheat straw was included as 31.8% of dry matter for a control diet (CON; 1.21 Mcal of NEL/kg of dry matter; 14.2% crude protein). Regardless of parity group, OVR cows had greater concentrations of glucose, insulin, and leptin in blood prepartum compared with either CON or RES cows; however, dietary effects did not carry over to the postpartum period. Prepartum nonesterified fatty acids (NEFA) were lower in OVR cows compared with either CON or RES cows. Postpartum, however, OVR cows had evidence of greater mobilization of triacylglycerol (TAG) from adipose tissue as NEFA were higher than in CON or RES cows, especially within the first 10 d postpartum. Prepartum β-hydroxybutyrate (BHBA) was not affected by diet before parturition; however, within the first 10 d postpartum, OVR cows had greater BHBA than CON or RES cows. Prepartum diet did not affect liver composition prepartum; however, OVR cows had greater total lipid and TAG concentrations and lower glycogen postpartum than CON or RES cows. Frequency of ketosis and displaced abomasum was greater for OVR cows compared with CON or RES cows postpartum. Controlling or restricting prepartum energy intake yielded metabolic results that were strikingly similar both prepartum and postpartum, independent of parity group. The use of a bulky diet controlled prepartum energy intake in multiparous and primiparous cows, improved metabolic status postpartum, and reduced the incidence of health problems. When metabolic profiles are considered collectively, cows overfed energy prepartum exhibited an “overnutrition syndrome” with characteristics of clinical symptoms displayed by diabetic or obese nonruminant subjects. This syndrome likely contributed to metabolic dysfunction postpartum.

NUTRITIVE VALUE OF GREEN MASS AND HAY FROM THE DIVČIBARE REGION

With the aim of forming a complete observation of the botanical composition and nutritive value of pasture and meadow hay from the Divcibare region, which is a typically hilly-mountain area in Serbia, investigations were designed to evaluate the quality of pasture and hay (chemical composition and energy value), as well as the losses which are results of drying pasture. Twelve samples of grass were taken from three different altitudes and after mowing, samples of hay were also taken from the same meadow. In a conventional chemical analysis (Weende) the chemical composition of grass and hay were determined. On the basic of this analysis nutritive values were calculated. Pasture and hay from the Divcibare region have a satisfying chemical composition, they can be used as a forage base and a source of nutrients for ruminants, predominantly, lowproducing livestock. The difference in content of proteins among samples from some localities might be bound with the content of fabaceae. The increase fibre content with the proportional decrease content of protein had a negative influence on the nutritive value in the samples of grass and hay. The Net Energy Lactation (NEL) of hay from the investigated region is near the lower limit reported as average for pasture and meadow hay. Significant higher nutritive values of green mass, calculated on dry matter (NEL 8.35 MJ/kg, SV 0.78 SJ/kg) when compared to the nutritive value of hay (NEL 8.12 MJ/kg, SV 0.74 SJ/kg) show that losses are results of haymaking. Nutrients losses during drying are in correlation with losses of proteins, lipids and mineral matter, but there is an increase in fiber. The change in chemical composition due to the described losses during drying and the negative influence on organic matter digestibility, led to a reduction in the energy value of the investigated samples.

Statistical evaluation of some environmental factors affecting the gross efficiency of crude protein in high producing dairy

Some environmental factors affecting the gross efficiency of crude protein (GECP) were studied using 2824 records of 501 lactating Holstein cows. The effects of some independent variables on the GECP were tested using a general linear model analysis. The GECP was significantly affected by parity and pregnancy stage and linearly related to dry matter intake, milk yield, milk fat, protein and lactose percentages, protein and lactose yields, dietary levels of net energy for lactation (NEL), crude protein (CP), ruminally undegradable protein (RUP), and ether extract (EE). Quadratic relation to the GECP with dietary levels of NEL, CP, RUP, and EE were also significant. This study showed that high producing animals, especially high protein yielding cows are more efficient users of dietary CP. Dietary requirements of NEL, RUP, and EE to maximize the GECP were estimated as 1.61 Mcal/kg, 7.14%, and 5.42%, respectively. In comparison to NRC estimations, it seems that more NEL, less CP, and more RUP are needed to maximize the protein efficiency of lactating dairy cows.