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Titolo:
FEEDING CORN AND BARLEY CONCENTRATES TO GRAZING DAIRY-COWS - MILK-PRODUCTION, PLASMA METABOLITE, RESPONSES TO INSULIN AND GLUCOSE CHALLENGES TO BETA-ADRENERGIC STIMULI
Autore:
GAGLIOSTRO GA; LAVANDERA SE;
Indirizzi:
INTA EEA BALCARCE,AREA PROD ANIM,CC 276 RA-7620 BALCARCE ARGENTINA CONSEJO NACL INVEST CIENT & TECN RA-7620 BALCARCE ARGENTINA
Titolo Testata:
Annales de zootechnie
fascicolo: 2, volume: 46, anno: 1997,
pagine: 147 - 161
SICI:
0003-424X(1997)46:2<147:FCABCT>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
AMMONIA TOXICITY; LACTATING COWS; CRUDE PROTEIN; CARBOHYDRATE; STARCH; DIETS; SHEEP; PREGNANCY; STEERS; LIVER;
Keywords:
MILK YIELD; CORN; BARLEY; PLASMA METABOLITES; GLUCOSE CHALLENGE; BETA-ADRENERGIC RESPONSES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
40
Recensione:
Indirizzi per estratti:
Citazione:
G.A. Gagliostro e S.E. Lavandera, "FEEDING CORN AND BARLEY CONCENTRATES TO GRAZING DAIRY-COWS - MILK-PRODUCTION, PLASMA METABOLITE, RESPONSES TO INSULIN AND GLUCOSE CHALLENGES TO BETA-ADRENERGIC STIMULI", Annales de zootechnie, 46(2), 1997, pp. 147-161

Abstract

Pastures with high degradable protein content may induce insulin resistance, reduced insulin release and high responses to beta-adrenergic signals. Twenty-seven multiparous lactating Holstein cows (85 +/- 17 days postpartum) grazing oat (Avena sativa) sward and rye grass (Loliumperenne) pasture were fed pasture alone (PA) or pasture supplemented with corn (GO) or barley (BA) based concentrates. The experiment was conducted at the Agricultural Research Station of Balcarce (INTA), Argentina (37 degrees 45'S, 58 degrees 18'W). The experimental period lasted 36 days, from 2 July to 6 August. On a dry matter (DM) basis, concentrates contained CO (75%) or BA (80%), soybean meal (19.6% for CO and5.6% for BA), sunflower meal (2.8% for CO and 11.8% for BA) and a vitamin-mineral complex (2.6%). Cows consumed concentrates at a rate of 6.33 and 5.31 kg cow(-1) day(-1) for CO and BA respectively. Total herbage allowance ranged from 21.07 to 29.82 kg DM cow(-1). Total pasture DM intake was higher (P < 0.05) in the PA treatment (11.93 kg cow(-1) day(-1)) than that of cows fed either the CO (11.02 kg cow(-1) day(-1)) or the BA (10.75 kg cow(-1) day(-1)) based concentrates. The milk production of cows was lower in the PA treatment (17.0 kg cow(-1) day(-1)) compared to CO (21.5 kg cow(-1) day(-1)) but not to BA (18.4 kg cow(-1) day(-1)) based concentrates (P < 0.05). Milk yield from cows receiving the CO or the BA based concentrates did not differ (P < 0.05). The fat content of milk from cows receiving the BA concentrate (28.4 g kg(-1)) was lower than that of unsupplemented cows (PA = 34.5 g kg(-1)) (P < 0.05) but not from cows receiving the CO based concentrate (30.1 g kg(-1)). Milk fat content did not differ between cows fed the CO compared to unsupplemented PA cows (P > 0.05). Milk protein or lactose content did not differ significantly between treatment groups. Milk protein yield was higher in the CO (P < 0.05) treatment. Live weight gain was higher in CO concentrate (0.532 kg cow(-1) day(-1)) compared to PA (-0.035 kg cow(-1) day(-1)) and similar between PA and BA (0.381 kgcow(-1) day(-1)) or the two concentrates (P < 0.05). Plasma levels ofglucose (G), triglyceride (TG) and non-esterified fatty acids (NEFA) were not affected by treatments (P > 0.05). Uraemia was lower in BA (21.2 mg dL(-1)) compared to PA (24.2 mg dL(-1)) but not to CO (22.3 mg dL(-1)) treatment (P < 0.05). Plasma levels of insulin (INS) were higher in the BA (8.89 mu U mL(-1) compared to PA (6.19 mu U mL(-1)) and CO (6.63 mu U mL(-1)) treatments (P < 0.05). Plasma INS was negatively correlated to milk yield (-0.354, P < 0.01) and to milk fat content (-0.374, P < 0.01). Plasma G responses to INS challenge were not affected by treatments (P < 0.52). Plasma NEFA concentrations 30 min after INS challenge were lower than the pre-injection levels (P < 0.05) but were not affected by treatments (P > 0.05). The antilipolytic effect of INS was no longer observed 60 min after the injection (P > 0.05) and NEFA concentrations 90 min after INS challenge resulted in higher than basal levels (P < 0.05). G concentrations 5, 10 and 15 min after glucose challenge were higher than pre-injection levels (P < 0.05) but similar between treatments. Calculated G concentration immediately after injection (131.9, 130.7 and 141.9 mg dL(-1)), G distribution volume (40.2, 41.6 and 40.3 L) and;hr fractional rate of G clearance (k) (-0.041: -0.045 and -0. 059) did not differ between PA, CO and BA treatments,respectively (P > 0.05). Decreases in NEFA after G challenge (P < 0.60) and plasma INS responses to G challenge (P > 0.05) did not differ between treatments. The surface under the INS curve tended to be lower (P < 0.09) with CO (304 mu U min(-1)) compared to PA (417 mu U min(-1)) and BA (469 mu U min(-1)). The fractional rate of INS clearance tended to be lower in PA (-0.02794) compared to CO (-0.04566) and BA (-0.05848) treatments. Higher beta-adrenergic responses, resistance to INS action, alterations in G metabolism or in the INS secretory response to G did not differ between unsupplemented cows exposed to higher ammonia absorption and cows receiving concentrates with different lumen starch degradability.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/09/20 alle ore 12:41:08