. 1999. The nutritive value of hemp meal for ruminants. Can. J. Anim. Sci. 79: 91-95. Hemp meal (HM) is derived from the processing of hemp (Cannabis Sativa L.) seeds. The objective of this study was to determine the nutritive value of HM for ruminants. Two ruminally fistulated cows were used in a randomized completeblock design to estimate in situ ruminal dry matter (DM) and crude protein (CP) degradability of HM relative to canola meal (CM), heated canola meal (HCM) and borage meal (BM) meal. Intestinal availability of rumen undegraded CP was estimated using a pepsin-pancreatin in vitro assay. Twenty growing lambs were utilized in a completely randomized design to determine total-tract nutrient digestibility coefficients of diets in which HM replaced CM at 0, 25, 50, 75 and 100% as a protein source. Results of the in situ study showed that the soluble-CP fraction of HM was similar to that of HCM and lower (P < 0.05) than those of CM and BM. Rate of degradation of the potentially degradable CP fraction and effective CP degradability of HM was higher (P < 0.05) than HCM and lower (P < 0.05) than CM and BM. Rumen undegraded CP and intestinal digestibility of RUP were highest (P < 0.05) for HM and HCM (average 782.5 and 644.5 g kg -1 of CP, respectively), intermediate for CM (473.9 and 342.9 g kg -1 of CP, respectively) and lowest for BM (401.5 and 242.3 g kg -1 of CP, respectively). However, total available CP was similar for the four protein sources (average 857.8 g kg -1 of CP). Feeding up to 200 g kg -1 HM did not affect voluntary intake or total-tract nutrient digestibility coefficients for sheep fed a barley-based diets. Hemp meal is an excellent source of RUP, with high post-ruminal availability, and may be used to replace CM with no detrimental effects on nutrient utilization by sheep. Nous avons cherché à établir la valeur nutritive pour les ruminants du tourteau de chanvre (TCh), qui est le résultat de la trituration des graines de cette plante, Cannabis sativa L. Deux vaches munies d'une fistule ruminale ont servi, selon un dispositif expérimental en blocs aléatoires complets, à évaluer la dégradabilité ruminale in situ de la matière sèche (m.s.) et des protéines brutes (PB) du tourteau de chanvre, en regard de celle du tourteau de canola ordinaire (TC) ou chauffé (à 125°C pendant 10 min) TCC ainsi que du tourteau de bourrache (TB). La disponibilité intestinale des PB non dégradées dans le rumen était dosée au moyen d'un test in vitro à la pepsine-pancréatine. Vingt agneaux en croissance étaient utilisés selon un dispositif expérimental complètement aléatoire, pour déterminer les coefficients de digestibilité des nutriments sur l'ensemble de l'appareil digestif des régimes alimentaires dans lesquels TCh remplaçait TM comme composant protéique dans les proportions de 0, 25, 50, 75 et 100 %. Les résultats de l'expérience in situ montrent que la fraction de PB soluble du TCh était semblable à celle du TCC et était inférieure à celle mesurée pour TC et pour TB. Le taux de dégradation de la fraction des PB é...

