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Post-harvest management of sweet potatoes (SP) crop residues preserves nutrients, deactivates inhibitor compounds and improves rumen degradation. The aim of the study was to determine effects of drying crop residues and heating roots on forage value of a bio-fortified orange fleshed sweet potato (OFSP) variety in South Africa. The crop was harvested at maturity and roots separated from crop residues. Roots were washed, sliced and divided into three portions as SP roots that were frozen at -4°C for 4 weeks, SP 70

Abstract.A study was conducted to (i) determine in vitro ruminal dry matter (DM) fermentation kinetics, effective rumen degradation of DM (ED DM ), (ii) estimate energy fractions supply of lucerne leaf-meal (LLM) and composite diets of LLM with commercial pelleted calf meal and also (iii) determine the effects of substituting commercial pelleted calf meal with LLM on the intake, % ruminal nitrogen balance (RNB) and growth of the neonates (21-42 days old) and transition (43-56 days old) Holstein heifer calves. Forty-eight Holstein heifer calves were randomly assigned to three different dietary treatments in a complete randomised design of: (a) pelleted concentrate (PEL), (b) 65% pelleted concentrate: 35% LLM (P 65 L35 ); (c) and 50% pelleted concentrate: 50% LLM (P 50 L50 ). The study comprised of two experiments: neonatal (Experiment 1) and transition (Experiment 2) phases. Lucerne leaf-meal had gross energy of 16.2 MJ/kg and 25% crude protein DM. PEL diet was high in starch and bound protein compared with other diets. Inclusion of LLM in diets increased calcium levels but tended to decrease phosphorus levels. Calves were weaned at the age of 56 days. The feeds were incubated for 0, 4, 10, 18, 24 and 48 h using a Daisy II incubator. Rumen fluid was obtained from calves <50 days old. Large Ruminant Nutrition System was used to predict %RNB and energy density of the diets during neonatal and transition phases. Higher mean ED DM levels were found with LLM inclusions whereas fractions a, a + b and c did not vary. Neonates on diet C had higher (P < 0.05) daily DM and crude protein intakes, %RNB, total digestible nutrients, net energy at maintenance and net energy at gain during neonatal phase. Performance of calves was similar during the transition phase. LLM should be considered as a concentrate replacement in diets of neonates and calves.

Greenhouse gas emissions, such as enteric methane (CH4) from ruminant livestock, have been linked to global warming. Thus, easily applicable CH4 management strategies, including the inclusion of dietary additives, should be in place. The objectives of the current study were to: (i) compile a database of animal records that supplemented monensin and investigate the effect of monensin on CH4 emissions; (ii) identify the principal dietary, animal, and lactation performance input variables that predict enteric CH4 production (g/d) and yield (g/kg of dry matter intake DMI); (iii) develop empirical models that predict CH4 production and yield in dairy cattle; and (iv) evaluate the newly developed models and published models in the literature. A significant reduction in CH4 production and yield of 5.4% and 4.0%, respectively, was found with a monensin supplementation of ≤24 mg/kg DM. However, no robust models were developed from the monensin database because of inadequate observations under the current paper’s inclusion/exclusion criteria. Thus, further long-term in vivo studies of monensin supplementation at ≤24 mg/kg DMI in dairy cattle on CH4 emissions specifically beyond 21 days of feeding are reported to ensure the monensin effects on the enteric CH4 are needed. In order to explore CH4 predictions independent of monensin, additional studies were added to the database. Subsequently, dairy cattle CH4 production prediction models were developed using a database generated from 18 in vivo studies, which included 61 treatment means from the combined data of lactating and non-lactating cows (COM) with a subset of 48 treatment means for lactating cows (LAC database). A leave-one-out cross-validation of the derived models showed that a DMI-only predictor model had a similar root mean square prediction error as a percentage of the mean observed value (RMSPE, %) on the COM and LAC database of 14.7 and 14.1%, respectively, and it was the key predictor of CH4 production. All databases observed an improvement in prediction abilities in CH4 production with DMI in the models along with dietary forage proportion inclusion and the quadratic term of dietary forage proportion. For the COM database, the CH4 yield was best predicted by the dietary forage proportion only, while the LAC database was for dietary forage proportion, milk fat, and protein yields. The best newly developed models showed improved predictions of CH4 emission compared to other published equations. Our results indicate that the inclusion of dietary composition along with DMI can provide an improved CH4 production prediction in dairy cattle.

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