Effects of Physically Effective Neutral Detergent Fiber Content on Intake, Digestibility, and Chewing Activity in Fattening Heifer Fed Total Mixed Ration

Abstract

The objective of this study was to determine the effects of physically effective neutral detergent fiber (peNDF) content in total mixed ration (TMR) on dry matter intake, digestibility, and chewing activity in fattening Hanwoo (Bos taurus coreanae) heifers. The experiment was designed as a replicated 3×3 Latin square using 12 heifers. Fattening heifers were offered one of three diets [high (T1), medium (T2), and low (T3) peNDF] obtained by different mixing times (3, 10, and 25 min) for the same TMR feed. The peNDF content of TMR was determined by multiplying the proportion of dry matter retained by a 1.18 mm-screen in a Penn State Particle Separator by the dietary NDF content. The peNDF1.18 content was 30.36%, 29.20%, and 27.50% for the T1, T2, and T3 diets, respectively (p<0.05). Dry matter intake was not affected by peNDF content in TMR. Total weight gain in T1 group was significantly higher (p<0.05) than in T2 and T3 groups. However, weight gain did not differ between T2 and T3 groups. The feed conversion ratio decreased with an increase in the peNDF content (T1: 12.18, T2: 14.17, and T3: 14.01 g/g). An increase in the peNDF content of TMR was associated with a linear increase in the digestibility of dry matter, crude protein, crude fiber, neutral detergent fiber, and acid detergent fiber (p<0.05). Also, an increase in peNDF content of the TMR resulted in a linear increase in the number of chews in eating and ruminating (p<0.05), and consequently in the number of total chews (p<0.05). These results indicate that peNDF content affects digestibility and chewing activity. Consequently, the peNDF content of TMR should be considered for improving feed efficiency, digestibility, body weight gain, and performance in fattening heifers.

Toplam Karma Yemle Beslenen Besi Sığırlarında Fiziksel Etkin Nötral Deterjan Lifin Büyüme Performansına ve Sindirilebilirlik Üzerine Etkisi

“…Feed intake may be reduced due to a long particle size that occupies larger volumes per unit of DM weight in the rumen content. In contrast to the other studies [7] , DMI was increased linearly by increasing mixing time. According to the results of this study, the daily weight gain of the T2 diets was significantly (P<0.05) lower than those in the other groups, which was in accordance with another study by Jang et al [22] Feed conversion ratio (T1: 5.80; T2: 4.76 kg/kg) was decreased linearly by decreased peNDF ≥4mm (T1: 29.47; T2: 25.63).…”

“…Excessive amount of long fibres could limit dry matter intake and digestibility, as a short particle size decreases chewing activity and results in a decline of saliva production and rumen pH [18] . Especially regarding this concern, several studies have been conducted on dairy cows [8,19,20] , beef cattle [7,21] and goats [22] .…”

“…The greater the amount of saliva they produce, the more their buffering capacity becomes [6] . It is possible to measure feed particle size that uses peNDF ≥4mm and NDF content value of feeds [7] . peNDF ≥4mm is the product of NDF concentration to the physical effectiveness factor (pef ).…”

“…At 0 NDF, there is failure to stimulate chewing, and there is the maximum stimulation when Pef is 1 [8] . The Penn State particle Separator (PSPS) is being used at farms to determine the particle size and total mixed particles [7] . The model of PSPS consists of four screens with circular holes.…”

“…Poppi et al [9] reported that feed particles retained on a 1.18-mm sieve had high resistance to passage from the rumen resulting in increasing chewing and rumination activity. Reduction of particle size increases the release rate from the rumen, and digestibility is reduced [7] . If the consistency of the ruminal mat is better, the passage of feed particles to the omasum is lower [8] .…”