[279][280][281][282][283][284][285][286][287][288][289][290]. The objective of this study was to investigate the effects of forage variety and stage of maturity on chemical composition, protein and carbohydrate subfractions, in vitro rumen degradability and energy content under the climatic conditions of western Canada. Two varieties of alfalfa (Medicago sativa L. cvs. Pioneer and Beaver) and timothy (Phleum pratense L. cvs. Climax and Joliette), grown at three locations in Saskatchewan (Canada), were cut at three stages [1 = 1 wk before commercial cut (early bud for alfalfa; joint for timothy); 2 = at commercial cut (late bud for alfalfa; pre-bloom head for timothy); and 3 = one week after commercial cut (early bloom for alfalfa; full head for timothy)]. The results showed that: (1) the varieties had minimal effects on nutritional value; however, (2) stage of cutting had a large impact on chemical composition, protein and carbohydrate fractions, in vitro rumen degradability and energy value. As plant maturity advanced from stage 1 to 3, the following changes were noticed: (a) CP was decreased [alfalfa: 20.2 to 17.6; timothy: 11.1 to 7.9% dry matter (DM)]; fibre was affected very little in alfalfa but increased in timothy [acid detergent fibre (ADF): 38.0 to 40.7; neutral detergent fibre (NDF): 68.7 to 72.8% DM]; lignin and neutral detergent insoluble protein (NDIP) were not affected in either forage; acid detergent insoluble protein (ADIP) was increased in alfalfa (3.5 to 17.1% CP), but no effect was seen in timothy; (b) the rapidly degradable protein fraction (PA) was reduced in alfalfa (51.2 to 34.8% CP) but increased in timothy (9.2 to 27.5% CP); the rapidly degradable fraction (PB1) increased in alfalfa (0.0 to 25.2% CP), but decreased in timothy (31.6 to 16.7%); the intermediate degradable fraction (PB2) decreased in both forages (alfalfa: 14.1 to 5.2; timothy: 37.8 to 29.4% CP); the slowly degradable fraction (PB3) declined in alfalfa (33.1 to 17.7% CP), but was not affected in timothy (averaging 21.3% CP); the unavailable fraction (PC) associated with the cell wall increased in alfalfa (3.5 to 17.1% CP), but did not change in timothy (averaging 5.2% CP); (c) in vitro rumen degradabilities of DM (IVDMD) and NDF (IVNDFD) increased at stage 2 and then declined at stage 3. The highest IVDMD and IVNDFD after a 48-h incubation were at cutting stage 2 (50.5 and 37.3%; 42.8 and 37.3% for alfalfa and timothy, respectively); (d) the energy content behaved in a quadratic fashion; it increased initially and then decreased with the highest energy contents at stage 2 for both forages (TDN 1x , DE 1x , DE p , ME p , NE Lp : 63.8% DM, 2.92, 2.68, 2.26, 1.40 Mcal kg -1 DM for alfalfa; 45.3% DM, 2.03, 1.86, 1.43, 0.82 Mcal kg -1 DM for timothy, respectively). In general, the best cutting was found at stage 2, which was latebud for alfalfa varieties and pre-bloom head for timothy. , à trois stades (1 = une semaine avant la récolte commerciale (début du bourgeonnement pour la luzerne; début de la montaison pour la fléole);...

Allelic variation (C to T transition that results in an Arg25Cys) in the leptin gene has been associated with increased fat deposition in beef cattle. We report that this same genetic variant is also present in dairy breeds. Body fat reserves play an important role in sustaining high milk production in early lactation, when energy intake is limited. To test for an association between the leptin single nucleotide polymorphism and milk productivity, we genotyped 416 Holstein cows and compared lactation performance data using a mixed model. Animals homozygous for the T allele produced more milk (1.5 kg/d vs. CC animals) and had higher somatic cell count linear scores, without significantly affecting milk fat or protein percent over the entire lactation. The increase in milk yield is most prominent in the first 100 d of lactation (2.44 kg/d), declining to 1.74 kg/d between 101 and 200 d in lactation. The milk yield advantage, observed in cows homozygous for the T allele, could represent a major economic advantage to dairy producers.

Nine multiparous Holstein cows were used in three 3 × 3 Latin squares to investigate the effects of feeding unheated and micronised flaxseed on milk yield and milk fatty acid composition. Three diets were formulated to meet the nutrient requirement of dairy cows in early lactation: a control diet with no added flaxseed (NFS), an unheated flaxseed diet (UFS) and a micronised flaxseed diet (MFS). The level of flaxseed in UFS and MFS was 70 g kg −1 of the diet dry matter (DM). Feeding flaxseed to dairy cows had no effect on DM intake or milk yield. However, energy-corrected milk was higher (P < 0.05) for cows fed MFS than for those fed UFS or NFS. Supplemental flaxseed reduced (P < 0.05) the milk fat percentage without affecting the concentration of milk protein or milk lactose. However, the yield of milk components was not affected by feeding flaxseed. The concentrations of short-chain (C 4:0 to C 12:0 ) and medium-chain (C 14:0 to C 17:0 ) fatty acids were decreased (P < 0.05) while those of long-chain fatty acids (C 18:0 to C 18:3 ) were increased (P < 0.05) in the milk of cows fed UFS and MFS compared with cows fed NSF. Feeding flaxseed to dairy cows can alter the milk fatty acid composition, but only minor effects on milk fatty acid composition can be expected by feeding micronised versus unheated flaxseed.

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