Feed intake, ruminal fermentation, and animal behavior of beef heifers fed forage free diets containing nonforage fiber sources.

Eight Simmental heifers (initial BW 313.4 ± 13.2 kg) were randomly assigned to 1 of 4 experimental treatments in a 4 × 4 double Latin square design. The experiment was performed in four 28-d periods. Treatments tested were a control diet in which barley straw (BS) was used as a fiber source and 3 diets where the main difference was the nonforage fiber source used: soybean hulls (SH), beet pulp (BP) in pellets, and whole cottonseed (WCS). All ingredients, except the fiber sources, were ground through a 3-mm screen. Fiber ingredients were incorporated at 10, 17, 17, and 16% (on DM basis) in BS, SH, BP, and WCS, respectively. All diets were offered ad libitum as total mixed ration and designed to be isoenergetic (2.95 Mcal ME/kg DM), isonitrogenous (15% CP, DM basis), and with a NDF content of 20% (on DM basis) although there was a discrepancy between the theoretical and the actual chemical composition of the diets. Particle size separation was performed using the 3-screen Penn State Particle Separator. Animals were allotted in 8 individual roofed concrete pens equipped with a feedbunk and water trough. Intake was recorded over 7 d in the last week of each experimental period. Behavior was recorded for 24-h on d 2 and d 6 of each experimental week using a digital video recording device. A digital color camera was set up in front of each pen. Data recorded, except behavioral activities, were statistically analyzed using the MIXED procedure of SAS. To test treatment effect for each behavioral activity, analysis was performed using the GLIMMIX procedure of SAS. Diets ranked from greater to lesser proportion of particles of less than 1.18 mm as follows: SH, BS, WCS, and BP. Dry matter intake of heifers fed WCS was greater than the remaining treatments (P = 0.049). The greatest average ruminal pH was registered in heifers fed BS (6.4) and BP (6.3) whereas the smallest was recorded in SH diet (5.9), with WCS (6.2) occupying an intermediate position (P = 0.006). Total chewing time was greater (P = 0.001) in BS and WCS than in SH and BP. In conclusion, the nonforage fiber sources tested in this experiment can be used in forage-free diets fed to beef heifers as total mixed ration (TMR) without negative consequences in DMI in SH and BP diets and with an increased DMI in WCS diet. The WCS diet promoted rumination and total chewing time to the same degree as BS, which demonstrates that it is equally effective as this forage fiber source.

Effect of feeding method on intake and behaviour of individually reared beef heifers fed a concentrate diet from 115 to 185 kg of body weight.

A total of eight Simmental heifers (114 ± 3.2 days old and weighing 118 ± 3.8 kg BW) were used to study the effects of feeding method on intake and animal behaviour in a crossover design experiment. Treatments consisted of feeding concentrate and chopped barley straw as (1) choice (CH; concentrate and straw in separate feedbunks) or (2) total mixed ration (TMR; concentrate and straw in one feedbunk). Feeds were offered on an ad libitum basis, but always maintaining a concentrate to straw ratio of 90 to 10. The experiment was performed in two 21-day periods, and sampling was carried out in the last week of each period. At the end of each period, treatment was changed for heifers; hence, the final number of animals per treatment was eight. Intake was recorded over 7 consecutive days. BW was recorded at the beginning and the end of the experiment and on day 21 of each experimental period. Barley straw was coarsely chopped with a chopping machine. Once chopped, all the straw was handled for particle size separation using the 2-screen Penn State Particle Separator and only material of more than 8 mm was used to feed the heifers. Animal behaviour was video-recorded for 24 h on day 2 and day 6 of each experimental period. Concentrate intake and total dry matter intake of heifers fed with the CH feeding method were higher (P < 0.01 and P < 0.05) than when fed with TMR (5.1 and 5.3 v. 4.7 and 5.0 kg dry matter (DM)/day, respectively). Conversely, barley straw was consumed in higher amounts in heifers fed with the TMR feeding method (0.3 v. 0.2 kg DM/day, respectively; P = 0.001). The total NDF intake was similar in both treatments. In contrast, NDF intake from barley straw and physically effective NDF intake were higher in heifers fed with the TMR feeding method than when fed with CH. Feeding method used to feed heifers did not affect the consumption of the different kinds of barley straw particles and eating and drinking behaviours but affected ruminating behaviour. Heifers fed TMR spent more time ruminating than heifers fed concentrate and barley straw separately (376 v. 287 min/day, respectively; P < 0.01). TMR as the feeding method in intensive beef production systems could be a good approach to promote roughage intake.